RecyclerView apps added.

Change-Id: If081193ea949419364bdb2dad5b3375493c1592a

RecyclerViewClickHandler/README.md

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+TrackMySleepQuality with RecyclerView - Solution Code for 7.4
+=============================================================
+
+Solution code for Android Kotlin Fundamentals Codelab 7.4 Interacting with RecyclerView items
+
+Introduction
+------------
+
+TrackMySleepQuality is an app for recording sleep data for each night.
+You can record a start and stop time, assign a quality rating, and clear the database.
+
+Learn how to make items in the RecyclerView clickable.
+Implement a click listener and navigate on click in your Android Kotlin app.
+
+Pre-requisites
+--------------
+
+You should be familiar with:
+
+* Building a basic user interface (UI) using an activity, fragments, and views.
+* Navigating between fragments, and using safeArgs to pass data between fragments.
+* Using view models, view model factories, transformations, and LiveData and their observers.
+* Creating a Room database, creating a DAO, and defining entities.
+* Using coroutines for database tasks and other long-running tasks.
+* How to implement a basic RecyclerView with an Adapter, ViewHolder, and item layout.
+* How to implement data binding for RecyclerView.
+* How to create and use binding adapters to transform data.
+* How to use GridLayoutManager.
+
+
+Getting Started
+---------------
+
+1. Download and run the app.
+
+License
+-------
+
+Copyright 2019 Google, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you under the Apache License, Version 2.0 (the "License"); you may not
+use this file except in compliance with the License.  You may obtain a copy of
+the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+License for the specific language governing permissions and limitations under
+the License.
+

RecyclerViewClickHandler/app/.gitignore

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+/build

RecyclerViewClickHandler/app/build.gradle

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+apply plugin: 'kotlin-kapt'
+apply plugin: 'androidx.navigation.safeargs'
+
+android {
+    compileSdkVersion 28
+    defaultConfig {
+        applicationId "com.example.android.trackmysleepqualityrecyclerview"
+        minSdkVersion 19
+        targetSdkVersion 28
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        vectorDrawables.useSupportLibrary = true
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    // Enables data binding.
+    dataBinding {
+        enabled = true
+    }
+
+}
+
+dependencies {
+
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+
+    // Support libraries
+    implementation "androidx.appcompat:appcompat:1.0.0"
+    implementation "androidx.fragment:fragment:1.0.0"
+    implementation "androidx.constraintlayout:constraintlayout:2.0.0-alpha2"
+
+    // Android KTX
+    implementation 'androidx.core:core-ktx:1.0.1'
+
+    // Room and Lifecycle dependencies
+    implementation "androidx.room:room-runtime:$room_version"
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
+    kapt "androidx.room:room-compiler:$room_version"
+    implementation "androidx.lifecycle:lifecycle-extensions:2.0.0"
+
+    // Coroutines
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutine_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutine_version"
+
+    // Navigation
+    implementation "android.arch.navigation:navigation-fragment-ktx:$navigationVersion"
+    implementation "android.arch.navigation:navigation-ui-ktx:$navigationVersion"
+
+    // Testing
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
+}
+

RecyclerViewClickHandler/app/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

RecyclerViewClickHandler/app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.android.trackmysleepquality">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher_sleep_tracker"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_sleep_tracker_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <meta-data
+            android:name="preloaded_fonts"
+            android:resource="@array/preloaded_fonts" />
+    </application>
+
+</manifest>

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/MainActivity.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        setContentView(R.layout.activity_main)
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/Util.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality
+
+import android.annotation.SuppressLint
+import android.content.res.Resources
+import android.os.Build
+import android.text.Html
+import android.text.Spanned
+import android.view.View
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.trackmysleepquality.database.SleepNight
+import java.text.SimpleDateFormat
+import java.util.*
+import java.util.concurrent.TimeUnit
+
+/**
+ * These functions create a formatted string that can be set in a TextView.
+ */
+
+private val ONE_MINUTE_MILLIS = TimeUnit.MILLISECONDS.convert(1, TimeUnit.MINUTES)
+private val ONE_HOUR_MILLIS = TimeUnit.MILLISECONDS.convert(1, TimeUnit.HOURS)
+
+/**
+ * Convert a duration to a formatted string for display.
+ *
+ * Examples:
+ *
+ * 6 seconds on Wednesday
+ * 2 minutes on Monday
+ * 40 hours on Thursday
+ *
+ * @param startTimeMilli the start of the interval
+ * @param endTimeMilli the end of the interval
+ * @param res resources used to load formatted strings
+ */
+fun convertDurationToFormatted(startTimeMilli: Long, endTimeMilli: Long, res: Resources): String {
+    val durationMilli = endTimeMilli - startTimeMilli
+    val weekdayString = SimpleDateFormat("EEEE", Locale.getDefault()).format(startTimeMilli)
+    return when {
+        durationMilli < ONE_MINUTE_MILLIS -> {
+            val seconds = TimeUnit.SECONDS.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.seconds_length, seconds, weekdayString)
+        }
+        durationMilli < ONE_HOUR_MILLIS -> {
+            val minutes = TimeUnit.MINUTES.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.minutes_length, minutes, weekdayString)
+        }
+        else -> {
+            val hours = TimeUnit.HOURS.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.hours_length, hours, weekdayString)
+        }
+    }
+}
+
+/**
+ * Returns a string representing the numeric quality rating.
+ */
+fun convertNumericQualityToString(quality: Int, resources: Resources): String {
+    var qualityString = resources.getString(R.string.three_ok)
+    when (quality) {
+        -1 -> qualityString = "--"
+        0 -> qualityString = resources.getString(R.string.zero_very_bad)
+        1 -> qualityString = resources.getString(R.string.one_poor)
+        2 -> qualityString = resources.getString(R.string.two_soso)
+        4 -> qualityString = resources.getString(R.string.four_pretty_good)
+        5 -> qualityString = resources.getString(R.string.five_excellent)
+    }
+    return qualityString
+}
+
+
+/**
+ * Take the Long milliseconds returned by the system and stored in Room,
+ * and convert it to a nicely formatted string for display.
+ *
+ * EEEE - Display the long letter version of the weekday
+ * MMM - Display the letter abbreviation of the nmotny
+ * dd-yyyy - day in month and full year numerically
+ * HH:mm - Hours and minutes in 24hr format
+ */
+@SuppressLint("SimpleDateFormat")
+fun convertLongToDateString(systemTime: Long): String {
+    return SimpleDateFormat("EEEE MMM-dd-yyyy' Time: 'HH:mm")
+            .format(systemTime).toString()
+}
+
+/**
+ * Takes a list of SleepNights and converts and formats it into one string for display.
+ *
+ * For display in a TextView, we have to supply one string, and styles are per TextView, not
+ * applicable per word. So, we build a formatted string using HTML. This is handy, but we will
+ * learn a better way of displaying this data in a future lesson.
+ *
+ * @param   nights - List of all SleepNights in the database.
+ * @param   resources - Resources object for all the resources defined for our app.
+ *
+ * @return  Spanned - An interface for text that has formatting attached to it.
+ *           See: https://developer.android.com/reference/android/text/Spanned
+ */
+fun formatNights(nights: List<SleepNight>, resources: Resources): Spanned {
+    val sb = StringBuilder()
+    sb.apply {
+        append(resources.getString(R.string.title))
+        nights.forEach {
+            append("<br>")
+            append(resources.getString(R.string.start_time))
+            append("\t${convertLongToDateString(it.startTimeMilli)}<br>")
+            if (it.endTimeMilli != it.startTimeMilli) {
+                append(resources.getString(R.string.end_time))
+                append("\t${convertLongToDateString(it.endTimeMilli)}<br>")
+                append(resources.getString(R.string.quality))
+                append("\t${convertNumericQualityToString(it.sleepQuality, resources)}<br>")
+                append(resources.getString(R.string.hours_slept))
+                // Hours
+                append("\t ${it.endTimeMilli.minus(it.startTimeMilli) / 1000 / 60 / 60}:")
+                // Minutes
+                append("${it.endTimeMilli.minus(it.startTimeMilli) / 1000 / 60}:")
+                // Seconds
+                append("${it.endTimeMilli.minus(it.startTimeMilli) / 1000}<br><br>")
+            }
+        }
+    }
+    // fromHtml is deprecated for target API without a flag, but since our minSDK is 19, we
+    // can't use the newer version, which requires minSDK of 24
+    //https://developer.android.com/reference/android/text/Html#fromHtml(java.lang.String,%20int)
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+        return Html.fromHtml(sb.toString(), Html.FROM_HTML_MODE_LEGACY)
+    } else {
+        @Suppress("DEPRECATION")
+        return Html.fromHtml(sb.toString())
+    }
+}
+
+/**
+ * ViewHolder that holds a single [TextView].
+ *
+ * A ViewHolder holds a view for the [RecyclerView] as well as providing additional information
+ * to the RecyclerView such as where on the screen it was last drawn during scrolling.
+ */
+class TextItemViewHolder(val textView: TextView): RecyclerView.ViewHolder(textView)

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/database/SleepDatabase.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+
+/**
+ * A database that stores SleepNight information.
+ * And a global method to get access to the database.
+ *
+ * This pattern is pretty much the same for any database,
+ * so you can reuse it.
+ */
+@Database(entities = [SleepNight::class], version = 1, exportSchema = false)
+abstract class SleepDatabase : RoomDatabase() {
+
+    /**
+     * Connects the database to the DAO.
+     */
+    abstract val sleepDatabaseDao: SleepDatabaseDao
+
+    /**
+     * Define a companion object, this allows us to add functions on the SleepDatabase class.
+     *
+     * For example, clients can call `SleepDatabase.getInstance(context)` to instantiate
+     * a new SleepDatabase.
+     */
+    companion object {
+        /**
+         * INSTANCE will keep a reference to any database returned via getInstance.
+         *
+         * This will help us avoid repeatedly initializing the database, which is expensive.
+         *
+         *  The value of a volatile variable will never be cached, and all writes and
+         *  reads will be done to and from the main memory. It means that changes made by one
+         *  thread to shared data are visible to other threads.
+         */
+        @Volatile
+        private var INSTANCE: SleepDatabase? = null
+
+        /**
+         * Helper function to get the database.
+         *
+         * If a database has already been retrieved, the previous database will be returned.
+         * Otherwise, create a new database.
+         *
+         * This function is threadsafe, and callers should cache the result for multiple database
+         * calls to avoid overhead.
+         *
+         * This is an example of a simple Singleton pattern that takes another Singleton as an
+         * argument in Kotlin.
+         *
+         * To learn more about Singleton read the wikipedia article:
+         * https://en.wikipedia.org/wiki/Singleton_pattern
+         *
+         * @param context The application context Singleton, used to get access to the filesystem.
+         */
+        fun getInstance(context: Context): SleepDatabase {
+            // Multiple threads can ask for the database at the same time, ensure we only initialize
+            // it once by using synchronized. Only one thread may enter a synchronized block at a
+            // time.
+            synchronized(this) {
+
+                // Copy the current value of INSTANCE to a local variable so Kotlin can smart cast.
+                // Smart cast is only available to local variables.
+                var instance = INSTANCE
+
+                // If instance is `null` make a new database instance.
+                if (instance == null) {
+                    instance = Room.databaseBuilder(
+                            context.applicationContext,
+                            SleepDatabase::class.java,
+                            "sleep_history_database"
+                    )
+                            // Wipes and rebuilds instead of migrating if no Migration object.
+                            // Migration is not part of this lesson. You can learn more about
+                            // migration with Room in this blog post:
+                            // https://medium.com/androiddevelopers/understanding-migrations-with-room-f01e04b07929
+                            .fallbackToDestructiveMigration()
+                            .build()
+                    // Assign INSTANCE to the newly created database.
+                    INSTANCE = instance
+                }
+
+                // Return instance; smart cast to be non-null.
+                return instance
+            }
+        }
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/database/SleepDatabaseDao.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import androidx.lifecycle.LiveData
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Update
+
+
+/**
+ * Defines methods for using the SleepNight class with Room.
+ */
+@Dao
+interface SleepDatabaseDao {
+
+    @Insert
+    fun insert(night: SleepNight)
+
+    /**
+     * When updating a row with a value already set in a column,
+     * replaces the old value with the new one.
+     *
+     * @param night new value to write
+     */
+    @Update
+    fun update(night: SleepNight)
+
+    /**
+     * Selects and returns the row that matches the supplied start time, which is our key.
+     *
+     * @param key startTimeMilli to match
+     */
+    @Query("SELECT * from daily_sleep_quality_table WHERE nightId = :key")
+    fun get(key: Long): SleepNight
+
+    /**
+     * Deletes all values from the table.
+     *
+     * This does not delete the table, only its contents.
+     */
+    @Query("DELETE FROM daily_sleep_quality_table")
+    fun clear()
+
+    /**
+     * Selects and returns all rows in the table,
+     *
+     * sorted by start time in descending order.
+     */
+    @Query("SELECT * FROM daily_sleep_quality_table ORDER BY nightId DESC")
+    fun getAllNights(): LiveData<List<SleepNight>>
+
+    /**
+     * Selects and returns the latest night.
+     */
+    @Query("SELECT * FROM daily_sleep_quality_table ORDER BY nightId DESC LIMIT 1")
+    fun getTonight(): SleepNight?
+
+    /**
+     * Selects and returns the night with given nightId.
+     */
+    @Query("SELECT * from daily_sleep_quality_table WHERE nightId = :key")
+    fun getNightWithId(key: Long): LiveData<SleepNight>
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/database/SleepNight.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+/**
+ * Represents one night's sleep through start, end times, and the sleep quality.
+ */
+@Entity(tableName = "daily_sleep_quality_table")
+data class SleepNight(
+        @PrimaryKey(autoGenerate = true)
+        var nightId: Long = 0L,
+
+        @ColumnInfo(name = "start_time_milli")
+        val startTimeMilli: Long = System.currentTimeMillis(),
+
+        @ColumnInfo(name = "end_time_milli")
+        var endTimeMilli: Long = startTimeMilli,
+
+        @ColumnInfo(name = "quality_rating")
+        var sleepQuality: Int = -1)

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepdetail/SleepDetailFragment.kt

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+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepdetail
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
+import androidx.navigation.fragment.findNavController
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.database.SleepDatabase
+import com.example.android.trackmysleepquality.databinding.FragmentSleepDetailBinding
+
+
+/**
+ * A simple [Fragment] subclass.
+ * Activities that contain this fragment must implement the
+ * [SleepDetailFragment.OnFragmentInteractionListener] interface
+ * to handle interaction events.
+ * Use the [SleepDetailFragment.newInstance] factory method to
+ * create an instance of this fragment.
+ *
+ */
+class SleepDetailFragment : Fragment() {
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+
+        // Get a reference to the binding object and inflate the fragment views.
+        val binding: FragmentSleepDetailBinding = DataBindingUtil.inflate(
+                inflater, R.layout.fragment_sleep_detail, container, false)
+
+        val application = requireNotNull(this.activity).application
+        val arguments = SleepDetailFragmentArgs.fromBundle(arguments)
+
+        // Create an instance of the ViewModel Factory.
+        val dataSource = SleepDatabase.getInstance(application).sleepDatabaseDao
+        val viewModelFactory = SleepDetailViewModelFactory(arguments.sleepNightKey, dataSource)
+
+        // Get a reference to the ViewModel associated with this fragment.
+        val sleepDetailViewModel =
+                ViewModelProviders.of(
+                        this, viewModelFactory).get(SleepDetailViewModel::class.java)
+
+        // To use the View Model with data binding, you have to explicitly
+        // give the binding object a reference to it.
+        binding.sleepDetailViewModel = sleepDetailViewModel
+
+        binding.setLifecycleOwner(this)
+
+        // Add an Observer to the state variable for Navigating when a Quality icon is tapped.
+        sleepDetailViewModel.navigateToSleepTracker.observe(this, Observer {
+            if (it == true) { // Observed state is true.
+                this.findNavController().navigate(
+                        SleepDetailFragmentDirections.actionSleepDetailFragmentToSleepTrackerFragment())
+                // Reset state to make sure we only navigate once, even if the device
+                // has a configuration change.
+                sleepDetailViewModel.doneNavigating()
+            }
+        })
+
+        return binding.root
+    }
+
+
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepdetail/SleepDetailViewModel.kt

