FirebaseMessagingService's onMessageReceived never called

Question

I want to execute some code when my android device receives a push notification. I have the following files: MainActivity.java, MyFirebaseMessagingService.java.
In MainActivity, I start the messaging service:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    startService(new Intent(this, MyFirebaseMessagingService.class));
}

and in MyFirebaseMessagingService, I override the onMessageReceived method as follows:

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    private static final String TAG = MyFirebaseMessagingService.class.getName();

    public MyFirebaseMessagingService() {
        super();
        Log.d(TAG, "init");

    }

    @Override
    public void onNewToken(String token) {
        Log.d(TAG, "app-token: " + token);
    }

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        Log.d(TAG, "on-message-received");
    }

Also, in my AndroidManifest, I have the following setup inside <application>:

<service
    android:name=".MyFirebaseMessagingService"
    android:stopWithTask="false"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
        <action android:name=".MyFirebaseMessagingService" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</service>

I then fire the notification, which appears on my device (it vibrates and I see the notification's title):

curl https://fcm.googleapis.com/fcm/send \                  
  -H "Authorization:key=<my-key>" \
  -H "Content-Type:application/json" \
  -d '{
    "to" : "<device token>",
    "notification": {
      "title": "hello from the server"
    },
    // or:
    "data": {
      "title": "hello from the server"
    },
    "priority": "high"
  }'

However, my code inside onMessageReceived is never executed.
I noticed that the log in onNewToken is also not called, so I'm assuming that the whole class is being ignored entirely.
The log inside MyFirebaseMessagingService's init method is called, so I know the class is registered. Just onMessageReceived isn't called – neither in fore-, nor in background; tried with both "data" and "notification" payloads.

I did a lot of research and there are tons of similar questions, but all fixes I found, like regarding the manifest, or the gradle configurations did not help me.

What am I doing wrong?
[Disclaimer: I'm an absolute beginner to Android development.]

Answer 1

If you look at the docs you will see that onMessageReceived is only called when you are in the foreground without data in your payload, you are only using notification in your payload.

As for starting the service you dont, Google Play Services handles the sending of notifications because of the intent filter <action android:name="com.google.firebase.MESSAGING_EVENT" />. Read the Setup docs

Answer 2

onMessageReceived will only be called in this case if you are sending the the data in both notification and data objects. And that is why on foreground this class gets called, but not on background or kill state and that is why you are unable to show the desired notification. This happens because when the data in notification payload is received, the system handles this and that is why this class is never called. I will suggest you to just send all your data in data payload only and remove notification payload. I too was stuck in this issue but with close assessment i finally figured. And this will resolve all issues in all states.

Answer 3

I finally found the solution to the issue. It's sort of an edge case, but might be useful for someone in the future.

The issue

When I started to implement the push notifications, I was looking into 3rd party services, in this case Pusher's Beams and added that to my gradle configuration.
I'm assuming that the pusher package tried to handle the incoming notification for me, thus my custom class' method wasn't called.

Removing the unused package from gradle & then rebuilding the project fixed the issue for me.