Platform specific code error: MissingPluginException - flutter

Question

I want to send an Notification in Flutter, so I set up my platform specific code (only Android) but I get the following error back:
Unhandled Exception: MissingPluginException(No implementation found for method send_notification on channel reminderChannel)
I already cleaned the project but still not working.
Future to invoke method:
const platform = const MethodChannel("reminderChannel");
Future<void> invokeMethod() async {
try {
//FIXME Missing plugin
int testValue = await platform.invokeMethod("send_notification");
} on PlatformException catch (e) {}
}
invokeMethod();
mainActivity:
private static final String notificationChannel = "reminderChannel";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
GeneratedPluginRegistrant.registerWith(this);
new MethodChannel(getFlutterView(), notificationChannel).setMethodCallHandler(
new MethodCallHandler() {
#Override
public void onMethodCall(MethodCall methodCall, Result result) {
if (methodCall.method.equals("send_notification")) {
System.out.print("Android Method called");
result.success(5);
} else {
result.notImplemented();
}
}
}
);
}
I want that the testValue variable in invokeMethod equals 5.
Thanks for helping.

Answer 1

I suspect your channel is deallocated at the end of the method.
So keep a reference to the MethodChannel in your acivity:
private static final String notificationChannel = "reminderChannel";
private MethodChannel mainChannel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
GeneratedPluginRegistrant.registerWith(this);
reminderChannel = new MethodChannel(getFlutterView(), notificationChannel)
reminderChannel.setMethodCallHandler(
new MethodCallHandler() {
#Override
public void onMethodCall(MethodCall methodCall, Result result) {
if (methodCall.method.equals("send_notification")) {
System.out.print("Android Method called");
result.success(5);
} else {
result.notImplemented();
}
}
}
);
}