How to add flutter_boost to an existing Android project. This demo was done on macOS. On Windows, change the paths to Windows format.

The Flutter side

  1. Create a new flutter module

    flutter create -t module flutter_module

  2. Add the flutter_boost dependency in pubspec.yaml

    dependencies:
  flutter_boost:

  3. Run flutter build apk With flutter_boost 0.400 this throws an error. The key part is:

    * What went wrong:
A problem occurred evaluating project ':flutter_boost'.
> Plugin with id 'kotlin-android-extensions' not found.

    It’s not hard to see it’s a missing kotlin dependency. Let’s fix that.

  4. From the project root run flutter make-host-app-editable When it finishes you’ll see android and ios folders appear.

  5. Add the kotlin dependency in android/build.gralde

     buildscript {
+    ext.kotlin_version = '1.3.21'
	repositories {
		google()
		jcenter()
@@ -8,6 +9,7 @@ buildscript {

	dependencies {
		classpath 'com.android.tools.build:gradle:3.2.1'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
	}
}

    Run flutter build apk again and it succeeds.

  6. Copy the files under flutter_boost/example/lib into the lib directory

That’s the Flutter side prepared.

The Android side

  1. Create a project with Android Studio

    If you already have a project you can skip this step

  2. Add kotlin support to the App module, and add the following to settings.gradle

    setBinding(new Binding([gradle: this]))
evaluate(new File('../flutter_module/.android/include_flutter.groovy'))   // keep the Android project and the flutter module in the same directory

    Run gralde sync. You should now see three new projects in your build: Flutter-flutter, flutter_boost and xservice_kit

    If you hit the error below, change the gradle version to 4.10.2

    ERROR: Unable to resolve dependency for ':flutter@dynamicProfile/compileClasspath': Could not resolve project :xservice_kit.
 Show Details
 Affected Modules: flutter

 ERROR: Unable to resolve dependency for ':flutter@dynamicProfile/compileClasspath': Could not resolve project :flutter_boost.
 Show Details
 Affected Modules: flutter

  3. Add the dependencies below to the build.gradle file in the flutterservice directory

    implementation project(path: ':flutter')
implementation project(":flutter_boost")

  4. Copy everything from flutter_boost/example/android and create a new MyApplication class:

    class MyApplication : FlutterApplication(), IPlatform {
	override fun onCreate() {
		super.onCreate()
		FlutterBoostPlugin.init(this)
	}
	override fun getApplication(): Application {
		return this
	}

	override fun getMainActivity(): Activity? {
		return MainActivity.sRef.get()
	}

	override fun isDebug(): Boolean {
		return true
	}

	override fun startActivity(context: Context?, url: String?, requestCode: Int): Boolean {
		return false
	}

	override fun getSettings(): MutableMap<Any?, Any?> {
		return HashMap()
	}

}

    Then point the manifest at this Application

  5. Add a weak reference in MainActivity to hold MainActivity

    class MainActivity : AppCompatActivity() {
	override fun onCreate(savedInstanceState: Bundle?) {
		super.onCreate(savedInstanceState)
		setContentView(R.layout.activity_main)
		sRef = WeakReference(this)
	}

	companion object {

		var sRef: WeakReference<Activity?> = WeakReference(null)
	}
}

  6. Create FlutterPageActivity, and remember to add it to the manifest

    class FlutterPageActivity:BoostFlutterActivity() {
	override fun getContainerParams(): MutableMap<Any?, Any?> {
		return HashMap()
	}

	override fun onRegisterPlugins(registry: PluginRegistry?) {
		GeneratedPluginRegistrant.registerWith(registry)
	}

	override fun getContainerName(): String {
		return "flutterPage"
	}
}

  7. Give the textview an id in the layout

            android:text="Hello World!"
        android:id="@+id/tvHello"
        app:layout_constraintBottom_toBottomOf="parent"

  8. Add a click listener in MainActivity

    tvHello.setOnClickListener {
	startActivity(Intent(applicationContext, FlutterPageActivity::class.java))
}

  9. Run the Android project. If you hit errors, fix them following the prompts.

  10. Click Hello world and a Flutter page opens. At this point you’ve gone from a native page to a Flutter page.

  11. Change the startActivity function in MyApplication to the code below:

 override fun startActivity(context: Context?, url: String?, requestCode: Int): Boolean {
        if (url?.contains("sample://nativePage") == true) {
            context?.startActivity(Intent(context, MainActivity::class.java))
            return true
        }
        return false
    }

Click open native page in the Flutter page and the activity reopens.

That’s the round trip between both sides done. Welcome to the Flutter pit.