@@ -0,0 +1,97 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepdetail
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MediatorLiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+import com.example.android.trackmysleepquality.database.SleepNight
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * ViewModel for SleepQualityFragment.
+ *
+ * @param sleepNightKey The key of the current night we are working on.
+ */
+class SleepDetailViewModel(
+        private val sleepNightKey: Long = 0L,
+        dataSource: SleepDatabaseDao) : ViewModel() {
+
+    /**
+     * Hold a reference to SleepDatabase via its SleepDatabaseDao.
+     */
+    val database = dataSource
+
+    /** Coroutine setup variables */
+
+    /**
+     * viewModelJob allows us to cancel all coroutines started by this ViewModel.
+     */
+    private val viewModelJob = Job()
+
+    private val night: LiveData<SleepNight>
+
+    fun getNight() = night
+
+
+    init {
+        night=database.getNightWithId(sleepNightKey)
+    }
+
+    /**
+     * Variable that tells the fragment whether it should navigate to [SleepTrackerFragment].
+     *
+     * This is `private` because we don't want to expose the ability to set [MutableLiveData] to
+     * the [Fragment]
+     */
+    private val _navigateToSleepTracker = MutableLiveData<Boolean?>()
+
+    /**
+     * When true immediately navigate back to the [SleepTrackerFragment]
+     */
+    val navigateToSleepTracker: LiveData<Boolean?>
+        get() = _navigateToSleepTracker
+
+    /**
+     * Cancels all coroutines when the ViewModel is cleared, to cleanup any pending work.
+     *
+     * onCleared() gets called when the ViewModel is destroyed.
+     */
+    override fun onCleared() {
+        super.onCleared()
+        viewModelJob.cancel()
+    }
+
+
+    /**
+     * Call this immediately after navigating to [SleepTrackerFragment]
+     */
+    fun doneNavigating() {
+        _navigateToSleepTracker.value = null
+    }
+
+    fun onClose() {
+        _navigateToSleepTracker.value = true
+    }
+
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepdetail/SleepDetailViewModelFactory.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepdetail
+
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+
+/**
+ * This is pretty much boiler plate code for a ViewModel Factory.
+ *
+ * Provides the key for the night and the SleepDatabaseDao to the ViewModel.
+ */
+class SleepDetailViewModelFactory(
+        private val sleepNightKey: Long,
+        private val dataSource: SleepDatabaseDao) : ViewModelProvider.Factory {
+    @Suppress("unchecked_cast")
+    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+        if (modelClass.isAssignableFrom(SleepDetailViewModel::class.java)) {
+            return SleepDetailViewModel(sleepNightKey, dataSource) as T
+        }
+        throw IllegalArgumentException("Unknown ViewModel class")
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityFragment.kt

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
+import androidx.navigation.fragment.findNavController
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.database.SleepDatabase
+import com.example.android.trackmysleepquality.databinding.FragmentSleepQualityBinding
+
+/**
+ * Fragment that displays a list of clickable icons,
+ * each representing a sleep quality rating.
+ * Once the user taps an icon, the quality is set in the current sleepNight
+ * and the database is updated.
+ */
+class SleepQualityFragment : Fragment() {
+
+    /**
+     * Called when the Fragment is ready to display content to the screen.
+     *
+     * This function uses DataBindingUtil to inflate R.layout.fragment_sleep_quality.
+     *
+     * It is also responsible for passing the [SleepQualityViewModel] to the
+     * [FragmentSleepQualityBinding] generated by DataBinding. This will allow DataBinding
+     * to use the [LiveData] on our ViewModel.
+     */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+
+        // Get a reference to the binding object and inflate the fragment views.
+        val binding: FragmentSleepQualityBinding = DataBindingUtil.inflate(
+                inflater, R.layout.fragment_sleep_quality, container, false)
+
+        val application = requireNotNull(this.activity).application
+        val arguments = SleepQualityFragmentArgs.fromBundle(arguments)
+
+        // Create an instance of the ViewModel Factory.
+        val dataSource = SleepDatabase.getInstance(application).sleepDatabaseDao
+        val viewModelFactory = SleepQualityViewModelFactory(arguments.sleepNightKey, dataSource)
+
+        // Get a reference to the ViewModel associated with this fragment.
+        val sleepQualityViewModel =
+                ViewModelProviders.of(
+                        this, viewModelFactory).get(SleepQualityViewModel::class.java)
+
+        // To use the View Model with data binding, you have to explicitly
+        // give the binding object a reference to it.
+        binding.sleepQualityViewModel = sleepQualityViewModel
+
+        // Add an Observer to the state variable for Navigating when a Quality icon is tapped.
+        sleepQualityViewModel.navigateToSleepTracker.observe(this, Observer {
+            if (it == true) { // Observed state is true.
+                this.findNavController().navigate(
+                        SleepQualityFragmentDirections.actionSleepQualityFragmentToSleepTrackerFragment())
+                // Reset state to make sure we only navigate once, even if the device
+                // has a configuration change.
+                sleepQualityViewModel.doneNavigating()
+            }
+        })
+
+        return binding.root
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityViewModel.kt

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * ViewModel for SleepQualityFragment.
+ *
+ * @param sleepNightKey The key of the current night we are working on.
+ */
+class SleepQualityViewModel(
+        private val sleepNightKey: Long = 0L,
+        dataSource: SleepDatabaseDao) : ViewModel() {
+
+    /**
+     * Hold a reference to SleepDatabase via its SleepDatabaseDao.
+     */
+    val database = dataSource
+
+    /** Coroutine setup variables */
+
+    /**
+     * viewModelJob allows us to cancel all coroutines started by this ViewModel.
+     */
+    private val viewModelJob = Job()
+
+    /**
+     * A [CoroutineScope] keeps track of all coroutines started by this ViewModel.
+     *
+     * Because we pass it [viewModelJob], any coroutine started in this scope can be cancelled
+     * by calling `viewModelJob.cancel()`
+     *
+     * By default, all coroutines started in uiScope will launch in [Dispatchers.Main] which is
+     * the main thread on Android. This is a sensible default because most coroutines started by
+     * a [ViewModel] update the UI after performing some processing.
+     */
+    private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
+
+    /**
+     * Variable that tells the fragment whether it should navigate to [SleepTrackerFragment].
+     *
+     * This is `private` because we don't want to expose the ability to set [MutableLiveData] to
+     * the [Fragment]
+     */
+    private val _navigateToSleepTracker = MutableLiveData<Boolean?>()
+
+    /**
+     * When true immediately navigate back to the [SleepTrackerFragment]
+     */
+    val navigateToSleepTracker: LiveData<Boolean?>
+        get() = _navigateToSleepTracker
+
+    /**
+     * Cancels all coroutines when the ViewModel is cleared, to cleanup any pending work.
+     *
+     * onCleared() gets called when the ViewModel is destroyed.
+     */
+    override fun onCleared() {
+        super.onCleared()
+        viewModelJob.cancel()
+    }
+
+    /**
+     * Call this immediately after navigating to [SleepTrackerFragment]
+     */
+    fun doneNavigating() {
+        _navigateToSleepTracker.value = null
+    }
+
+    /**
+     * Sets the sleep quality and updates the database.
+     *
+     * Then navigates back to the SleepTrackerFragment.
+     */
+    fun onSetSleepQuality(quality: Int) {
+        uiScope.launch {
+            // IO is a thread pool for running operations that access the disk, such as
+            // our Room database.
+            withContext(Dispatchers.IO) {
+                val tonight = database.get(sleepNightKey)
+                tonight.sleepQuality = quality
+                database.update(tonight)
+            }
+
+            // Setting this state variable to true will alert the observer and trigger navigation.
+            _navigateToSleepTracker.value = true
+        }
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityViewModelFactory.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+
+/**
+ * This is pretty much boiler plate code for a ViewModel Factory.
+ *
+ * Provides the key for the night and the SleepDatabaseDao to the ViewModel.
+ */
+class SleepQualityViewModelFactory(
+        private val sleepNightKey: Long,
+        private val dataSource: SleepDatabaseDao) : ViewModelProvider.Factory {
+    @Suppress("unchecked_cast")
+    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+        if (modelClass.isAssignableFrom(SleepQualityViewModel::class.java)) {
+            return SleepQualityViewModel(sleepNightKey, dataSource) as T
+        }
+        throw IllegalArgumentException("Unknown ViewModel class")
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/BindingUtils.kt

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.widget.ImageView
+import android.widget.TextView
+import androidx.databinding.BindingAdapter
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.convertDurationToFormatted
+import com.example.android.trackmysleepquality.convertNumericQualityToString
+import com.example.android.trackmysleepquality.database.SleepNight
+
+
+@BindingAdapter("sleepDurationFormatted")
+fun TextView.setSleepDurationFormatted(item: SleepNight?) {
+    item?.let {
+        text = convertDurationToFormatted(item.startTimeMilli, item.endTimeMilli, context.resources)
+    }
+}
+
+
+@BindingAdapter("sleepQualityString")
+fun TextView.setSleepQualityString(item: SleepNight?) {
+    item?.let {
+        text = convertNumericQualityToString(item.sleepQuality, context.resources)
+    }
+}
+
+
+@BindingAdapter("sleepImage")
+fun ImageView.setSleepImage(item: SleepNight?) {
+    item?.let {
+        setImageResource(when (item.sleepQuality) {
+            0 -> R.drawable.ic_sleep_0
+            1 -> R.drawable.ic_sleep_1
+            2 -> R.drawable.ic_sleep_2
+
+            3 -> R.drawable.ic_sleep_3
+
+            4 -> R.drawable.ic_sleep_4
+            5 -> R.drawable.ic_sleep_5
+            else -> R.drawable.ic_sleep_active
+        })
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepNightAdapter.kt

@@ -0,0 +1,70 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.trackmysleepquality.database.SleepNight
+import com.example.android.trackmysleepquality.databinding.ListItemSleepNightBinding
+
+class SleepNightAdapter(val clickListener: SleepNightListener) : ListAdapter<SleepNight, SleepNightAdapter.ViewHolder>(SleepNightDiffCallback()) {
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        holder.bind(getItem(position)!!, clickListener)
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        return ViewHolder.from(parent)
+    }
+
+    class ViewHolder private constructor(val binding: ListItemSleepNightBinding) : RecyclerView.ViewHolder(binding.root){
+
+        fun bind(item: SleepNight, clickListener: SleepNightListener) {
+            binding.sleep = item
+            binding.clickListener = clickListener
+            binding.executePendingBindings()
+        }
+
+        companion object {
+            fun from(parent: ViewGroup): ViewHolder {
+                val layoutInflater = LayoutInflater.from(parent.context)
+                val binding = ListItemSleepNightBinding.inflate(layoutInflater, parent, false)
+                return ViewHolder(binding)
+            }
+        }
+    }
+}
+
+
+class SleepNightDiffCallback : DiffUtil.ItemCallback<SleepNight>() {
+
+    override fun areItemsTheSame(oldItem: SleepNight, newItem: SleepNight): Boolean {
+        return oldItem.nightId == newItem.nightId
+    }
+
+    override fun areContentsTheSame(oldItem: SleepNight, newItem: SleepNight): Boolean {
+        return oldItem == newItem
+    }
+}
+
+
+class SleepNightListener(val clickListener: (sleepId: Long) -> Unit) {
+    fun onClick(night: SleepNight) = clickListener(night.nightId)
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerFragment.kt

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
+import androidx.navigation.fragment.findNavController
+import androidx.recyclerview.widget.GridLayoutManager
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.database.SleepDatabase
+import com.example.android.trackmysleepquality.databinding.FragmentSleepTrackerBinding
+import com.google.android.material.snackbar.Snackbar
+
+/**
+ * A fragment with buttons to record start and end times for sleep, which are saved in
+ * a database. Cumulative data is displayed in a simple scrollable TextView.
+ * (Because we have not learned about RecyclerView yet.)
+ * The Clear button will clear all data from the database.
+ */
+class SleepTrackerFragment : Fragment() {
+
+    /**
+     * Called when the Fragment is ready to display content to the screen.
+     *
+     * This function uses DataBindingUtil to inflate R.layout.fragment_sleep_quality.
+     *
+     * It is also responsible for passing the [SleepTrackerViewModel] to the
+     * [FragmentSleepTrackerBinding] generated by DataBinding. This will allow DataBinding
+     * to use the [LiveData] on our ViewModel.
+     */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+
+        // Get a reference to the binding object and inflate the fragment views.
+        val binding: FragmentSleepTrackerBinding = DataBindingUtil.inflate(
+                inflater, R.layout.fragment_sleep_tracker, container, false)
+
+        val application = requireNotNull(this.activity).application
+
+        // Create an instance of the ViewModel Factory.
+        val dataSource = SleepDatabase.getInstance(application).sleepDatabaseDao
+        val viewModelFactory = SleepTrackerViewModelFactory(dataSource, application)
+
+        // Get a reference to the ViewModel associated with this fragment.
+        val sleepTrackerViewModel =
+                ViewModelProviders.of(
+                        this, viewModelFactory).get(SleepTrackerViewModel::class.java)
+
+        // To use the View Model with data binding, you have to explicitly
+        // give the binding object a reference to it.
+        binding.sleepTrackerViewModel = sleepTrackerViewModel
+
+        val adapter = SleepNightAdapter(SleepNightListener { nightId ->
+            //Toast.makeText(context, "${nightId}", Toast.LENGTH_LONG).show()
+            sleepTrackerViewModel.onSleepNightClicked(nightId)
+        })
+        binding.sleepList.adapter = adapter
+
+
+        sleepTrackerViewModel.nights.observe(viewLifecycleOwner, Observer {
+            it?.let {
+                adapter.submitList(it)
+            }
+        })
+
+        // Specify the current activity as the lifecycle owner of the binding.
+        // This is necessary so that the binding can observe LiveData updates.
+        binding.setLifecycleOwner(this)
+
+        // Add an Observer on the state variable for showing a Snackbar message
+        // when the CLEAR button is pressed.
+        sleepTrackerViewModel.showSnackBarEvent.observe(this, Observer {
+            if (it == true) { // Observed state is true.
+                Snackbar.make(
+                        activity!!.findViewById(android.R.id.content),
+                        getString(R.string.cleared_message),
+                        Snackbar.LENGTH_SHORT // How long to display the message.
+                ).show()
+                // Reset state to make sure the toast is only shown once, even if the device
+                // has a configuration change.
+                sleepTrackerViewModel.doneShowingSnackbar()
+            }
+        })
+
+        // Add an Observer on the state variable for Navigating when STOP button is pressed.
+        sleepTrackerViewModel.navigateToSleepQuality.observe(this, Observer { night ->
+            night?.let {
+                // We need to get the navController from this, because button is not ready, and it
+                // just has to be a view. For some reason, this only matters if we hit stop again
+                // after using the back button, not if we hit stop and choose a quality.
+                // Also, in the Navigation Editor, for Quality -> Tracker, check "Inclusive" for
+                // popping the stack to get the correct behavior if we press stop multiple times
+                // followed by back.
+                // Also: https://stackoverflow.com/questions/28929637/difference-and-uses-of-oncreate-oncreateview-and-onactivitycreated-in-fra
+                this.findNavController().navigate(
+                        SleepTrackerFragmentDirections
+                                .actionSleepTrackerFragmentToSleepQualityFragment(night.nightId))
+                // Reset state to make sure we only navigate once, even if the device
+                // has a configuration change.
+                sleepTrackerViewModel.doneNavigating()
+            }
+        })
+
+        // Add an Observer on the state variable for Navigating when and item is clicked.
+        sleepTrackerViewModel.navigateToSleepDetail.observe(this, Observer { night ->
+            night?.let {
+
+                this.findNavController().navigate(
+                        SleepTrackerFragmentDirections
+                                .actionSleepTrackerFragmentToSleepDetailFragment(night))
+                sleepTrackerViewModel.onSleepDetailNavigated()
+            }
+        })
+
+        val manager = GridLayoutManager(activity, 3)
+        binding.sleepList.layoutManager = manager
+
+        return binding.root
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerViewModel.kt

