'''public void subscribeToTopic(String topic){
FirebaseMessaging.getInstance().subscribeToTopic(topic)
.addOnCompleteListener(new OnCompleteListener<Void>() {
@Override
public void onComplete(@NonNull Task<Void> task) {
String msg = "subscribed to topic \""+topic+"\"";
if (!task.isSuccessful()) {
msg = "msg_subscribe_failed";
}
Log.d(TAG, msg);
Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
}
});
}'''
Logcat
E/FirebaseMessaging: Topic operation failed: SERVICE_NOT_AVAILABLE. Will retry Topic operation.