Firebase onMessageReceived(RemoteMessage remoteMessage), is not called when the app is in background
<p>In Firebase <code>onMessageReceived(RemoteMessage remoteMessage)</code>, this method will be called when your app is in Foreground. So, on clicking the notification you can open a different Activity, say <code>NotiicationActivity</code>.</p>

<p>But what if your app is in background, then this method will not be called, and on clicking the notification only a Launcher Activity will be opened. </p>

<p>So how to open the <code>NotificationActivity</code> on clicking the notification even if our app is in background. </p>

<p>My Code is this :</p>

<pre><code>public class MyFirebaseMessagingService extends FirebaseMessagingService {

    private static final String TAG = "MyFirebaseMsgService";

    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {
        Log.d(TAG, "From: " + remoteMessage.getFrom());

        if (remoteMessage.getData().size() &gt; 0) {
            Log.d(TAG, "Message data payload: " + remoteMessage.getData());
        }

        if (remoteMessage.getNotification() != null) {
            Log.d(TAG, "Message Notification Body: " + remoteMessage.getNotification().getBody());
        }

        sendNotification(remoteMessage.getNotification().getBody());

    }

    private void sendNotification(String messageBody) {
        Intent intent = new Intent(this, NewActivity.class);
        intent.putExtra("key", messageBody);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0 /* Request code */, intent,
            PendingIntent.FLAG_ONE_SHOT);
        Bitmap icon2 = BitmapFactory.decodeResource(getResources(),
            R.mipmap.ic_launcher);

        Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this)
        .setSmallIcon(R.mipmap.ic_launcher)
        .setContentTitle("FCM Sample")
        .setContentText(messageBody)
        .setAutoCancel(true)
        .setLargeIcon(icon2)
        .setSound(defaultSoundUri)
        .setContentIntent(pendingIntent);

        NotificationManager notificationManager =
        (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

        notificationManager.notify(new Random().nextInt() /* ID of notification */, notificationBuilder.build());
    }
}
</code></pre>