Add View Binding sample (#11)

* Create ViewBinding sample app

* Implement ViewBinding sample app

* Add MainActivity instrumentation tests

* Add FragmentBind and FragmentInflate instrumentation tests

* Create README.md

ViewBindingSample/.gitignore

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+*.iml
+.gradle
+/local.properties
+/.idea/*
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+.cxx
+local.properties

ViewBindingSample/README.md

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+# View Binding
+
+Android sample app to learn about view binding in Android. It mainly showcases:
+- Enabling view binding through the app's build file.
+- Setting up binding instances in activities.
+- Setting up binding instances in Fragments using both the `inflate(LayoutInflater)` and `bind(View)` static methods.
+- Accessing and interacting with views through the binding instances.
+- Setting up layout files differently for different configurations, and accessing them through the binding instances with their nullable references.
+
+![View binding sample - inflate](https://github.com/husaynhakeem/android-playground/blob/master/ViewBindingSample/art/view_binding_portrait.png)
+![View binding sample - bind](https://github.com/husaynhakeem/android-playground/blob/master/ViewBindingSample/art/view_binding_landscape.png)
+
+### Resources to learn about view binding
+- [The official documentation on View Binding](https://developer.android.com/topic/libraries/view-binding)

ViewBindingSample/app/.gitignore

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+/build

ViewBindingSample/app/build.gradle

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+plugins {
+    id "com.android.application"
+    id "kotlin-android"
+}
+
+android {
+    compileSdkVersion 30
+
+    defaultConfig {
+        applicationId "com.husaynhakeem.viewbindingsample"
+        minSdkVersion 21
+        targetSdkVersion 30
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+    viewBinding {
+        enabled = true
+    }
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    implementation "androidx.core:core-ktx:1.3.2"
+    implementation "androidx.appcompat:appcompat:1.2.0"
+    implementation "androidx.constraintlayout:constraintlayout:2.0.4"
+    implementation "com.google.android.material:material:1.2.1"
+    androidTestImplementation "androidx.test.ext:junit:1.1.2"
+    androidTestImplementation "androidx.test.espresso:espresso-core:3.3.0"
+    androidTestImplementation "androidx.test:core-ktx:1.3.0"
+    debugImplementation("androidx.fragment:fragment-testing:1.2.5") {
+        exclude group: 'androidx.test', module: 'core'
+    }
+}

ViewBindingSample/app/src/androidTest/java/com/husaynhakeem/viewbindingsample/FragmentBindTest.kt

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+package com.husaynhakeem.viewbindingsample
+
+import android.content.pm.ActivityInfo
+import androidx.fragment.app.testing.launchFragmentInContainer
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.assertion.ViewAssertions.doesNotExist
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class FragmentBindTest {
+
+    @Test
+    fun doNotShowSubtitle_inPortraitOrientation() {
+        // Arrange
+        val scenario = launchFragmentInContainer { FragmentBind() }
+
+        // Act
+        scenario.onFragment { fragment ->
+            fragment.requireActivity().requestedOrientation =
+                ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
+        }
+
+        // Assert
+        onView(withId(R.id.subtitle)).check(doesNotExist())
+    }
+
+    @Test
+    fun showSubtitle_inLandscapeOrientation() {
+        // Arrange
+        val scenario = launchFragmentInContainer { FragmentBind() }
+
+        // Act
+        scenario.onFragment { fragment ->
+            fragment.requireActivity().requestedOrientation =
+                ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE
+        }
+
+        // Assert
+        onView(withId(R.id.subtitle)).check(matches(isDisplayed()))
+    }
+}

ViewBindingSample/app/src/androidTest/java/com/husaynhakeem/viewbindingsample/FragmentInflateTest.kt

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+package com.husaynhakeem.viewbindingsample
+
+import android.os.Build
+import androidx.fragment.app.testing.launchFragmentInContainer
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.assertion.ViewAssertions.doesNotExist
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Assume.assumeTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class FragmentInflateTest {
+
+    @Test
+    fun doNotShowSubtitle_onApisBelow23() {
+        // Arrange
+        assumeTrue(Build.VERSION.SDK_INT < 23)
+        launchFragmentInContainer { FragmentInflate() }
+
+        // Assert
+        onView(withId(R.id.subtitle)).check(doesNotExist())
+    }
+
+    @Test
+    fun showSubtitle_onApis23AndAbove() {
+        // Arrange
+        assumeTrue(Build.VERSION.SDK_INT >= 23)
+        launchFragmentInContainer { FragmentInflate() }
+
+        // Assert
+        onView(withId(R.id.subtitle)).check(matches(isDisplayed()))
+    }
+}

ViewBindingSample/app/src/androidTest/java/com/husaynhakeem/viewbindingsample/MainActivityTest.kt

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+package com.husaynhakeem.viewbindingsample
+
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.ext.junit.rules.ActivityScenarioRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class MainActivityTest {
+
+    @get:Rule
+    val rule = ActivityScenarioRule(MainActivity::class.java)
+
+    @Test
+    fun showBindFragment_whenBindFragmentButtonClicked() {
+        // Act
+        onView(withId(R.id.bindFragmentButton)).perform(click())
+
+        // Assert
+        onView(withId(R.id.bindFragmentRoot)).check(matches(isDisplayed()))
+    }
+
+    @Test
+    fun showInflateFragment_whenInflateFragmentButtonClicked() {
+        // Act
+        onView(withId(R.id.inflateFragmentButton)).perform(click())
+
+        // Assert
+        onView(withId(R.id.inflateFragmentRoot)).check(matches(isDisplayed()))
+    }
+}