@@ -0,0 +1,263 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.app.Application
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations
+import androidx.lifecycle.ViewModel
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+import com.example.android.trackmysleepquality.database.SleepNight
+import com.example.android.trackmysleepquality.formatNights
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * ViewModel for SleepTrackerFragment.
+ */
+class SleepTrackerViewModel(
+        dataSource: SleepDatabaseDao,
+        application: Application) : ViewModel() {
+
+    /**
+     * Hold a reference to SleepDatabase via SleepDatabaseDao.
+     */
+    val database = dataSource
+
+    /** Coroutine variables */
+
+    /**
+     * viewModelJob allows us to cancel all coroutines started by this ViewModel.
+     */
+    private var viewModelJob = Job()
+
+    /**
+     * A [CoroutineScope] keeps track of all coroutines started by this ViewModel.
+     *
+     * Because we pass it [viewModelJob], any coroutine started in this uiScope can be cancelled
+     * by calling `viewModelJob.cancel()`
+     *
+     * By default, all coroutines started in uiScope will launch in [Dispatchers.Main] which is
+     * the main thread on Android. This is a sensible default because most coroutines started by
+     * a [ViewModel] update the UI after performing some processing.
+     */
+    private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
+
+    private var tonight = MutableLiveData<SleepNight?>()
+
+    val nights = database.getAllNights()
+
+    /**
+     * Converted nights to Spanned for displaying.
+     */
+    val nightsString = Transformations.map(nights) { nights ->
+        formatNights(nights, application.resources)
+    }
+
+    /**
+     * If tonight has not been set, then the START button should be visible.
+     */
+    val startButtonVisible = Transformations.map(tonight) {
+        null == it
+    }
+
+    /**
+     * If tonight has been set, then the STOP button should be visible.
+     */
+    val stopButtonVisible = Transformations.map(tonight) {
+        null != it
+    }
+
+    /**
+     * If there are any nights in the database, show the CLEAR button.
+     */
+    val clearButtonVisible = Transformations.map(nights) {
+        it?.isNotEmpty()
+    }
+
+    /**
+     * Request a toast by setting this value to true.
+     *
+     * This is private because we don't want to expose setting this value to the Fragment.
+     */
+    private var _showSnackbarEvent = MutableLiveData<Boolean?>()
+
+    /**
+     * If this is true, immediately `show()` a toast and call `doneShowingSnackbar()`.
+     */
+    val showSnackBarEvent: LiveData<Boolean?>
+        get() = _showSnackbarEvent
+
+    /**
+     * Variable that tells the Fragment to navigate to a specific [SleepQualityFragment]
+     *
+     * This is private because we don't want to expose setting this value to the Fragment.
+     */
+    private val _navigateToSleepQuality = MutableLiveData<SleepNight>()
+
+    /**
+     * If this is non-null, immediately navigate to [SleepQualityFragment] and call [doneNavigating]
+     */
+    val navigateToSleepQuality: LiveData<SleepNight>
+        get() = _navigateToSleepQuality
+
+    /**
+     * Call this immediately after calling `show()` on a toast.
+     *
+     * It will clear the toast request, so if the user rotates their phone it won't show a duplicate
+     * toast.
+     */
+    fun doneShowingSnackbar() {
+        _showSnackbarEvent.value = null
+    }
+
+    /**
+     * Call this immediately after navigating to [SleepQualityFragment]
+     *
+     * It will clear the navigation request, so if the user rotates their phone it won't navigate
+     * twice.
+     */
+    fun doneNavigating() {
+        _navigateToSleepQuality.value = null
+    }
+
+    /**
+     * Navigation for the SleepDetail fragment.
+     */
+    private val _navigateToSleepDetail = MutableLiveData<Long>()
+    val navigateToSleepDetail
+        get() = _navigateToSleepDetail
+
+    fun onSleepNightClicked(id: Long) {
+        _navigateToSleepDetail.value = id
+    }
+
+    fun onSleepDetailNavigated() {
+        _navigateToSleepDetail.value = null
+    }
+
+    init {
+        initializeTonight()
+    }
+
+    private fun initializeTonight() {
+        uiScope.launch {
+            tonight.value = getTonightFromDatabase()
+        }
+    }
+
+    /**
+     *  Handling the case of the stopped app or forgotten recording,
+     *  the start and end times will be the same.j
+     *
+     *  If the start time and end time are not the same, then we do not have an unfinished
+     *  recording.
+     */
+    private suspend fun getTonightFromDatabase(): SleepNight? {
+        return withContext(Dispatchers.IO) {
+            var night = database.getTonight()
+            if (night?.endTimeMilli != night?.startTimeMilli) {
+                night = null
+            }
+            night
+        }
+    }
+
+    private suspend fun insert(night: SleepNight) {
+        withContext(Dispatchers.IO) {
+            database.insert(night)
+        }
+    }
+
+    private suspend fun update(night: SleepNight) {
+        withContext(Dispatchers.IO) {
+            database.update(night)
+        }
+    }
+
+    private suspend fun clear() {
+        withContext(Dispatchers.IO) {
+            database.clear()
+        }
+    }
+
+    /**
+     * Executes when the START button is clicked.
+     */
+    fun onStart() {
+        uiScope.launch {
+            // Create a new night, which captures the current time,
+            // and insert it into the database.
+            val newNight = SleepNight()
+
+            insert(newNight)
+
+            tonight.value = getTonightFromDatabase()
+        }
+    }
+
+    /**
+     * Executes when the STOP button is clicked.
+     */
+    fun onStop() {
+        uiScope.launch {
+            // In Kotlin, the return@label syntax is used for specifying which function among
+            // several nested ones this statement returns from.
+            // In this case, we are specifying to return from launch().
+            val oldNight = tonight.value ?: return@launch
+
+            // Update the night in the database to add the end time.
+            oldNight.endTimeMilli = System.currentTimeMillis()
+
+            update(oldNight)
+
+            // Set state to navigate to the SleepQualityFragment.
+            _navigateToSleepQuality.value = oldNight
+        }
+    }
+
+    /**
+     * Executes when the CLEAR button is clicked.
+     */
+    fun onClear() {
+        uiScope.launch {
+            // Clear the database table.
+            clear()
+
+            // And clear tonight since it's no longer in the database
+            tonight.value = null
+
+            // Show a snackbar message, because it's friendly.
+            _showSnackbarEvent.value = true
+        }
+    }
+
+    /**
+     * Called when the ViewModel is dismantled.
+     * At this point, we want to cancel all coroutines;
+     * otherwise we end up with processes that have nowhere to return to
+     * using memory and resources.
+     */
+    override fun onCleared() {
+        super.onCleared()
+        viewModelJob.cancel()
+    }
+}

RecyclerViewClickHandler/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerViewModelFactory.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+
+import android.app.Application
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+
+/**
+ * This is pretty much boiler plate code for a ViewModel Factory.
+ *
+ * Provides the SleepDatabaseDao and context to the ViewModel.
+ */
+class SleepTrackerViewModelFactory(
+        private val dataSource: SleepDatabaseDao,
+        private val application: Application) : ViewModelProvider.Factory {
+    @Suppress("unchecked_cast")
+    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+        if (modelClass.isAssignableFrom(SleepTrackerViewModel::class.java)) {
+            return SleepTrackerViewModel(dataSource, application) as T
+        }
+        throw IllegalArgumentException("Unknown ViewModel class")
+    }
+}

RecyclerViewClickHandler/app/src/main/res/anim/slide_in_right.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <translate
+        android:duration="700"
+        android:fromXDelta="100%"
+        android:fromYDelta="0%"
+        android:toXDelta="0%"
+        android:toYDelta="0%" />
+</set>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_launcher_sleep_tracker_background.xml

@@ -0,0 +1,55 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportWidth="512"
+        android:viewportHeight="512">
+  <path
+      android:pathData="M0,369.07h512v142.93h-512z"
+      android:fillColor="#e0e0e0"/>
+  <path
+      android:pathData="M228.55,271.42l15.7,-30.1L225,244.55l-1,-5.78 26.34,-4.41 1,6.22 -15.6,30.07L256,267.26l1,5.79 -27.42,4.59Z"
+      android:fillColor="#757575"/>
+  <path
+      android:pathData="M271.75,215.33l41.52,-29.2 -27.86,-9 2.68,-8.35 38,12.23 -2.89,9 -41.37,29.25 29.28,9.41L308.44,237l-39.58,-12.73Z"
+      android:fillColor="#bdbdbd"/>
+  <path
+      android:pathData="M350,187.18l39.94,-79.32L339.54,117l-2.75,-15.11 68.74,-12.52 3,16.23 -39.67,79.27 52.94,-9.64 2.75,15.1 -71.57,13Z"
+      android:fillColor="#e0e0e0"/>
+  <group>
+    <clip-path android:pathData="M584.94,-624.15h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M448.55,-187.1,709.34,73.69a8.72,8.72,0,0,0,12.32,0l325.45,-325.45a8.72,8.72,0,0,0,0,-12.32L778,-533.19a18.84,18.84,0,0,0,-26.65,0L442,-241.74l-2.36,5.16A44.05,44.05,0,0,0,448.55,-187.1Z"
+        android:fillColor="#43a047"/>
+    <path
+        android:pathData="M440.25,-208.98l275.52002,275.53l335.0,-335.0l-278.15002,-278.14996l-334.26,328.40997l1.8900146,9.210007z"
+        android:fillColor="#c0ca33"/>
+    <path
+        android:pathData="M544.72,-487.03h393.36v473.76h-393.36z"
+        android:fillColor="#e6ee9c"/>
+    <path
+        android:pathData="M548.74,-506.95H930.26a8.41,8.41,0,0,1,8.41,8.41V-37.68a8.41,8.41,0,0,1,-8.41,8.41H548.74a18.19,18.19,0,0,1,-18.19,-18.19V-488.75A18.19,18.19,0,0,1,548.74,-506.95Z"
+        android:fillColor="#6ab343"/>
+  </group>
+  <group>
+    <clip-path android:pathData="M0,-624.15h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M246.59,-272.23l39.17,-11.46a3.9,3.9,0,0,0,2.67,-4.84,3.9,3.9,0,0,0,-4.84,-2.63L244,-279.58a134.83,134.83,0,0,0,-30.74,-47.09,134.89,134.89,0,0,0,-47,-30.69l11.49,-39.52a3.86,3.86,0,0,0,-2.63,-4.83,3.85,3.85,0,0,0,-4.83,2.64l-11.42,39.16c-41.3,-13.2,-86.47,-4.85,-117.17,25.89l178.9,178.87c30.72,-30.71,39,-75.79,25.93,-117.08m-211,-54.15L-93.27,-197.48a29.94,29.94,0,0,0,0,42.38l14.43,14.44,-44,44a28.1,28.1,0,0,0,0,39.7,28.12,28.12,0,0,0,39.74,0l44,-44,26.81,26.8,-44,44a28.09,28.09,0,0,0,0,39.7,28.11,28.11,0,0,0,39.74,0l44,-44L41.91,-20A30,30,0,0,0,84.3,-20L213.16,-148.87Zm180.59,90.91L203.59,-248a1.7,1.7,0,0,1,0,-2.4l1.59,-1.6a1.71,1.71,0,0,1,2.41,0l12.58,12.59a1.7,1.7,0,0,1,0,2.4l-1.59,1.59A1.7,1.7,0,0,1,216.17,-235.47Zm-81.43,-81.42,-12.58,-12.59a1.7,1.7,0,0,1,0,-2.4l1.59,-1.59a1.7,1.7,0,0,1,2.41,0l12.58,12.58a1.68,1.68,0,0,1,0,2.4l-1.59,1.6A1.71,1.71,0,0,1,134.74,-316.89Zm-99.16,-9.49L-93.27,-197.48a29.94,29.94,0,0,0,0,42.38l14.43,14.44,-44,44a28.1,28.1,0,0,0,0,39.7,28.12,28.12,0,0,0,39.74,0l44,-44,26.81,26.8,-44,44a28.09,28.09,0,0,0,0,39.7,28.11,28.11,0,0,0,39.74,0l44,-44L41.91,-20A30,30,0,0,0,84.3,-20L213.16,-148.87Z"
+        android:fillColor="#6ab343"/>
+  </group>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_launcher_sleep_tracker_foreground.xml

@@ -0,0 +1,77 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportWidth="512"
+        android:viewportHeight="512">
+  <path
+      android:pathData="M35.58,297.76l6.18,-7.64l98.76,-8.5l100.14,101.33l-20,86.04l-7.5,6.29l-126.86,-7.63l-50.72,-169.89z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M389,302.51q-28.14,0 -47.68,19.54T321.8,369.73q0,28.15 19.55,48.08T389,437.74q28.14,0 48.08,-19.93T457,369.73q0,-28.14 -19.93,-47.68T389,302.51Z"
+      android:fillColor="#6ab343"/>
+  <path
+      android:pathData="M389.17,326.32a43.23,43.23 0,0 0,-43.55 43.55A42.84,42.84 0,0 0,358.28 401a41.6,41.6 0,0 0,30.89 12.92,44.09 44.09,0 0,0 44.05,-44.06A41.61,41.61 0,0 0,420.31 339,42.91 42.91,0 0,0 389.17,326.32Z"
+      android:fillColor="#f5f5f5"/>
+  <path
+      android:pathData="M389.4,363.79L389.4,340.35"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
+      android:fillColor="#00000000"
+      android:strokeColor="#6ab343"
+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M394.5,373.69L412.12,384.46"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
+      android:fillColor="#00000000"
+      android:strokeColor="#6ab343"
+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M389.39,363.79a6.25,6.25 0,0 0,-6.3 6.3,6.2 6.2,0 0,0 1.83,4.5 6,6 0,0 0,4.47 1.87,6.37 6.37,0 0,0 6.36,-6.37 6,6 0,0 0,-1.86 -4.47A6.21,6.21 0,0 0,389.39 363.79Z"
+      android:strokeWidth="7"
+      android:fillColor="#f5f5f5"
+      android:strokeColor="#6ab343"/>
+  <group>
+    <clip-path android:pathData="M584.94,0h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M448.55,437.05,709.34,697.84a8.72,8.72,0,0,0,12.32,0l325.45,-325.45a8.72,8.72,0,0,0,0,-12.32L778,91a18.84,18.84,0,0,0,-26.65,0L442,382.4l-2.36,5.16A44.07,44.07,0,0,0,448.55,437.05Z"
+        android:fillColor="#43a047"/>
+    <path
+        android:pathData="M440.25,415.17l275.52002,275.52l335.0,-334.99l-278.15002,-278.15002l-334.26,328.40002l1.8900146,9.220001z"
+        android:fillColor="#c0ca33"/>
+    <path
+        android:pathData="M544.72,137.12h393.36v473.76h-393.36z"
+        android:fillColor="#e6ee9c"/>
+    <path
+        android:pathData="M548.74,117.2H930.26a8.41,8.41,0,0,1,8.41,8.41V586.47a8.41,8.41,0,0,1,-8.41,8.41H548.74a18.19,18.19,0,0,1,-18.19,-18.19V135.4a18.19,18.19,0,0,1,18.19,-18.19Z"
+        android:fillColor="#6ab343"/>
+    <path
+        android:pathData="M601.64,-8.95h13.65v477.68h-13.65z"
+        android:fillColor="#43a047"/>
+    <path
+        android:pathData="M612.29,-1.71h6.82v477.68h-6.82z"
+        android:fillColor="#66bb6a"/>
+  </group>
+  <group>
+    <clip-path android:pathData="M0,0h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M246.59,351.91l39.17,-11.45a3.89,3.89,0,1,0,-2.17,-7.47L244,344.56a136.82,136.82,0,0,0,-77.69,-77.77l11.49,-39.53a3.89,3.89,0,1,0,-7.46,-2.19l-11.42,39.16c-41.3,-13.19,-86.47,-4.84,-117.17,25.89L220.66,469c30.72,-30.71,39,-75.78,25.93,-117.08m-211,-54.15L-93.27,426.67a29.94,29.94,0,0,0,0,42.38l14.43,14.43,-44,44a28.11,28.11,0,0,0,0,39.71,28.12,28.12,0,0,0,39.74,0l44,-44L-12.31,550l-44,44a28.1,28.1,0,0,0,0,39.71,28.1,28.1,0,0,0,39.74,0l44,-44,14.49,14.47a30,30,0,0,0,42.39,0l128.86,-128.9Zm180.59,90.92L203.59,376.1a1.71,1.71,0,0,1,0,-2.41l1.59,-1.59a1.71,1.71,0,0,1,2.41,0l12.58,12.58a1.71,1.71,0,0,1,0,2.41l-1.59,1.59A1.7,1.7,0,0,1,216.17,388.68Zm-81.43,-81.43,-12.58,-12.58a1.7,1.7,0,0,1,0,-2.4l1.59,-1.6a1.71,1.71,0,0,1,2.41,0l12.58,12.59a1.68,1.68,0,0,1,0,2.4l-1.59,1.59A1.7,1.7,0,0,1,134.74,307.25Zm-99.16,-9.49L-93.27,426.67a29.94,29.94,0,0,0,0,42.38l14.43,14.43,-44,44a28.11,28.11,0,0,0,0,39.71,28.12,28.12,0,0,0,39.74,0l44,-44L-12.31,550l-44,44a28.1,28.1,0,0,0,0,39.71,28.1,28.1,0,0,0,39.74,0l44,-44,14.49,14.47a30,30,0,0,0,42.39,0l128.86,-128.9Z"
+        android:fillColor="#6ab343"/>
+  </group>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_0.xml

