Flutter Module in Android App

MAkif DERE
Jan 19 · 3 min read

Today I’m going to import a Flutter module into an existing Android app. Moreover, I’ll call native methods from that Flutter screen. Because I solved the issue which I mentioned in the last paragraph of my previous story, thanks to Muhannad Fakhouri.

I created a basic Android app and imported a Flutter module. By the FloatingActionButton, I’m starting the FlutterActivity with a route and put a parameter for the title to handle on the Dart side.

FloatingActionButton fab = findViewById(R.id.fab);

fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(
new FlutterActivity
.NewEngineIntentBuilder(MyFlutterActivity.class)
.initialRoute("/second")
.build(getApplicationContext())
.putExtra("title", "Title")

);
}
});

I located MyFlutterActivity.java on the same folder as other java classes and defined the activity in Manifest.xml.

<activity android:name=".MyFlutterActivity"
android:theme="@style/AppTheme"
android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
android:hardwareAccelerated="true"
android:windowSoftInputMode="adjustResize"
/>

Then, I override the onCreate method of MyFlutterActivity to get the title parameter and set it to a global variable:

String title = "";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle extras = getIntent().getExtras();
title = extras.getString("title");
}

And override the configureFlutterEngine to handle the method calls from the Dart side of the app.

@Override
public void configureFlutterEngine(@NonNull FlutterEngine flutterEngine) {
GeneratedPluginRegistrant.registerWith(flutterEngine);

new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), CHANNEL).setMethodCallHandler(((methodCall, result) -> {
if (methodCall.method.equals("getBatteryLevel")) {
result.success("batteryLevel");
} else if (methodCall.method.equals("getTitle")) {
result.success(title); // It returns "Title".
} else {
result.notImplemented();
}
}));
}

Now, I can easily call the related invokeMethod in the initState of SecondScreen.dart to get the title that passed as an argument from the native side.

@override
void initState() {
super.initState();

getTitle();
}

getTitle() async {
String res = await platformMethodChannel.invokeMethod('getTitle');

setState(() {
title = res;
});
}

Voila! The parameter “Title” is on the screen.

And I can invoke the other methods like getBatteryLevel in this Flutter screen.

void _incrementCounter() async {
try {
String response =
await platformMethodChannel.invokeMethod('getBatteryLevel');

print(response);
setState(() {
title = response;
});
} on PlatformException catch (e) {
print("e.message");
print(e.message);
}

setState(() {
_counter++;
});
}

The parameter has changed as demonstrated below.

You can access the GitHub repo about this story from here:

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