Android Firebase Messaging calling getToken too soon after starting service?

Question

I think I designed my use of Firebase Messaging in my Android app in a way that recently caused a problem.

When a user indicates he wants to receive messages, I then start my FirebaseMessagingService and immediately go get the token in my Activity:

Intent i = new Intent(this, myFirebaseMessagingService.class);
startService(i);

FirebaseApp.initializeApp(this);

FirebaseMessaging.getInstance().getToken().addOnCompleteListener(new OnCompleteListener<String>() {
    @Override
    public void onComplete(@NonNull Task<String> task) {
        if (task.isSuccessful()) {
            // send token to server...

A large number of devices recently did not get a token the first time using this method. The second time the user went to this Activity, the service was already running, so the devices got their token successfully using the same method.

Am I right that the token isn't generated the first time because I'm calling getToken() too soon after starting the service? (I have not been able to reproduce this while debugging.)

If so, I'm thinking the solution is to just start the service when the app is launched, so that by the time the user gets to this Activity, the token can be obtained successfully.

(Another possibility is that the service fails to start the first time but does start the second time, but I'm not sure why or how to detect that.)

Note the app is using Firebase Messaging version 22.0.0. I need to update it, of course, but I'm not sure the latest version solves this problem.

Answer 1

In MainActivity, you are calling getToken() before the service is started. The service is started asynchronously, so it's possible that the service is not started when getToken() is called. You can try to call getToken() in the onServiceConnected() callback of the service connection. Try in your MainActivity:

Intent i = new Intent(this, myFirebaseMessagingService.class);
startService(i);

FirebaseApp.initializeApp(this);

ServiceConnection serviceConnection = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        FirebaseMessaging.getInstance().getToken().addOnCompleteListener(new OnCompleteListener<String>() {
            @Override
            public void onComplete(@NonNull Task<String> task) {
                if (task.isSuccessful()) {
                    // send token to server...
                }
            }
        });
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
    }
};

bindService(i, serviceConnection, Context.BIND_AUTO_CREATE); 

Answer 2

Just curious to know that why are you initialising service this way? You can declare your service in AndroidManfiest.xml with tag and add filter as:

<intent-filter>
<action android:name="com.google.firebase.MESSAGING_EVENT" />                </intent-filter>

That's it. Your messaging service will start working. Also you can get FCM token with the above code with no issues. PS. Try to update the SDK to have latest implementations.