@@ -0,0 +1,28 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#fff" android:pathData="M81.158,261.465L145.387,272.79A5.49,5.49 55,0 1,149.84 279.15L149.832,279.199A5.49,5.49 55,0 1,143.472 283.652L79.243,272.327A5.49,5.49 55,0 1,74.789 265.967L74.798,265.918A5.49,5.49 55,0 1,81.158 261.465z"/>
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+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_1.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#fff" android:pathData="M80.313,264.221L145.284,269.905A5.49,5.49 50,0 1,150.275 275.853L150.271,275.903A5.49,5.49 50,0 1,144.323 280.893L79.351,275.209A5.49,5.49 50,0 1,74.361 269.261L74.365,269.212A5.49,5.49 50,0 1,80.313 264.221z"/>
+    <path android:fillColor="#fff" android:pathData="M217.037,269.907L282.009,264.223A5.49,5.49 130,0 1,287.956 269.213L287.961,269.263A5.49,5.49 130,0 1,282.97 275.211L217.998,280.895A5.49,5.49 130,0 1,212.051 275.904L212.046,275.855A5.49,5.49 130,0 1,217.037 269.907z"/>
+    <path android:fillColor="#00000000"
+        android:pathData="M92.91,395.3c19.86,-26.3 54.92,-43.94 87.69,-43.94 33.08,0 68.5,18 88.26,44.69"
+        android:strokeColor="#fff" android:strokeLineCap="round" android:strokeWidth="20"/>
+    <path android:fillColor="#eee" android:pathData="M398.31,101.69m-101.69,0a101.69,101.69 0,1 1,203.38 0a101.69,101.69 0,1 1,-203.38 0"/>
+    <path android:fillColor="#eee" android:pathData="M267.86,57.09m-24.76,0a24.76,24.76 0,1 1,49.52 0a24.76,24.76 0,1 1,-49.52 0"/>
+    <path android:fillColor="#eee" android:pathData="M224.93,85.36m-16.33,0a16.33,16.33 0,1 1,32.66 0a16.33,16.33 0,1 1,-32.66 0"/>
+    <path android:fillColor="#eee" android:pathData="M217.77,120.19m-9.17,0a9.17,9.17 0,1 1,18.34 0a9.17,9.17 0,1 1,-18.34 0"/>
+    <path android:fillColor="#6ab343" android:pathData="M400.67,75.13 L385.22,86.38l-9.9,-15.15 30.15,-21.75h14.85v102.6H400.67Z"/>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_2.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#fff" android:pathData="M79.71,267.04L144.93,267.04A5.49,5.49 0,0 1,150.42 272.53L150.42,272.58A5.49,5.49 0,0 1,144.93 278.07L79.71,278.07A5.49,5.49 0,0 1,74.22 272.58L74.22,272.53A5.49,5.49 0,0 1,79.71 267.04z"/>
+    <path android:fillColor="#fff" android:pathData="M217.39,267.04L282.61,267.04A5.49,5.49 0,0 1,288.1 272.53L288.1,272.58A5.49,5.49 0,0 1,282.61 278.07L217.39,278.07A5.49,5.49 0,0 1,211.9 272.58L211.9,272.53A5.49,5.49 0,0 1,217.39 267.04z"/>
+    <path android:fillColor="#00000000"
+        android:pathData="M268.86,383.11L92.91,382.36"
+        android:strokeColor="#fff" android:strokeLineCap="round" android:strokeWidth="20"/>
+    <path android:fillColor="#eee" android:pathData="M398.31,101.69m-101.69,0a101.69,101.69 0,1 1,203.38 0a101.69,101.69 0,1 1,-203.38 0"/>
+    <path android:fillColor="#eee" android:pathData="M267.86,57.09m-24.76,0a24.76,24.76 0,1 1,49.52 0a24.76,24.76 0,1 1,-49.52 0"/>
+    <path android:fillColor="#eee" android:pathData="M224.93,85.36m-16.33,0a16.33,16.33 0,1 1,32.66 0a16.33,16.33 0,1 1,-32.66 0"/>
+    <path android:fillColor="#eee" android:pathData="M217.77,120.19m-9.17,0a9.17,9.17 0,1 1,18.34 0a9.17,9.17 0,1 1,-18.34 0"/>
+    <path android:fillColor="#6ab343" android:pathData="M366.07,134.23l19.13,-19.12q14.18,-14.17 18.22,-18.53a48.84,48.84 0,0 0,7.43 -9.75,18.89 18.89,0 0,0 2,-8.85 11.59,11.59 0,0 0,-3.9 -8.85q-3.9,-3.6 -10.35,-3.6a14.44,14.44 0,0 0,-10.2 3.6,19.9 19.9,0 0,0 -5.55,9l-17.7,-7.35a31.77,31.77 0,0 1,6.08 -11.32,33.4 33.4,0 0,1 11.47,-8.93 36.54,36.54 0,0 1,16.2 -3.45,38.19 38.19,0 0,1 17.85,4 29.55,29.55 0,0 1,11.85 10.8,28.48 28.48,0 0,1 4.2,15.22q0,16.65 -16.2,32.55 -6.6,6.47 -24.45,24.3l0.45,0.9h41.55v17.25h-68.1Z"/>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_3.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#eee" android:pathData="M398.31,101.69m-101.69,0a101.69,101.69 0,1 1,203.38 0a101.69,101.69 0,1 1,-203.38 0"/>
+    <path android:fillColor="#eee" android:pathData="M267.86,57.09m-24.76,0a24.76,24.76 0,1 1,49.52 0a24.76,24.76 0,1 1,-49.52 0"/>
+    <path android:fillColor="#eee" android:pathData="M224.93,85.36m-16.33,0a16.33,16.33 0,1 1,32.66 0a16.33,16.33 0,1 1,-32.66 0"/>
+    <path android:fillColor="#eee" android:pathData="M217.77,120.19m-9.17,0a9.17,9.17 0,1 1,18.34 0a9.17,9.17 0,1 1,-18.34 0"/>
+    <path android:fillColor="#6ab343" android:pathData="M377,147.58q-10,-6.89 -13.73,-20.1l18.6,-7.35q1.8,7.37 6.45,11.33a17.37,17.37 0,0 0,11.7 4,17 17,0 0,0 11.18,-3.9 12.88,12.88 0,0 0,-0.3 -20.17q-5,-3.83 -13.58,-3.83h-8.85V89.68h8.1a18.54,18.54 0,0 0,11.18 -3.3c3.05,-2.19 4.57,-5.4 4.57,-9.6a10.72,10.72 0,0 0,-3.75 -8.4,14 14,0 0,0 -9.6,-3.3 14.49,14.49 0,0 0,-9.9 3.3,17.57 17.57,0 0,0 -5.25,8.25l-17.85,-7.35a33.92,33.92 0,0 1,11.63 -15.6q8.47,-6.59 21.52,-6.6a39.56,39.56 0,0 1,17.18 3.6A28.64,28.64 0,0 1,428 60.51a24.51,24.51 0,0 1,4.2 14,25.17 25.17,0 0,1 -3.82,14.1 23.8,23.8 0,0 1,-9.23 8.55v1.2a27.18,27.18 0,0 1,12.15 9.45,26 26,0 0,1 4.65,15.6 28.87,28.87 0,0 1,-4.5 15.9,30.82 30.82,0 0,1 -12.67,11.1 41.9,41.9 0,0 1,-18.83 4A39.46,39.46 0,0 1,377 147.58Z"/>
+    <path android:fillColor="#fff" android:pathData="M79.71,267.04L144.93,267.04A5.49,5.49 0,0 1,150.42 272.53L150.42,272.58A5.49,5.49 0,0 1,144.93 278.07L79.71,278.07A5.49,5.49 0,0 1,74.22 272.58L74.22,272.53A5.49,5.49 0,0 1,79.71 267.04z"/>
+    <path android:fillColor="#fff" android:pathData="M217.39,267.04L282.61,267.04A5.49,5.49 0,0 1,288.1 272.53L288.1,272.58A5.49,5.49 0,0 1,282.61 278.07L217.39,278.07A5.49,5.49 0,0 1,211.9 272.58L211.9,272.53A5.49,5.49 0,0 1,217.39 267.04z"/>
+    <path android:fillColor="#00000000"
+        android:pathData="M268.86,377.57c-19.87,8.69 -54.93,14.52 -87.7,14.52 -33.08,0 -68.49,-5.94 -88.25,-14.77"
+        android:strokeColor="#fff" android:strokeLineCap="round" android:strokeWidth="20"/>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_4.xml

@@ -0,0 +1,30 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#fff" android:pathData="M79.351,269.907L144.323,264.222A5.49,5.49 130,0 1,150.27 269.213L150.275,269.263A5.49,5.49 130,0 1,145.284 275.21L80.312,280.895A5.49,5.49 130,0 1,74.364 275.904L74.36,275.854A5.49,5.49 130,0 1,79.351 269.907z"/>
+    <path android:fillColor="#fff" android:pathData="M218.066,265.855L283.286,271.725A5.512,5.512 50.143,0 1,288.282 277.709L288.278,277.759A5.512,5.512 50.143,0 1,282.294 282.755L217.074,276.885A5.512,5.512 50.143,0 1,212.078 270.901L212.082,270.851A5.512,5.512 50.143,0 1,218.066 265.855z"/>
+    <path android:fillColor="#00000000"
+        android:pathData="M268.86,363.11c-19.87,26.3 -54.93,43.94 -87.7,43.94 -33.08,0 -68.49,-18 -88.25,-44.69"
+        android:strokeColor="#fff" android:strokeLineCap="round" android:strokeWidth="20"/>
+    <path android:fillColor="#eee" android:pathData="M398.31,101.69m-101.69,0a101.69,101.69 0,1 1,203.38 0a101.69,101.69 0,1 1,-203.38 0"/>
+    <path android:fillColor="#eee" android:pathData="M267.86,57.09m-24.76,0a24.76,24.76 0,1 1,49.52 0a24.76,24.76 0,1 1,-49.52 0"/>
+    <path android:fillColor="#eee" android:pathData="M224.93,85.36m-16.33,0a16.33,16.33 0,1 1,32.66 0a16.33,16.33 0,1 1,-32.66 0"/>
+    <path android:fillColor="#eee" android:pathData="M217.77,120.19m-9.17,0a9.17,9.17 0,1 1,18.34 0a9.17,9.17 0,1 1,-18.34 0"/>
+    <path android:fillColor="#6ab343" android:pathData="M402.17,133.18L354.92,133.18v-15.9l45.6,-67.8h21.3v65.4h12.75v18.3L421.82,133.18v18.9L402.17,152.08ZM402.17,114.88L402.17,78.73L401,78.73l-24.3,36.15Z"/>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_5.xml

@@ -0,0 +1,28 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:height="24dp" android:viewportHeight="500"
+    android:viewportWidth="500" android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#6ab343" android:pathData="M181.16,316.18m-181.7,0a181.7,181.7 0,1 1,363.4 0a181.7,181.7 0,1 1,-363.4 0"/>
+    <path android:fillColor="#fff" android:pathData="M79.25,272.792L143.479,261.466A5.49,5.49 125,0 1,149.839 265.919L149.848,265.969A5.49,5.49 125,0 1,145.395 272.329L81.165,283.654A5.49,5.49 125,0 1,74.805 279.201L74.797,279.151A5.49,5.49 125,0 1,79.25 272.792z"/>
+    <path android:fillColor="#fff" android:pathData="M218.846,261.462L283.076,272.788A5.49,5.49 55,0 1,287.529 279.148L287.52,279.197A5.49,5.49 55,0 1,281.16 283.65L216.931,272.325A5.49,5.49 55,0 1,212.478 265.965L212.486,265.916A5.49,5.49 55,0 1,218.846 261.462z"/>
+    <path android:fillColor="#fff" android:pathData="M274.74,337.67a9.55,9.55 0,0 1,9.41 11.11c-7.36,44.12 -57.39,78.27 -103,78.27s-95.63,-34.15 -103,-78.27a9.55,9.55 0,0 1,9.41 -11.11Z"/>
+    <path android:fillColor="#eee" android:pathData="M398.31,101.69m-101.69,0a101.69,101.69 0,1 1,203.38 0a101.69,101.69 0,1 1,-203.38 0"/>
+    <path android:fillColor="#eee" android:pathData="M267.86,57.09m-24.76,0a24.76,24.76 0,1 1,49.52 0a24.76,24.76 0,1 1,-49.52 0"/>
+    <path android:fillColor="#eee" android:pathData="M224.93,85.36m-16.33,0a16.33,16.33 0,1 1,32.66 0a16.33,16.33 0,1 1,-32.66 0"/>
+    <path android:fillColor="#eee" android:pathData="M217.77,120.19m-9.17,0a9.17,9.17 0,1 1,18.34 0a9.17,9.17 0,1 1,-18.34 0"/>
+    <path android:fillColor="#6ab343" android:pathData="M383.77,151.41a35.84,35.84 0,0 1,-13.12 -9.3,33.67 33.67,0 0,1 -7.73,-15.38l17.7,-6.9a23.14,23.14 0,0 0,6.6 12.08,17 17,0 0,0 12,4.42 16.24,16.24 0,0 0,12 -4.8,16.43 16.43,0 0,0 4.8,-12.15 16.66,16.66 0,0 0,-4.72 -12.07,16.1 16.1,0 0,0 -12.08,-4.88 17.71,17.71 0,0 0,-8.17 1.88,19.05 19.05,0 0,0 -6.23,5l-19.05,-8.55 5.85,-51.3h57.9V66.73H388l-3.75,24 1.2,0.3a27.32,27.32 0,0 1,17.85 -6.15,31.18 31.18,0 0,1 16,4.35 32.65,32.65 0,0 1,11.92 12.23,35.49 35.49,0 0,1 4.5,17.92A35.22,35.22 0,0 1,431 137.53,32.81 32.81,0 0,1 418.12,150a38.51,38.51 0,0 1,-18.75 4.5A40.73,40.73 0,0 1,383.77 151.41Z"/>
+</vector>