ViewBindingSample/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.husaynhakeem.viewbindingsample">
+
+    <application
+        android:allowBackup="true"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/Theme.ViewBindingSample">
+        <activity android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

ViewBindingSample/app/src/main/java/com/husaynhakeem/viewbindingsample/FragmentBind.kt

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+package com.husaynhakeem.viewbindingsample
+
+import android.os.Bundle
+import android.view.View
+import androidx.fragment.app.Fragment
+import com.husaynhakeem.viewbindingsample.databinding.FragmentBindBinding
+
+class FragmentBind : Fragment(R.layout.fragment_bind) {
+
+    // Instance of the view binding. Should only be accessed while the view is valid, i.e. between
+    // onViewCreated and onDestroyView.
+    private var _binding: FragmentBindBinding? = null
+    private val binding: FragmentBindBinding
+        get() = _binding!!
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        // The layout has already been inflated. Get an instance of the binding class using the
+        // static [bind] method.
+        _binding = FragmentBindBinding.bind(view)
+
+        // Get access to the title TextView, available in all layouts.
+        binding.title.text = getString(R.string.bind_fragment_title)
+
+        // [subtitle] is only available in landscape, and should be null in portrait orientation.
+        binding.subtitle?.text = getString(R.string.bind_fragment_subtitle_landscape)
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+
+        // Set the binding to null, since it should no longer be accessed after the view has been
+        // destroyed.
+        _binding = null
+    }
+}

ViewBindingSample/app/src/main/java/com/husaynhakeem/viewbindingsample/FragmentInflate.kt

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+package com.husaynhakeem.viewbindingsample
+
+import android.os.Build
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import com.husaynhakeem.viewbindingsample.databinding.FragmentInflateBinding
+
+class FragmentInflate : Fragment() {
+
+    // Instance of the view binding. Should only be accessed while the view is valid, i.e. between
+    // onCreateView and onDestroyView.
+    private var _binding: FragmentInflateBinding? = null
+    private val binding: FragmentInflateBinding
+        get() = _binding!!
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        // Set up instance of the binding class to use with this fragment by using the static
+        // [inflate] method.
+        _binding = FragmentInflateBinding.inflate(inflater)
+
+        // Return the root of the binding, which references the LinearLayout.
+        return binding.root
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        // Get access to the title TextView, available in all layouts.
+        binding.title.text = getString(R.string.inflate_fragment_title)
+
+        // [subtitle] is only available in api levels 23 and above, and should be null in devices
+        // running on older versions.
+        val apiLevel = Build.VERSION.SDK_INT
+        binding.subtitle?.text = getString(R.string.inflate_fragment_subtitle_pre_api_23, apiLevel)
+    }
+
+    override fun onDestroyView() {
+        super.onDestroyView()
+
+        // Set the binding to null, since it should no longer be accessed after the view has been
+        // destroyed.
+        _binding = null
+    }
+}

ViewBindingSample/app/src/main/java/com/husaynhakeem/viewbindingsample/MainActivity.kt

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+package com.husaynhakeem.viewbindingsample
+
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.fragment.app.Fragment
+import com.husaynhakeem.viewbindingsample.databinding.ActivityMainBinding
+
+class MainActivity : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        // Set up instance of the binding class to use within this Activity.
+        val binding = ActivityMainBinding.inflate(layoutInflater)
+
+        // Set the root view of the binding as the active view on the screen.
+        setContentView(binding.root)
+
+        // Set OnClickListeners on the buttons
+        binding.bindFragmentButton.setOnClickListener {
+            switchFragment(FragmentBind())
+        }
+        binding.inflateFragmentButton.setOnClickListener {
+            switchFragment(FragmentInflate())
+        }
+
+        // Initially show Bind fragment
+        if (savedInstanceState == null) {
+            setFragment(FragmentBind())
+        }
+    }
+
+    private fun setFragment(fragment: Fragment) {
+        supportFragmentManager.beginTransaction()
+            .add(R.id.content, fragment)
+            .commit()
+    }
+
+    private fun switchFragment(fragment: Fragment) {
+        supportFragmentManager.beginTransaction()
+            .replace(R.id.content, fragment)
+            .commit()
+    }
+}

ViewBindingSample/app/src/main/res/layout-land/fragment_bind.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/bindFragmentRoot"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:gravity="center"
+    android:orientation="vertical">
+
+    <com.google.android.material.textview.MaterialTextView
+        android:id="@+id/title"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textAppearance="@style/TextAppearance.MaterialComponents.Headline4"
+        tools:text="Bind Fragment" />
+
+    <com.google.android.material.textview.MaterialTextView
+        android:id="@+id/subtitle"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:textAppearance="@style/TextAppearance.MaterialComponents.Subtitle1"
+        tools:text="Landscape" />
+
+</LinearLayout>