How to retrive List of String from method channel

Question

I want to retrieve List of String from native Android to flutter via Method Channel. This list of string is all contact phone number. My current code:

 new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
        new MethodChannel.MethodCallHandler() {
          @Override
          public void onMethodCall(MethodCall call, MethodChannel.Result result) {
            if (call.method.equals("getContacts")) {
              contacts = getContactList();

              if (contacts != null) {
                result.success(contacts);
              } else {
                result.error("UNAVAILABLE", "not avilable", null);
              }
            } else {
              result.notImplemented();
            }
          }
        });

In Flutter:

final Iterable result = await platform.invokeMethod('getContacts');
  contactNumber = result.toList();

But I'm not getting any response from flutter. How to retrive just phone number from native android to flutter?

Answer 1

Here is how i did it.

Android Native code (Send list with Strings):

new MethodChannel(getFlutterView(), CHANNEL).setMethodCallHandler(
            new MethodCallHandler() {
                @Override
                public void onMethodCall(MethodCall call, Result result) {
                    if (call.method.equals("samples.flutter.io/contact")) {
                        final List<String> list = new ArrayList<>();
                        list.add("Phone number 1");
                        list.add("Phone number 2");
                        list.add("Phone number 3");

                        result.success(list);
                    } else {
                        result.notImplemented();
                    }
                }
            }
    );

Flutter Code:

List<dynamic> phoneNumbersList = <dynamic>[];

Future<List<String>> _getList() async {
   phoneNumbersList = await methodChannel.invokeMethod('samples.flutter.io/contact');
   print(phoneNumberList[0]);
   return phoneNumberList;
}

Answer 2

Null Safe Code

Java side (sending data):

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

    new MethodChannel(flutterEngine.getDartExecutor().getBinaryMessenger(), "foo_channel")
            .setMethodCallHandler((methodCall, result) -> {
                if (methodCall.method.equals("methodInJava")) {
                    // Return your List here.
                    List<String> list = new ArrayList<String>();
                    list.add("A");
                    list.add("B");
                    list.add("C");
                    result.success(list);
                }
            });
}

Dart side (receiving data):

void getList() async {
  var channel = MethodChannel('foo_channel');
  List<String>? list = await channel.invokeListMethod<String>('methodInJava');
  print(list); // [A, B, C]
}