RecyclerViewClickHandler/app/src/main/res/drawable/ic_sleep_active.xml

@@ -0,0 +1,77 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportWidth="512"
+        android:viewportHeight="512">
+  <path
+      android:pathData="M35.58,297.76l6.18,-7.64l98.76,-8.5l100.14,101.33l-20,86.04l-7.5,6.29l-126.86,-7.63l-50.72,-169.89z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M389,302.51q-28.14,0 -47.68,19.54T321.8,369.73q0,28.15 19.55,48.08T389,437.74q28.14,0 48.08,-19.93T457,369.73q0,-28.14 -19.93,-47.68T389,302.51Z"
+      android:fillColor="#6ab343"/>
+  <path
+      android:pathData="M389.17,326.32a43.23,43.23 0,0 0,-43.55 43.55A42.84,42.84 0,0 0,358.28 401a41.6,41.6 0,0 0,30.89 12.92,44.09 44.09,0 0,0 44.05,-44.06A41.61,41.61 0,0 0,420.31 339,42.91 42.91,0 0,0 389.17,326.32Z"
+      android:fillColor="#f5f5f5"/>
+  <path
+      android:pathData="M389.4,363.79L389.4,340.35"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
+      android:fillColor="#00000000"
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+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M394.5,373.69L412.12,384.46"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
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+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M389.39,363.79a6.25,6.25 0,0 0,-6.3 6.3,6.2 6.2,0 0,0 1.83,4.5 6,6 0,0 0,4.47 1.87,6.37 6.37,0 0,0 6.36,-6.37 6,6 0,0 0,-1.86 -4.47A6.21,6.21 0,0 0,389.39 363.79Z"
+      android:strokeWidth="7"
+      android:fillColor="#f5f5f5"
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+  <group>
+    <clip-path android:pathData="M584.94,0h512v512h-512z M 0,0"/>
+    <path
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+    <path
+        android:pathData="M612.29,-1.71h6.82v477.68h-6.82z"
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+  </group>
+  <group>
+    <clip-path android:pathData="M0,0h512v512h-512z M 0,0"/>
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+        android:fillColor="#6ab343"/>
+  </group>
+</vector>

RecyclerViewClickHandler/app/src/main/res/font/roboto.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<font-family xmlns:app="http://schemas.android.com/apk/res-auto"
+        app:fontProviderAuthority="com.google.android.gms.fonts"
+        app:fontProviderPackage="com.google.android.gms"
+        app:fontProviderQuery="Roboto"
+        app:fontProviderCerts="@array/com_google_android_gms_fonts_certs">
+</font-family>

RecyclerViewClickHandler/app/src/main/res/layout/activity_main.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<!-- The merge tag can be used to eliminate redundant layouts when
+     including layouts, and it's a good idea to use it.
+     See: https://developer.android.com/training/improving-layouts/reusing-layouts -->
+
+<merge xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <fragment
+        android:id="@+id/nav_host_fragment"
+        android:name="androidx.navigation.fragment.NavHostFragment"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:defaultNavHost="true"
+        app:navGraph="@navigation/navigation" />
+
+</merge>

RecyclerViewClickHandler/app/src/main/res/layout/fragment_sleep_detail.xml

@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+    <!-- Data to make available to the XML via data binding. In this case,
+ the whole ViewModel, so that we can access the LiveData,
+ click handlers, and state variables. -->
+    <data>
+        <variable
+            name="sleepDetailViewModel"
+            type="com.example.android.trackmysleepquality.sleepdetail.SleepDetailViewModel" />
+    </data>
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".sleepdetail.SleepDetailFragment">
+
+        <ImageView
+            android:id="@+id/quality_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:layout_marginStart="8dp"
+            android:layout_marginTop="56dp"
+            android:layout_marginEnd="8dp"
+            app:sleepImage="@{sleepDetailViewModel.night}"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <TextView
+            android:id="@+id/quality_string"
+            android:layout_width="wrap_content"
+            android:layout_height="20dp"
+            android:layout_marginStart="8dp"
+            android:layout_marginTop="100dp"
+            android:layout_marginEnd="8dp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/quality_image"
+            app:sleepQualityString="@{sleepDetailViewModel.night}" />
+
+        <TextView
+            android:id="@+id/sleep_length"
+            android:layout_width="wrap_content"
+            android:layout_height="20dp"
+            android:layout_marginStart="8dp"
+            android:layout_marginTop="32dp"
+            android:layout_marginEnd="8dp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/quality_string"
+            app:sleepDurationFormatted="@{sleepDetailViewModel.night}" />
+
+        <Button
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:layout_marginEnd="8dp"
+            android:layout_marginBottom="32dp"
+            android:onClick="@{() -> sleepDetailViewModel.onClose()}"
+            android:text="@string/close"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

RecyclerViewClickHandler/app/src/main/res/layout/fragment_sleep_quality.xml

@@ -0,0 +1,130 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<!-- Wrapping the layout into /layout to make it available with data binding. -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <!-- Data to make available to the XML via data binding. In this case,
+     the whole ViewModel, so that we can access the LiveData,
+     click handlers, and state variables. -->
+    <data>
+
+        <variable
+            name="sleepQualityViewModel"
+            type="com.example.android.trackmysleepquality.sleepquality.SleepQualityViewModel" />
+    </data>
+
+    <!-- Start of the visible fragment layout using ConstraintLayout -->
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".sleepquality.SleepQualityFragment">
+
+        <TextView
+            android:id="@+id/title_text"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="@dimen/margin"
+            android:layout_marginTop="@dimen/margin"
+            android:layout_marginBottom="@dimen/triple_margin"
+            android:fontFamily="@font/roboto"
+            android:text="@string/how_was_hour_sleep"
+            android:textSize="@dimen/title_text_size"
+            app:layout_constraintBottom_toTopOf="@+id/quality_zero_image"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <ImageView
+            android:id="@+id/quality_zero_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:layout_marginStart="@dimen/margin"
+            android:layout_marginTop="@dimen/margin"
+            android:contentDescription="@string/quality_0"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(0)}"
+            app:layout_constraintEnd_toStartOf="@+id/quality_one_image"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/title_text"
+            app:srcCompat="@drawable/ic_sleep_0" />
+
+        <ImageView
+            android:id="@+id/quality_one_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:contentDescription="@string/quality_1"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(1)}"
+            app:layout_constraintBottom_toBottomOf="@+id/quality_zero_image"
+            app:layout_constraintEnd_toStartOf="@+id/quality_two_image"
+            app:layout_constraintStart_toEndOf="@+id/quality_zero_image"
+            app:srcCompat="@drawable/ic_sleep_1" />
+
+        <ImageView
+            android:id="@+id/quality_two_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:layout_marginEnd="@dimen/margin"
+            android:contentDescription="@string/quality_2"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(2)}"
+            app:layout_constraintBottom_toBottomOf="@+id/quality_one_image"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/quality_one_image"
+            app:srcCompat="@drawable/ic_sleep_2" />
+
+        <ImageView
+            android:id="@+id/quality_three_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:layout_marginStart="@dimen/margin"
+            android:layout_marginTop="@dimen/margin"
+            android:layout_marginBottom="@dimen/margin"
+            android:contentDescription="@string/quality_3"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(3)}"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@+id/quality_four_image"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/quality_zero_image"
+            app:layout_constraintVertical_bias="0.0"
+            app:srcCompat="@drawable/ic_sleep_3" />
+
+        <ImageView
+            android:id="@+id/quality_four_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:contentDescription="@string/quality_4"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(4)}"
+            app:layout_constraintBottom_toBottomOf="@+id/quality_three_image"
+            app:layout_constraintEnd_toStartOf="@+id/quality_five_image"
+            app:layout_constraintStart_toEndOf="@+id/quality_three_image"
+            app:layout_constraintTop_toTopOf="@+id/quality_three_image"
+            app:srcCompat="@drawable/ic_sleep_4" />
+
+        <ImageView
+            android:id="@+id/quality_five_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="@dimen/icon_size"
+            android:layout_marginEnd="@dimen/margin"
+            android:contentDescription="@string/quality_5"
+            android:onClick="@{() -> sleepQualityViewModel.onSetSleepQuality(5)}"
+            app:layout_constraintBottom_toBottomOf="@+id/quality_four_image"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/quality_four_image"
+            app:layout_constraintTop_toTopOf="@+id/quality_four_image"
+            app:srcCompat="@drawable/ic_sleep_5" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

RecyclerViewClickHandler/app/src/main/res/layout/fragment_sleep_tracker.xml

@@ -0,0 +1,98 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<!-- Wrapping the layout into /layout to make it available with data binding. -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <!-- Data to make available to the XML via data binding. In this case,
+         the whole ViewModel, so that we can access the LiveData,
+         click handlers, and state variables. -->
+    <data>
+
+        <variable
+            name="sleepTrackerViewModel"
+            type="com.example.android.trackmysleepquality.sleeptracker.SleepTrackerViewModel" />
+    </data>
+
+    <!-- Start of the visible fragment layout using ConstraintLayout -->
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".sleeptracker.SleepTrackerFragment">
+
+        <!-- This lesson we will switch to RecyclerView to properly
+         display the sleep data-->
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/sleep_list"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_constraintBottom_toTopOf="@+id/clear_button"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/stop_button"/>
+
+        <!-- With data binding and LiveData, we can track the buttons' visibility states
+             from the ViewModel. The click handler is in the ViewModel as well, and
+             you can set it for the Views using this lambda pattern. -->
+
+        <Button
+            android:id="@+id/start_button"
+            style="@style/SleepButtons"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="@dimen/margin"
+            android:enabled="@{sleepTrackerViewModel.startButtonVisible}"
+            android:onClick="@{() -> sleepTrackerViewModel.onStart()}"
+            android:text="@string/start"
+            app:layout_constraintBaseline_toBaselineOf="@id/stop_button"
+            app:layout_constraintEnd_toStartOf="@+id/stop_button"
+            app:layout_constraintHorizontal_chainStyle="spread"
+            app:layout_constraintStart_toStartOf="parent" />
+
+        <Button
+            android:id="@+id/stop_button"
+            style="@style/SleepButtons"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/margin"
+            android:layout_marginEnd="@dimen/margin"
+            android:enabled="@{sleepTrackerViewModel.stopButtonVisible}"
+            android:onClick="@{() -> sleepTrackerViewModel.onStop()}"
+            android:text="@string/stop"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/start_button"
+            app:layout_constraintTop_toTopOf="parent" />
+
+        <Button
+            android:id="@+id/clear_button"
+            style="@style/SleepButtons"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="@dimen/margin"
+            android:layout_marginEnd="@dimen/margin"
+            android:layout_marginBottom="@dimen/margin"
+            android:enabled="@{sleepTrackerViewModel.clearButtonVisible}"
+            android:onClick="@{() -> sleepTrackerViewModel.onClear()}"
+            android:text="@string/clear"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

RecyclerViewClickHandler/app/src/main/res/layout/list_item_sleep_night.xml

@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <data>
+        <variable
+            name="sleep"
+            type="com.example.android.trackmysleepquality.database.SleepNight"/>
+        <variable
+            name="clickListener"
+            type="com.example.android.trackmysleepquality.sleeptracker.SleepNightListener" />
+
+    </data>
+
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:onClick="@{() -> clickListener.onClick(sleep)}">
+
+        <ImageView
+            android:id="@+id/quality_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="60dp"
+            android:layout_marginStart="16dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginBottom="8dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:srcCompat="@drawable/ic_sleep_5"
+            app:sleepImage="@{sleep}"/>
+
+        <TextView
+            android:id="@+id/quality_string"
+            android:layout_width="0dp"
+            android:layout_height="20dp"
+            android:textAlignment="center"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="@+id/quality_image"
+            app:layout_constraintHorizontal_bias="0.0"
+            app:layout_constraintStart_toStartOf="@+id/quality_image"
+            app:layout_constraintTop_toBottomOf="@+id/quality_image"
+            tools:text="Excellent!!!"
+            app:sleepQualityString="@{sleep}" />
+
+    </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

RecyclerViewClickHandler/app/src/main/res/layout/list_item_sleep_night_linear.xml

@@ -0,0 +1,71 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <data>
+        <variable
+            name="sleep"
+            type="com.example.android.trackmysleepquality.database.SleepNight"/>
+    </data>
+
+
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+        <ImageView
+            android:id="@+id/quality_image"
+            android:layout_width="@dimen/icon_size"
+            android:layout_height="60dp"
+            android:layout_marginStart="16dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginBottom="8dp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:srcCompat="@drawable/ic_sleep_5"
+            app:sleepImage="@{sleep}"/>
+
+        <TextView
+            android:id="@+id/sleep_length"
+            android:layout_width="0dp"
+            android:layout_height="20dp"
+            android:layout_marginStart="8dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginEnd="16dp"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toEndOf="@+id/quality_image"
+            app:layout_constraintTop_toTopOf="@+id/quality_image"
+            tools:text="Wednesday"
+            app:sleepDurationFormatted="@{sleep}"/>
+
+        <TextView
+            android:id="@+id/quality_string"
+            android:layout_width="0dp"
+            android:layout_height="20dp"
+            android:layout_marginTop="8dp"
+            app:layout_constraintEnd_toEndOf="@+id/sleep_length"
+            app:layout_constraintHorizontal_bias="0.0"
+            app:layout_constraintStart_toStartOf="@+id/sleep_length"
+            app:layout_constraintTop_toBottomOf="@+id/sleep_length"
+            tools:text="Excellent!!!"
+            app:sleepQualityString="@{sleep}"/>
+    </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

RecyclerViewClickHandler/app/src/main/res/layout/text_item_view.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+
+<TextView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:textSize="24sp"
+    android:paddingStart="16dp"
+    android:paddingEnd="16dp"
+    android:layout_width="match_parent" android:layout_height="wrap_content" />

RecyclerViewClickHandler/app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_sleep_tracker_background" />
+    <foreground android:drawable="@drawable/ic_launcher_sleep_tracker_foreground" />
+</adaptive-icon>

RecyclerViewClickHandler/app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_sleep_tracker_background" />
+    <foreground android:drawable="@drawable/ic_launcher_sleep_tracker_foreground" />
+</adaptive-icon>

RecyclerViewClickHandler/app/src/main/res/mipmap-anydpi-v26/ic_launcher_sleep_tracker.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_sleep_tracker_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_sleep_tracker_foreground"/>
+</adaptive-icon>

RecyclerViewClickHandler/app/src/main/res/mipmap-anydpi-v26/ic_launcher_sleep_tracker_round.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_sleep_tracker_background"/>
+    <foreground android:drawable="@drawable/ic_launcher_sleep_tracker_foreground"/>
+</adaptive-icon>

RecyclerViewClickHandler/app/src/main/res/navigation/navigation.xml

@@ -0,0 +1,75 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<!-- Note that the animations may show red in Android Studio;
+     however, they are present and working perfectly fine. -->
+
+<navigation xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/navigation"
+    app:startDestination="@id/sleep_tracker_fragment">
+
+    <fragment
+        android:id="@+id/sleep_tracker_fragment"
+        android:name="com.example.android.trackmysleepquality.sleeptracker.SleepTrackerFragment"
+        android:label="@string/sleep_tracker_fragment"
+        tools:layout="@layout/fragment_sleep_tracker">
+        <action
+            android:id="@+id/action_sleepTrackerFragment_to_sleepQualityFragment"
+            app:destination="@id/sleep_quality_fragment"
+            app:enterAnim="@anim/slide_in_right"
+            app:popEnterAnim="@anim/slide_in_right" />
+        <action
+            android:id="@+id/action_sleep_tracker_fragment_to_sleepDetailFragment"
+            app:destination="@id/sleep_detail_fragment"
+            app:enterAnim="@anim/slide_in_right"
+            app:popEnterAnim="@anim/slide_in_right" />
+    </fragment>
+
+    <fragment
+        android:id="@+id/sleep_quality_fragment"
+        android:name="com.example.android.trackmysleepquality.sleepquality.SleepQualityFragment"
+        android:label="@string/sleep_quality_fragment"
+        tools:layout="@layout/fragment_sleep_quality">
+        <argument
+            android:name="sleepNightKey"
+            app:argType="long" />
+        <action
+            android:id="@+id/action_sleepQualityFragment_to_sleepTrackerFragment"
+            app:destination="@id/sleep_tracker_fragment"
+            app:launchSingleTop="false"
+            app:popUpTo="@+id/sleep_tracker_fragment"
+            app:popUpToInclusive="true" />
+    </fragment>
+
+    <fragment
+        android:id="@+id/sleep_detail_fragment"
+        android:name="com.example.android.trackmysleepquality.sleepdetail.SleepDetailFragment"
+        android:label="fragment_sleep_detail"
+        tools:layout="@layout/fragment_sleep_detail" >
+        <argument
+            android:name="sleepNightKey"
+            app:argType="long" />
+        <action
+            android:id="@+id/action_sleepDetailFragment_to_sleep_tracker_fragment"
+            app:destination="@id/sleep_tracker_fragment"
+            app:launchSingleTop="false"
+            app:popUpTo="@+id/sleep_tracker_fragment"
+            app:popUpToInclusive="true" />
+    </fragment>
+
+</navigation>

