Update Android files in isolate_example (#1017)

isolate_example/android/app/build.gradle

@@ -26,7 +26,16 @@ apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 30
+    compileSdkVersion flutter.compileSdkVersion
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
@@ -35,8 +44,8 @@ android {
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "dev.flutter.isolate_example"
-        minSdkVersion 16
-        targetSdkVersion 30
+        minSdkVersion flutter.minSdkVersion
+        targetSdkVersion flutter.targetSdkVersion
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName
     }

isolate_example/android/app/src/main/AndroidManifest.xml

@@ -2,9 +2,11 @@
     package="dev.flutter.isolate_example">
    <application
         android:label="isolate_example"
+        android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"
+            android:exported="true"
             android:launchMode="singleTop"
             android:theme="@style/LaunchTheme"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
@@ -18,15 +20,6 @@
               android:name="io.flutter.embedding.android.NormalTheme"
               android:resource="@style/NormalTheme"
               />
-            <!-- Displays an Android View that continues showing the launch screen
-                 Drawable until Flutter paints its first frame, then this splash
-                 screen fades out. A splash screen is useful to avoid any visual
-                 gap between the end of Android's launch screen and the painting of
-                 Flutter's first frame. -->
-            <meta-data
-              android:name="io.flutter.embedding.android.SplashScreenDrawable"
-              android:resource="@drawable/launch_background"
-              />
             <intent-filter>
                 <action android:name="android.intent.action.MAIN"/>
                 <category android:name="android.intent.category.LAUNCHER"/>

isolate_example/android/app/src/main/res/values-night/styles.xml

@@ -10,7 +10,7 @@
          This theme determines the color of the Android Window while your
          Flutter UI initializes, as well as behind your Flutter UI while its
          running.
-         
+
          This Theme is only used starting with V2 of Flutter's Android embedding. -->
     <style name="NormalTheme" parent="@android:style/Theme.Black.NoTitleBar">
         <item name="android:windowBackground">?android:colorBackground</item>

isolate_example/android/app/src/main/res/values/styles.xml

@@ -10,7 +10,7 @@
          This theme determines the color of the Android Window while your
          Flutter UI initializes, as well as behind your Flutter UI while its
          running.
-         
+
          This Theme is only used starting with V2 of Flutter's Android embedding. -->
     <style name="NormalTheme" parent="@android:style/Theme.Light.NoTitleBar">
         <item name="android:windowBackground">?android:colorBackground</item>