RecyclerViewClickHandler/app/src/main/res/values/colors.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+
+    <color name="colorPrimary">#6ab343</color>
+    <color name="colorPrimaryDark">#388310</color>
+    <color name="colorAccent">#6ab343</color>
+
+    <color name="green_color">#388310</color>
+    <color name="white_text_color">#f0f0f0</color>
+
+</resources>

RecyclerViewClickHandler/app/src/main/res/values/dimens.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <dimen name="margin">16dp</dimen>
+    <dimen name="icon_size">64dp</dimen>
+    <dimen name="title_text_size">20sp</dimen>
+    <dimen name="triple_margin">48dp</dimen>
+</resources>

RecyclerViewClickHandler/app/src/main/res/values/font_certs.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <array name="com_google_android_gms_fonts_certs">
+        <item>@array/com_google_android_gms_fonts_certs_dev</item>
+        <item>@array/com_google_android_gms_fonts_certs_prod</item>
+    </array>
+    <string-array name="com_google_android_gms_fonts_certs_dev">
+        <item>
+            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
+        </item>
+    </string-array>
+    <string-array name="com_google_android_gms_fonts_certs_prod">
+        <item>
+            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
+        </item>
+    </string-array>
+</resources>

RecyclerViewClickHandler/app/src/main/res/values/preloaded_fonts.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <array name="preloaded_fonts" translatable="false">
+        <item>@font/roboto</item>
+    </array>
+</resources>

RecyclerViewClickHandler/app/src/main/res/values/strings.xml

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+
+    <!-- App title and fragment titles -->
+    <string name="app_name">Track My Sleep Quality</string>
+    <string name="sleep_tracker_fragment">SleepTrackerFragment</string>
+    <string name="sleep_quality_fragment">SleepQualityFragment</string>
+
+    <!-- Button labels -->
+    <string name="start">Start</string>
+    <string name="stop">Stop</string>
+    <string name="clear">Clear</string>
+
+    <!-- contentDescription strings for quality icons -->
+    <string name="quality_0">Sleep Quality 0</string>
+    <string name="quality_1">Sleep Quality 1</string>
+    <string name="quality_2">Sleep Quality 2</string>
+    <string name="quality_3">Sleep Quality 3</string>
+    <string name="quality_4">Sleep Quality 4</string>
+    <string name="quality_5">Sleep Quality 5</string>
+
+    <!-- Output to TextView styled with a little HTML -->
+    <string name="title"><![CDATA[<h3>HERE IS YOUR SLEEP DATA</h3>]]></string>
+    <string name="start_time"><![CDATA[<b>Start:</b>]]></string>
+    <string name="end_time"><![CDATA[<b>End:</b>]]></string>
+    <string name="quality"><![CDATA[<b>Quality:</b>]]></string>
+    <string name="hours_slept"><![CDATA[<b>Hours:Minutes:Seconds</b>]]></string>
+
+    <!-- Sleep quality strings -->
+    <string name="how_was_hour_sleep">How was your sleep?</string>
+    <string name="zero_very_bad">Very bad</string>
+    <string name="one_poor">Poor</string>
+    <string name="two_soso">So-so</string>
+    <string name="three_ok">OK</string>
+    <string name="four_pretty_good">Pretty good</string>
+    <string name="five_excellent">Excellent!</string>
+
+    <!-- Toast to play after Clear button has been pressed -->
+    <string name="cleared_message">All your data is gone forever.</string>
+
+    <string name="header_text">Sleep Results</string>
+    <string name="close">Close</string>
+    <string name="minutes_length">%d minutes on %s</string>
+    <string name="hours_length">%d hours on %s</string>
+    <string name="seconds_length">%d seconds on %s</string>
+</resources>

RecyclerViewClickHandler/app/src/main/res/values/styles.xml

@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+
+    <!-- Base application theme. -->
+    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
+        <item name="colorPrimary">@color/colorPrimary</item>
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+    </style>
+
+    <!-- Basic styling for the buttons. -->
+    <style name="SleepButtons" parent="Widget.AppCompat.Button.Colored">
+        <item name="android:textColor">@color/white_text_color</item>
+        <item name="colorAccent">@color/green_color</item>
+        <item name="colorControlHighlight">@color/green_color</item>
+        <item name="android:textStyle">bold</item>
+    </style>
+
+</resources>

RecyclerViewClickHandler/build.gradle

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2018, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+buildscript {
+
+    ext {
+        kotlin_version = '1.3.10'
+        archLifecycleVersion = '1.1.1'
+        room_version = '2.0.0'
+        coroutine_version = '1.0.0'
+        gradleVersion = '3.4.0'
+        navigationVersion = '1.0.0-alpha07'
+        dataBindingCompilerVersion = gradleVersion // Always need to be the same.
+    }
+
+    repositories {
+        google()
+        jcenter()
+    }
+
+    dependencies {
+        classpath "com.android.tools.build:gradle:$gradleVersion"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+        classpath "android.arch.navigation:navigation-safe-args-gradle-plugin:$navigationVersion"
+
+        // NOTE: Do not place your application dependencies here; they belong
+        // in the individual module build.gradle files
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        jcenter()
+    }
+}
+
+task clean(type: Delete) {
+    delete rootProject.buildDir
+}

RecyclerViewClickHandler/gradle.properties

@@ -0,0 +1,15 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx1536m
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+android.useAndroidX=true
+android.enableJetifier=true

RecyclerViewClickHandler/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Tue May 14 17:22:57 PDT 2019
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-all.zip

RecyclerViewClickHandler/gradlew

@@ -0,0 +1,172 @@
+#!/usr/bin/env sh
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+# by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
+  cd "$(dirname "$0")"
+fi
+
+exec "$JAVACMD" "$@"

RecyclerViewClickHandler/gradlew.bat

@@ -0,0 +1,84 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

RecyclerViewClickHandler/settings.gradle

@@ -0,0 +1 @@
+include ':app'

RecyclerViewDiffUtilDataBinding/README.md

@@ -0,0 +1,55 @@
+TrackMySleepQuality with RecyclerView - Solution Code for 7.2
+============================================================
+
+Solution code for Android Kotlin Fundamentals Codelab 7.2 DiffUtil and data binding with RecyclerView
+
+Introduction
+------------
+
+TrackMySleepQuality is an app for recording sleep data for each night.
+You can record a start and stop time, assign a quality rating, and clear the database.
+
+Learn techniques that make RecyclerView more efficient for large lists.
+You will also learn techniques to make your code easier to maintain and extend for complex
+lists and grids in your Android Kotlin apps.
+
+
+Pre-requisites
+--------------
+
+You should be familiar with:
+
+* Building a basic user interface (UI) using an activity, fragments, and views.
+* Navigating between fragments, and using safeArgs to pass data between fragments.
+* Using view models, view model factories, transformations, and LiveData and their observers.
+* Creating a Room database, creating a DAO, and defining entities.
+* Using coroutines for database tasks and other long-running tasks.
+* How to implement a basic RecyclerView with an Adapter, ViewHolder, and item layout.
+
+
+
+Getting Started
+---------------
+
+1. Download and run the app.
+
+License
+-------
+
+Copyright 2019 Google, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you under the Apache License, Version 2.0 (the "License"); you may not
+use this file except in compliance with the License.  You may obtain a copy of
+the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+License for the specific language governing permissions and limitations under
+the License.
+

RecyclerViewDiffUtilDataBinding/app/.gitignore

@@ -0,0 +1 @@
+/build

RecyclerViewDiffUtilDataBinding/app/build.gradle

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+apply plugin: 'kotlin-kapt'
+apply plugin: 'androidx.navigation.safeargs'
+
+android {
+    compileSdkVersion 28
+    defaultConfig {
+        applicationId "com.example.android.trackmysleepqualityrecyclerview"
+        minSdkVersion 19
+        targetSdkVersion 28
+        versionCode 1
+        versionName "1.0"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        vectorDrawables.useSupportLibrary = true
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+
+    // Enables data binding.
+    dataBinding {
+        enabled = true
+    }
+
+}
+
+dependencies {
+
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+
+    // Support libraries
+    implementation "androidx.appcompat:appcompat:1.0.0"
+    implementation "androidx.fragment:fragment:1.0.0"
+    implementation "androidx.constraintlayout:constraintlayout:2.0.0-alpha2"
+
+    // Android KTX
+    implementation 'androidx.core:core-ktx:1.0.1'
+
+    // Room and Lifecycle dependencies
+    implementation "androidx.room:room-runtime:$room_version"
+    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
+    kapt "androidx.room:room-compiler:$room_version"
+    implementation "androidx.lifecycle:lifecycle-extensions:2.0.0"
+
+    // Coroutines
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutine_version"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutine_version"
+
+    // Navigation
+    implementation "android.arch.navigation:navigation-fragment-ktx:$navigationVersion"
+    implementation "android.arch.navigation:navigation-ui-ktx:$navigationVersion"
+
+    // Testing
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test:runner:1.1.0-alpha4'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha4'
+}
+

RecyclerViewDiffUtilDataBinding/app/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

RecyclerViewDiffUtilDataBinding/app/src/main/AndroidManifest.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.android.trackmysleepquality">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher_sleep_tracker"
+        android:label="@string/app_name"
+        android:roundIcon="@mipmap/ic_launcher_sleep_tracker_round"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <meta-data
+            android:name="preloaded_fonts"
+            android:resource="@array/preloaded_fonts" />
+    </application>
+
+</manifest>

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/MainActivity.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        setContentView(R.layout.activity_main)
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/Util.kt

@@ -0,0 +1,156 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality
+
+import android.annotation.SuppressLint
+import android.content.res.Resources
+import android.os.Build
+import android.text.Html
+import android.text.Spanned
+import android.view.View
+import android.widget.TextView
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.trackmysleepquality.database.SleepNight
+import java.text.SimpleDateFormat
+import java.util.*
+import java.util.concurrent.TimeUnit
+
+/**
+ * These functions create a formatted string that can be set in a TextView.
+ */
+
+private val ONE_MINUTE_MILLIS = TimeUnit.MILLISECONDS.convert(1, TimeUnit.MINUTES)
+private val ONE_HOUR_MILLIS = TimeUnit.MILLISECONDS.convert(1, TimeUnit.HOURS)
+
+/**
+ * Convert a duration to a formatted string for display.
+ *
+ * Examples:
+ *
+ * 6 seconds on Wednesday
+ * 2 minutes on Monday
+ * 40 hours on Thursday
+ *
+ * @param startTimeMilli the start of the interval
+ * @param endTimeMilli the end of the interval
+ * @param res resources used to load formatted strings
+ */
+fun convertDurationToFormatted(startTimeMilli: Long, endTimeMilli: Long, res: Resources): String {
+    val durationMilli = endTimeMilli - startTimeMilli
+    val weekdayString = SimpleDateFormat("EEEE", Locale.getDefault()).format(startTimeMilli)
+    return when {
+        durationMilli < ONE_MINUTE_MILLIS -> {
+            val seconds = TimeUnit.SECONDS.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.seconds_length, seconds, weekdayString)
+        }
+        durationMilli < ONE_HOUR_MILLIS -> {
+            val minutes = TimeUnit.MINUTES.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.minutes_length, minutes, weekdayString)
+        }
+        else -> {
+            val hours = TimeUnit.HOURS.convert(durationMilli, TimeUnit.MILLISECONDS)
+            res.getString(R.string.hours_length, hours, weekdayString)
+        }
+    }
+}
+
+/**
+ * Returns a string representing the numeric quality rating.
+ */
+fun convertNumericQualityToString(quality: Int, resources: Resources): String {
+    var qualityString = resources.getString(R.string.three_ok)
+    when (quality) {
+        -1 -> qualityString = "--"
+        0 -> qualityString = resources.getString(R.string.zero_very_bad)
+        1 -> qualityString = resources.getString(R.string.one_poor)
+        2 -> qualityString = resources.getString(R.string.two_soso)
+        4 -> qualityString = resources.getString(R.string.four_pretty_good)
+        5 -> qualityString = resources.getString(R.string.five_excellent)
+    }
+    return qualityString
+}
+
+
+/**
+ * Take the Long milliseconds returned by the system and stored in Room,
+ * and convert it to a nicely formatted string for display.
+ *
+ * EEEE - Display the long letter version of the weekday
+ * MMM - Display the letter abbreviation of the nmotny
+ * dd-yyyy - day in month and full year numerically
+ * HH:mm - Hours and minutes in 24hr format
+ */
+@SuppressLint("SimpleDateFormat")
+fun convertLongToDateString(systemTime: Long): String {
+    return SimpleDateFormat("EEEE MMM-dd-yyyy' Time: 'HH:mm")
+            .format(systemTime).toString()
+}
+
+/**
+ * Takes a list of SleepNights and converts and formats it into one string for display.
+ *
+ * For display in a TextView, we have to supply one string, and styles are per TextView, not
+ * applicable per word. So, we build a formatted string using HTML. This is handy, but we will
+ * learn a better way of displaying this data in a future lesson.
+ *
+ * @param   nights - List of all SleepNights in the database.
+ * @param   resources - Resources object for all the resources defined for our app.
+ *
+ * @return  Spanned - An interface for text that has formatting attached to it.
+ *           See: https://developer.android.com/reference/android/text/Spanned
+ */
+fun formatNights(nights: List<SleepNight>, resources: Resources): Spanned {
+    val sb = StringBuilder()
+    sb.apply {
+        append(resources.getString(R.string.title))
+        nights.forEach {
+            append("<br>")
+            append(resources.getString(R.string.start_time))
+            append("\t${convertLongToDateString(it.startTimeMilli)}<br>")
+            if (it.endTimeMilli != it.startTimeMilli) {
+                append(resources.getString(R.string.end_time))
+                append("\t${convertLongToDateString(it.endTimeMilli)}<br>")
+                append(resources.getString(R.string.quality))
+                append("\t${convertNumericQualityToString(it.sleepQuality, resources)}<br>")
+                append(resources.getString(R.string.hours_slept))
+                // Hours
+                append("\t ${it.endTimeMilli.minus(it.startTimeMilli) / 1000 / 60 / 60}:")
+                // Minutes
+                append("${it.endTimeMilli.minus(it.startTimeMilli) / 1000 / 60}:")
+                // Seconds
+                append("${it.endTimeMilli.minus(it.startTimeMilli) / 1000}<br><br>")
+            }
+        }
+    }
+    // fromHtml is deprecated for target API without a flag, but since our minSDK is 19, we
+    // can't use the newer version, which requires minSDK of 24
+    //https://developer.android.com/reference/android/text/Html#fromHtml(java.lang.String,%20int)
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+        return Html.fromHtml(sb.toString(), Html.FROM_HTML_MODE_LEGACY)
+    } else {
+        @Suppress("DEPRECATION")
+        return Html.fromHtml(sb.toString())
+    }
+}
+
+/**
+ * ViewHolder that holds a single [TextView].
+ *
+ * A ViewHolder holds a view for the [RecyclerView] as well as providing additional information
+ * to the RecyclerView such as where on the screen it was last drawn during scrolling.
+ */
+class TextItemViewHolder(val textView: TextView): RecyclerView.ViewHolder(textView)

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/database/SleepDatabase.kt

@@ -0,0 +1,107 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import android.content.Context
+import androidx.room.Database
+import androidx.room.Room
+import androidx.room.RoomDatabase
+
+/**
+ * A database that stores SleepNight information.
+ * And a global method to get access to the database.
+ *
+ * This pattern is pretty much the same for any database,
+ * so you can reuse it.
+ */
+@Database(entities = [SleepNight::class], version = 1, exportSchema = false)
+abstract class SleepDatabase : RoomDatabase() {
+
+    /**
+     * Connects the database to the DAO.
+     */
+    abstract val sleepDatabaseDao: SleepDatabaseDao
+
+    /**
+     * Define a companion object, this allows us to add functions on the SleepDatabase class.
+     *
+     * For example, clients can call `SleepDatabase.getInstance(context)` to instantiate
+     * a new SleepDatabase.
+     */
+    companion object {
+        /**
+         * INSTANCE will keep a reference to any database returned via getInstance.
+         *
+         * This will help us avoid repeatedly initializing the database, which is expensive.
+         *
+         *  The value of a volatile variable will never be cached, and all writes and
+         *  reads will be done to and from the main memory. It means that changes made by one
+         *  thread to shared data are visible to other threads.
+         */
+        @Volatile
+        private var INSTANCE: SleepDatabase? = null
+
+        /**
+         * Helper function to get the database.
+         *
+         * If a database has already been retrieved, the previous database will be returned.
+         * Otherwise, create a new database.
+         *
+         * This function is threadsafe, and callers should cache the result for multiple database
+         * calls to avoid overhead.
+         *
+         * This is an example of a simple Singleton pattern that takes another Singleton as an
+         * argument in Kotlin.
+         *
+         * To learn more about Singleton read the wikipedia article:
+         * https://en.wikipedia.org/wiki/Singleton_pattern
+         *
+         * @param context The application context Singleton, used to get access to the filesystem.
+         */
+        fun getInstance(context: Context): SleepDatabase {
+            // Multiple threads can ask for the database at the same time, ensure we only initialize
+            // it once by using synchronized. Only one thread may enter a synchronized block at a
+            // time.
+            synchronized(this) {
+
+                // Copy the current value of INSTANCE to a local variable so Kotlin can smart cast.
+                // Smart cast is only available to local variables.
+                var instance = INSTANCE
+
+                // If instance is `null` make a new database instance.
+                if (instance == null) {
+                    instance = Room.databaseBuilder(
+                            context.applicationContext,
+                            SleepDatabase::class.java,
+                            "sleep_history_database"
+                    )
+                            // Wipes and rebuilds instead of migrating if no Migration object.
+                            // Migration is not part of this lesson. You can learn more about
+                            // migration with Room in this blog post:
+                            // https://medium.com/androiddevelopers/understanding-migrations-with-room-f01e04b07929
+                            .fallbackToDestructiveMigration()
+                            .build()
+                    // Assign INSTANCE to the newly created database.
+                    INSTANCE = instance
+                }
+
+                // Return instance; smart cast to be non-null.
+                return instance
+            }
+        }
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/database/SleepDatabaseDao.kt

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import androidx.lifecycle.LiveData
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Update
+
+
+/**
+ * Defines methods for using the SleepNight class with Room.
+ */
+@Dao
+interface SleepDatabaseDao {
+
+    @Insert
+    fun insert(night: SleepNight)
+
+    /**
+     * When updating a row with a value already set in a column,
+     * replaces the old value with the new one.
+     *
+     * @param night new value to write
+     */
+    @Update
+    fun update(night: SleepNight)
+
+    /**
+     * Selects and returns the row that matches the supplied start time, which is our key.
+     *
+     * @param key startTimeMilli to match
+     */
+    @Query("SELECT * from daily_sleep_quality_table WHERE nightId = :key")
+    fun get(key: Long): SleepNight
+
+    /**
+     * Deletes all values from the table.
+     *
+     * This does not delete the table, only its contents.
+     */
+    @Query("DELETE FROM daily_sleep_quality_table")
+    fun clear()
+
+    /**
+     * Selects and returns all rows in the table,
+     *
+     * sorted by start time in descending order.
+     */
+    @Query("SELECT * FROM daily_sleep_quality_table ORDER BY nightId DESC")
+    fun getAllNights(): LiveData<List<SleepNight>>
+
+    /**
+     * Selects and returns the latest night.
+     */
+    @Query("SELECT * FROM daily_sleep_quality_table ORDER BY nightId DESC LIMIT 1")
+    fun getTonight(): SleepNight?
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/database/SleepNight.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.database
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+
+/**
+ * Represents one night's sleep through start, end times, and the sleep quality.
+ */
+@Entity(tableName = "daily_sleep_quality_table")
+data class SleepNight(
+        @PrimaryKey(autoGenerate = true)
+        var nightId: Long = 0L,
+
+        @ColumnInfo(name = "start_time_milli")
+        val startTimeMilli: Long = System.currentTimeMillis(),
+
+        @ColumnInfo(name = "end_time_milli")
+        var endTimeMilli: Long = startTimeMilli,
+
+        @ColumnInfo(name = "quality_rating")
+        var sleepQuality: Int = -1)

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityFragment.kt

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
+import androidx.navigation.fragment.findNavController
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.database.SleepDatabase
+import com.example.android.trackmysleepquality.databinding.FragmentSleepQualityBinding
+
+/**
+ * Fragment that displays a list of clickable icons,
+ * each representing a sleep quality rating.
+ * Once the user taps an icon, the quality is set in the current sleepNight
+ * and the database is updated.
+ */
+class SleepQualityFragment : Fragment() {
+
+    /**
+     * Called when the Fragment is ready to display content to the screen.
+     *
+     * This function uses DataBindingUtil to inflate R.layout.fragment_sleep_quality.
+     *
+     * It is also responsible for passing the [SleepQualityViewModel] to the
+     * [FragmentSleepQualityBinding] generated by DataBinding. This will allow DataBinding
+     * to use the [LiveData] on our ViewModel.
+     */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+
+        // Get a reference to the binding object and inflate the fragment views.
+        val binding: FragmentSleepQualityBinding = DataBindingUtil.inflate(
+                inflater, R.layout.fragment_sleep_quality, container, false)
+
+        val application = requireNotNull(this.activity).application
+        val arguments = SleepQualityFragmentArgs.fromBundle(arguments)
+
+        // Create an instance of the ViewModel Factory.
+        val dataSource = SleepDatabase.getInstance(application).sleepDatabaseDao
+        val viewModelFactory = SleepQualityViewModelFactory(arguments.sleepNightKey, dataSource)
+
+        // Get a reference to the ViewModel associated with this fragment.
+        val sleepQualityViewModel =
+                ViewModelProviders.of(
+                        this, viewModelFactory).get(SleepQualityViewModel::class.java)
+
+        // To use the View Model with data binding, you have to explicitly
+        // give the binding object a reference to it.
+        binding.sleepQualityViewModel = sleepQualityViewModel
+
+        // Add an Observer to the state variable for Navigating when a Quality icon is tapped.
+        sleepQualityViewModel.navigateToSleepTracker.observe(this, Observer {
+            if (it == true) { // Observed state is true.
+                this.findNavController().navigate(
+                        SleepQualityFragmentDirections.actionSleepQualityFragmentToSleepTrackerFragment())
+                // Reset state to make sure we only navigate once, even if the device
+                // has a configuration change.
+                sleepQualityViewModel.doneNavigating()
+            }
+        })
+
+        return binding.root
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityViewModel.kt

@@ -0,0 +1,113 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * ViewModel for SleepQualityFragment.
+ *
+ * @param sleepNightKey The key of the current night we are working on.
+ */
+class SleepQualityViewModel(
+        private val sleepNightKey: Long = 0L,
+        dataSource: SleepDatabaseDao) : ViewModel() {
+
+    /**
+     * Hold a reference to SleepDatabase via its SleepDatabaseDao.
+     */
+    val database = dataSource
+
+    /** Coroutine setup variables */
+
+    /**
+     * viewModelJob allows us to cancel all coroutines started by this ViewModel.
+     */
+    private val viewModelJob = Job()
+
+    /**
+     * A [CoroutineScope] keeps track of all coroutines started by this ViewModel.
+     *
+     * Because we pass it [viewModelJob], any coroutine started in this scope can be cancelled
+     * by calling `viewModelJob.cancel()`
+     *
+     * By default, all coroutines started in uiScope will launch in [Dispatchers.Main] which is
+     * the main thread on Android. This is a sensible default because most coroutines started by
+     * a [ViewModel] update the UI after performing some processing.
+     */
+    private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
+
+    /**
+     * Variable that tells the fragment whether it should navigate to [SleepTrackerFragment].
+     *
+     * This is `private` because we don't want to expose the ability to set [MutableLiveData] to
+     * the [Fragment]
+     */
+    private val _navigateToSleepTracker = MutableLiveData<Boolean?>()
+
+    /**
+     * When true immediately navigate back to the [SleepTrackerFragment]
+     */
+    val navigateToSleepTracker: LiveData<Boolean?>
+        get() = _navigateToSleepTracker
+
+    /**
+     * Cancels all coroutines when the ViewModel is cleared, to cleanup any pending work.
+     *
+     * onCleared() gets called when the ViewModel is destroyed.
+     */
+    override fun onCleared() {
+        super.onCleared()
+        viewModelJob.cancel()
+    }
+
+
+    /**
+     * Call this immediately after navigating to [SleepTrackerFragment]
+     */
+    fun doneNavigating() {
+        _navigateToSleepTracker.value = null
+    }
+
+    /**
+     * Sets the sleep quality and updates the database.
+     *
+     * Then navigates back to the SleepTrackerFragment.
+     */
+    fun onSetSleepQuality(quality: Int) {
+        uiScope.launch {
+            // IO is a thread pool for running operations that access the disk, such as
+            // our Room database.
+            withContext(Dispatchers.IO) {
+                val tonight = database.get(sleepNightKey)
+                tonight.sleepQuality = quality
+                database.update(tonight)
+            }
+
+            // Setting this state variable to true will alert the observer and trigger navigation.
+            _navigateToSleepTracker.value = true
+        }
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleepquality/SleepQualityViewModelFactory.kt

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleepquality
+
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+
+/**
+ * This is pretty much boiler plate code for a ViewModel Factory.
+ *
+ * Provides the key for the night and the SleepDatabaseDao to the ViewModel.
+ */
+class SleepQualityViewModelFactory(
+        private val sleepNightKey: Long,
+        private val dataSource: SleepDatabaseDao) : ViewModelProvider.Factory {
+    @Suppress("unchecked_cast")
+    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+        if (modelClass.isAssignableFrom(SleepQualityViewModel::class.java)) {
+            return SleepQualityViewModel(sleepNightKey, dataSource) as T
+        }
+        throw IllegalArgumentException("Unknown ViewModel class")
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/BindingUtils.kt

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.widget.ImageView
+import android.widget.TextView
+import androidx.databinding.BindingAdapter
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.convertDurationToFormatted
+import com.example.android.trackmysleepquality.convertNumericQualityToString
+import com.example.android.trackmysleepquality.database.SleepNight
+
+
+@BindingAdapter("sleepDurationFormatted")
+fun TextView.setSleepDurationFormatted(item: SleepNight) {
+    text = convertDurationToFormatted(item.startTimeMilli, item.endTimeMilli, context.resources)
+}
+
+
+@BindingAdapter("sleepQualityString")
+fun TextView.setSleepQualityString(item: SleepNight) {
+    text = convertNumericQualityToString(item.sleepQuality, context.resources)
+}
+
+
+@BindingAdapter("sleepImage")
+fun ImageView.setSleepImage(item: SleepNight) {
+    setImageResource(when (item.sleepQuality) {
+        0 -> R.drawable.ic_sleep_0
+        1 -> R.drawable.ic_sleep_1
+        2 -> R.drawable.ic_sleep_2
+
+        3 -> R.drawable.ic_sleep_3
+
+        4 -> R.drawable.ic_sleep_4
+        5 -> R.drawable.ic_sleep_5
+        else -> R.drawable.ic_sleep_active
+    })
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepNightAdapter.kt

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.convertDurationToFormatted
+import com.example.android.trackmysleepquality.convertNumericQualityToString
+import com.example.android.trackmysleepquality.database.SleepNight
+import com.example.android.trackmysleepquality.databinding.ListItemSleepNightBinding
+
+class SleepNightAdapter : ListAdapter<SleepNight, SleepNightAdapter.ViewHolder>(SleepNightDiffCallback()) {
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        val item = getItem(position)
+        holder.bind(item)
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        return ViewHolder.from(parent)
+    }
+
+    class ViewHolder private constructor(val binding: ListItemSleepNightBinding) : RecyclerView.ViewHolder(binding.root){
+
+        fun bind(item: SleepNight) {
+            binding.sleep = item
+            binding.executePendingBindings()
+        }
+
+        companion object {
+            fun from(parent: ViewGroup): ViewHolder {
+                val layoutInflater = LayoutInflater.from(parent.context)
+                val binding = ListItemSleepNightBinding.inflate(layoutInflater, parent, false)
+                return ViewHolder(binding)
+            }
+        }
+    }
+}
+
+
+class SleepNightDiffCallback : DiffUtil.ItemCallback<SleepNight>() {
+
+    override fun areItemsTheSame(oldItem: SleepNight, newItem: SleepNight): Boolean {
+        return oldItem.nightId == newItem.nightId
+    }
+
+
+    override fun areContentsTheSame(oldItem: SleepNight, newItem: SleepNight): Boolean {
+        return oldItem == newItem
+    }
+
+
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerFragment.kt

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.lifecycle.ViewModelProviders
+import androidx.navigation.fragment.findNavController
+import com.example.android.trackmysleepquality.R
+import com.example.android.trackmysleepquality.database.SleepDatabase
+import com.example.android.trackmysleepquality.databinding.FragmentSleepTrackerBinding
+import com.google.android.material.snackbar.Snackbar
+
+/**
+ * A fragment with buttons to record start and end times for sleep, which are saved in
+ * a database. Cumulative data is displayed in a simple scrollable TextView.
+ * (Because we have not learned about RecyclerView yet.)
+ * The Clear button will clear all data from the database.
+ */
+class SleepTrackerFragment : Fragment() {
+
+    /**
+     * Called when the Fragment is ready to display content to the screen.
+     *
+     * This function uses DataBindingUtil to inflate R.layout.fragment_sleep_quality.
+     *
+     * It is also responsible for passing the [SleepTrackerViewModel] to the
+     * [FragmentSleepTrackerBinding] generated by DataBinding. This will allow DataBinding
+     * to use the [LiveData] on our ViewModel.
+     */
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
+                              savedInstanceState: Bundle?): View? {
+
+        // Get a reference to the binding object and inflate the fragment views.
+        val binding: FragmentSleepTrackerBinding = DataBindingUtil.inflate(
+                inflater, R.layout.fragment_sleep_tracker, container, false)
+
+        val application = requireNotNull(this.activity).application
+
+        // Create an instance of the ViewModel Factory.
+        val dataSource = SleepDatabase.getInstance(application).sleepDatabaseDao
+        val viewModelFactory = SleepTrackerViewModelFactory(dataSource, application)
+
+        // Get a reference to the ViewModel associated with this fragment.
+        val sleepTrackerViewModel =
+                ViewModelProviders.of(
+                        this, viewModelFactory).get(SleepTrackerViewModel::class.java)
+
+        // To use the View Model with data binding, you have to explicitly
+        // give the binding object a reference to it.
+        binding.sleepTrackerViewModel = sleepTrackerViewModel
+
+        val adapter = SleepNightAdapter()
+        binding.sleepList.adapter = adapter
+
+        sleepTrackerViewModel.nights.observe(viewLifecycleOwner, Observer {
+            it?.let {
+                adapter.submitList(it)
+            }
+        })
+
+        // Specify the current activity as the lifecycle owner of the binding.
+        // This is necessary so that the binding can observe LiveData updates.
+        binding.setLifecycleOwner(this)
+
+        // Add an Observer on the state variable for showing a Snackbar message
+        // when the CLEAR button is pressed.
+        sleepTrackerViewModel.showSnackBarEvent.observe(this, Observer {
+            if (it == true) { // Observed state is true.
+                Snackbar.make(
+                        activity!!.findViewById(android.R.id.content),
+                        getString(R.string.cleared_message),
+                        Snackbar.LENGTH_SHORT // How long to display the message.
+                ).show()
+                // Reset state to make sure the toast is only shown once, even if the device
+                // has a configuration change.
+                sleepTrackerViewModel.doneShowingSnackbar()
+            }
+        })
+
+        // Add an Observer on the state variable for Navigating when STOP button is pressed.
+        sleepTrackerViewModel.navigateToSleepQuality.observe(this, Observer { night ->
+            night?.let {
+                // We need to get the navController from this, because button is not ready, and it
+                // just has to be a view. For some reason, this only matters if we hit stop again
+                // after using the back button, not if we hit stop and choose a quality.
+                // Also, in the Navigation Editor, for Quality -> Tracker, check "Inclusive" for
+                // popping the stack to get the correct behavior if we press stop multiple times
+                // followed by back.
+                // Also: https://stackoverflow.com/questions/28929637/difference-and-uses-of-oncreate-oncreateview-and-onactivitycreated-in-fra
+                this.findNavController().navigate(
+                        SleepTrackerFragmentDirections
+                                .actionSleepTrackerFragmentToSleepQualityFragment(night.nightId))
+                // Reset state to make sure we only navigate once, even if the device
+                // has a configuration change.
+                sleepTrackerViewModel.doneNavigating()
+            }
+        })
+        return binding.root
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerViewModel.kt

@@ -0,0 +1,249 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+import android.app.Application
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.Transformations
+import androidx.lifecycle.ViewModel
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+import com.example.android.trackmysleepquality.database.SleepNight
+import com.example.android.trackmysleepquality.formatNights
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * ViewModel for SleepTrackerFragment.
+ */
+class SleepTrackerViewModel(
+        dataSource: SleepDatabaseDao,
+        application: Application) : ViewModel() {
+
+    /**
+     * Hold a reference to SleepDatabase via SleepDatabaseDao.
+     */
+    val database = dataSource
+
+    /** Coroutine variables */
+
+    /**
+     * viewModelJob allows us to cancel all coroutines started by this ViewModel.
+     */
+    private var viewModelJob = Job()
+
+    /**
+     * A [CoroutineScope] keeps track of all coroutines started by this ViewModel.
+     *
+     * Because we pass it [viewModelJob], any coroutine started in this uiScope can be cancelled
+     * by calling `viewModelJob.cancel()`
+     *
+     * By default, all coroutines started in uiScope will launch in [Dispatchers.Main] which is
+     * the main thread on Android. This is a sensible default because most coroutines started by
+     * a [ViewModel] update the UI after performing some processing.
+     */
+    private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
+
+    private var tonight = MutableLiveData<SleepNight?>()
+
+    val nights = database.getAllNights()
+
+    /**
+     * Converted nights to Spanned for displaying.
+     */
+    val nightsString = Transformations.map(nights) { nights ->
+        formatNights(nights, application.resources)
+    }
+
+    /**
+     * If tonight has not been set, then the START button should be visible.
+     */
+    val startButtonVisible = Transformations.map(tonight) {
+        null == it
+    }
+
+    /**
+     * If tonight has been set, then the STOP button should be visible.
+     */
+    val stopButtonVisible = Transformations.map(tonight) {
+        null != it
+    }
+
+    /**
+     * If there are any nights in the database, show the CLEAR button.
+     */
+    val clearButtonVisible = Transformations.map(nights) {
+        it?.isNotEmpty()
+    }
+
+
+    /**
+     * Request a toast by setting this value to true.
+     *
+     * This is private because we don't want to expose setting this value to the Fragment.
+     */
+    private var _showSnackbarEvent = MutableLiveData<Boolean?>()
+
+    /**
+     * If this is true, immediately `show()` a toast and call `doneShowingSnackbar()`.
+     */
+    val showSnackBarEvent: LiveData<Boolean?>
+        get() = _showSnackbarEvent
+
+    /**
+     * Variable that tells the Fragment to navigate to a specific [SleepQualityFragment]
+     *
+     * This is private because we don't want to expose setting this value to the Fragment.
+     */
+    private val _navigateToSleepQuality = MutableLiveData<SleepNight>()
+
+    /**
+     * If this is non-null, immediately navigate to [SleepQualityFragment] and call [doneNavigating]
+     */
+    val navigateToSleepQuality: LiveData<SleepNight>
+        get() = _navigateToSleepQuality
+
+    /**
+     * Call this immediately after calling `show()` on a toast.
+     *
+     * It will clear the toast request, so if the user rotates their phone it won't show a duplicate
+     * toast.
+     */
+    fun doneShowingSnackbar() {
+        _showSnackbarEvent.value = null
+    }
+
+    /**
+     * Call this immediately after navigating to [SleepQualityFragment]
+     *
+     * It will clear the navigation request, so if the user rotates their phone it won't navigate
+     * twice.
+     */
+    fun doneNavigating() {
+        _navigateToSleepQuality.value = null
+    }
+
+    init {
+        initializeTonight()
+    }
+
+    private fun initializeTonight() {
+        uiScope.launch {
+            tonight.value = getTonightFromDatabase()
+        }
+    }
+
+    /**
+     *  Handling the case of the stopped app or forgotten recording,
+     *  the start and end times will be the same.j
+     *
+     *  If the start time and end time are not the same, then we do not have an unfinished
+     *  recording.
+     */
+    private suspend fun getTonightFromDatabase(): SleepNight? {
+        return withContext(Dispatchers.IO) {
+            var night = database.getTonight()
+            if (night?.endTimeMilli != night?.startTimeMilli) {
+                night = null
+            }
+            night
+        }
+    }
+
+    private suspend fun insert(night: SleepNight) {
+        withContext(Dispatchers.IO) {
+            database.insert(night)
+        }
+    }
+
+    private suspend fun update(night: SleepNight) {
+        withContext(Dispatchers.IO) {
+            database.update(night)
+        }
+    }
+
+    private suspend fun clear() {
+        withContext(Dispatchers.IO) {
+            database.clear()
+        }
+    }
+
+    /**
+     * Executes when the START button is clicked.
+     */
+    fun onStart() {
+        uiScope.launch {
+            // Create a new night, which captures the current time,
+            // and insert it into the database.
+            val newNight = SleepNight()
+
+            insert(newNight)
+
+            tonight.value = getTonightFromDatabase()
+        }
+    }
+
+    /**
+     * Executes when the STOP button is clicked.
+     */
+    fun onStop() {
+        uiScope.launch {
+            // In Kotlin, the return@label syntax is used for specifying which function among
+            // several nested ones this statement returns from.
+            // In this case, we are specifying to return from launch().
+            val oldNight = tonight.value ?: return@launch
+
+            // Update the night in the database to add the end time.
+            oldNight.endTimeMilli = System.currentTimeMillis()
+
+            update(oldNight)
+
+            // Set state to navigate to the SleepQualityFragment.
+            _navigateToSleepQuality.value = oldNight
+        }
+    }
+
+    /**
+     * Executes when the CLEAR button is clicked.
+     */
+    fun onClear() {
+        uiScope.launch {
+            // Clear the database table.
+            clear()
+
+            // And clear tonight since it's no longer in the database
+            tonight.value = null
+
+            // Show a snackbar message, because it's friendly.
+            _showSnackbarEvent.value = true
+        }
+    }
+
+    /**
+     * Called when the ViewModel is dismantled.
+     * At this point, we want to cancel all coroutines;
+     * otherwise we end up with processes that have nowhere to return to
+     * using memory and resources.
+     */
+    override fun onCleared() {
+        super.onCleared()
+        viewModelJob.cancel()
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/java/com/example/android/trackmysleepquality/sleeptracker/SleepTrackerViewModelFactory.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2019, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.trackmysleepquality.sleeptracker
+
+
+import android.app.Application
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import com.example.android.trackmysleepquality.database.SleepDatabaseDao
+
+/**
+ * This is pretty much boiler plate code for a ViewModel Factory.
+ *
+ * Provides the SleepDatabaseDao and context to the ViewModel.
+ */
+class SleepTrackerViewModelFactory(
+        private val dataSource: SleepDatabaseDao,
+        private val application: Application) : ViewModelProvider.Factory {
+    @Suppress("unchecked_cast")
+    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+        if (modelClass.isAssignableFrom(SleepTrackerViewModel::class.java)) {
+            return SleepTrackerViewModel(dataSource, application) as T
+        }
+        throw IllegalArgumentException("Unknown ViewModel class")
+    }
+}

RecyclerViewDiffUtilDataBinding/app/src/main/res/anim/slide_in_right.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <translate
+        android:duration="700"
+        android:fromXDelta="100%"
+        android:fromYDelta="0%"
+        android:toXDelta="0%"
+        android:toYDelta="0%" />
+</set>

RecyclerViewDiffUtilDataBinding/app/src/main/res/drawable/ic_launcher_sleep_tracker_background.xml

@@ -0,0 +1,55 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportWidth="512"
+        android:viewportHeight="512">
+  <path
+      android:pathData="M0,369.07h512v142.93h-512z"
+      android:fillColor="#e0e0e0"/>
+  <path
+      android:pathData="M228.55,271.42l15.7,-30.1L225,244.55l-1,-5.78 26.34,-4.41 1,6.22 -15.6,30.07L256,267.26l1,5.79 -27.42,4.59Z"
+      android:fillColor="#757575"/>
+  <path
+      android:pathData="M271.75,215.33l41.52,-29.2 -27.86,-9 2.68,-8.35 38,12.23 -2.89,9 -41.37,29.25 29.28,9.41L308.44,237l-39.58,-12.73Z"
+      android:fillColor="#bdbdbd"/>
+  <path
+      android:pathData="M350,187.18l39.94,-79.32L339.54,117l-2.75,-15.11 68.74,-12.52 3,16.23 -39.67,79.27 52.94,-9.64 2.75,15.1 -71.57,13Z"
+      android:fillColor="#e0e0e0"/>
+  <group>
+    <clip-path android:pathData="M584.94,-624.15h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M448.55,-187.1,709.34,73.69a8.72,8.72,0,0,0,12.32,0l325.45,-325.45a8.72,8.72,0,0,0,0,-12.32L778,-533.19a18.84,18.84,0,0,0,-26.65,0L442,-241.74l-2.36,5.16A44.05,44.05,0,0,0,448.55,-187.1Z"
+        android:fillColor="#43a047"/>
+    <path
+        android:pathData="M440.25,-208.98l275.52002,275.53l335.0,-335.0l-278.15002,-278.14996l-334.26,328.40997l1.8900146,9.210007z"
+        android:fillColor="#c0ca33"/>
+    <path
+        android:pathData="M544.72,-487.03h393.36v473.76h-393.36z"
+        android:fillColor="#e6ee9c"/>
+    <path
+        android:pathData="M548.74,-506.95H930.26a8.41,8.41,0,0,1,8.41,8.41V-37.68a8.41,8.41,0,0,1,-8.41,8.41H548.74a18.19,18.19,0,0,1,-18.19,-18.19V-488.75A18.19,18.19,0,0,1,548.74,-506.95Z"
+        android:fillColor="#6ab343"/>
+  </group>
+  <group>
+    <clip-path android:pathData="M0,-624.15h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M246.59,-272.23l39.17,-11.46a3.9,3.9,0,0,0,2.67,-4.84,3.9,3.9,0,0,0,-4.84,-2.63L244,-279.58a134.83,134.83,0,0,0,-30.74,-47.09,134.89,134.89,0,0,0,-47,-30.69l11.49,-39.52a3.86,3.86,0,0,0,-2.63,-4.83,3.85,3.85,0,0,0,-4.83,2.64l-11.42,39.16c-41.3,-13.2,-86.47,-4.85,-117.17,25.89l178.9,178.87c30.72,-30.71,39,-75.79,25.93,-117.08m-211,-54.15L-93.27,-197.48a29.94,29.94,0,0,0,0,42.38l14.43,14.44,-44,44a28.1,28.1,0,0,0,0,39.7,28.12,28.12,0,0,0,39.74,0l44,-44,26.81,26.8,-44,44a28.09,28.09,0,0,0,0,39.7,28.11,28.11,0,0,0,39.74,0l44,-44L41.91,-20A30,30,0,0,0,84.3,-20L213.16,-148.87Zm180.59,90.91L203.59,-248a1.7,1.7,0,0,1,0,-2.4l1.59,-1.6a1.71,1.71,0,0,1,2.41,0l12.58,12.59a1.7,1.7,0,0,1,0,2.4l-1.59,1.59A1.7,1.7,0,0,1,216.17,-235.47Zm-81.43,-81.42,-12.58,-12.59a1.7,1.7,0,0,1,0,-2.4l1.59,-1.59a1.7,1.7,0,0,1,2.41,0l12.58,12.58a1.68,1.68,0,0,1,0,2.4l-1.59,1.6A1.71,1.71,0,0,1,134.74,-316.89Zm-99.16,-9.49L-93.27,-197.48a29.94,29.94,0,0,0,0,42.38l14.43,14.44,-44,44a28.1,28.1,0,0,0,0,39.7,28.12,28.12,0,0,0,39.74,0l44,-44,26.81,26.8,-44,44a28.09,28.09,0,0,0,0,39.7,28.11,28.11,0,0,0,39.74,0l44,-44L41.91,-20A30,30,0,0,0,84.3,-20L213.16,-148.87Z"
+        android:fillColor="#6ab343"/>
+  </group>
+</vector>

RecyclerViewDiffUtilDataBinding/app/src/main/res/drawable/ic_launcher_sleep_tracker_foreground.xml

@@ -0,0 +1,77 @@
+<!--
+  ~ Copyright 2019, The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~     http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="108dp"
+        android:height="108dp"
+        android:viewportWidth="512"
+        android:viewportHeight="512">
+  <path
+      android:pathData="M35.58,297.76l6.18,-7.64l98.76,-8.5l100.14,101.33l-20,86.04l-7.5,6.29l-126.86,-7.63l-50.72,-169.89z"
+      android:fillColor="#fff"/>
+  <path
+      android:pathData="M389,302.51q-28.14,0 -47.68,19.54T321.8,369.73q0,28.15 19.55,48.08T389,437.74q28.14,0 48.08,-19.93T457,369.73q0,-28.14 -19.93,-47.68T389,302.51Z"
+      android:fillColor="#6ab343"/>
+  <path
+      android:pathData="M389.17,326.32a43.23,43.23 0,0 0,-43.55 43.55A42.84,42.84 0,0 0,358.28 401a41.6,41.6 0,0 0,30.89 12.92,44.09 44.09,0 0,0 44.05,-44.06A41.61,41.61 0,0 0,420.31 339,42.91 42.91,0 0,0 389.17,326.32Z"
+      android:fillColor="#f5f5f5"/>
+  <path
+      android:pathData="M389.4,363.79L389.4,340.35"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
+      android:fillColor="#00000000"
+      android:strokeColor="#6ab343"
+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M394.5,373.69L412.12,384.46"
+      android:strokeLineJoin="round"
+      android:strokeWidth="10"
+      android:fillColor="#00000000"
+      android:strokeColor="#6ab343"
+      android:strokeLineCap="round"/>
+  <path
+      android:pathData="M389.39,363.79a6.25,6.25 0,0 0,-6.3 6.3,6.2 6.2,0 0,0 1.83,4.5 6,6 0,0 0,4.47 1.87,6.37 6.37,0 0,0 6.36,-6.37 6,6 0,0 0,-1.86 -4.47A6.21,6.21 0,0 0,389.39 363.79Z"
+      android:strokeWidth="7"
+      android:fillColor="#f5f5f5"
+      android:strokeColor="#6ab343"/>
+  <group>
+    <clip-path android:pathData="M584.94,0h512v512h-512z M 0,0"/>
+    <path
+        android:pathData="M448.55,437.05,709.34,697.84a8.72,8.72,0,0,0,12.32,0l325.45,-325.45a8.72,8.72,0,0,0,0,-12.32L778,91a18.84,18.84,0,0,0,-26.65,0L442,382.4l-2.36,5.16A44.07,44.07,0,0,0,448.55,437.05Z"
+        android:fillColor="#43a047"/>
+    <path
+        android:pathData="M440.25,415.17l275.52002,275.52l335.0,-334.99l-278.15002,-278.15002l-334.26,328.40002l1.8900146,9.220001z"
+        android:fillColor="#c0ca33"/>
+    <path
+        android:pathData="M544.72,137.12h393.36v473.76h-393.36z"
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