MyFirebaseMessagingService.java

public class MyFirebaseMessagingService extends FirebaseMessagingService {

    private static final String TAG = "MyFirebaseMsgService";
	private static final int BROADCAST_NOTIFICATION_ID = 1;

    @Override
    public void onDeletedMessages() {
        super.onDeletedMessages();
    }

    /**
     * Called when message is received.
     *
     * @param remoteMessage Object representing the message received from Firebase Cloud Messaging.
     */
    @Override
    public void onMessageReceived(RemoteMessage remoteMessage) {

		String notificationBody = "";
		String notificationTitle = "";
		String notificationData = "";
		try{
		   notificationData = remoteMessage.getData().toString();
		   notificationTitle = remoteMessage.getNotification().getTitle();
		   notificationBody = remoteMessage.getNotification().getBody();
		}catch (NullPointerException e){
		   Log.e(TAG, "onMessageReceived: NullPointerException: " + e.getMessage() );
		}
		Log.d(TAG, "onMessageReceived: data: " + notificationData);
		Log.d(TAG, "onMessageReceived: notification body: " + notificationBody);
		Log.d(TAG, "onMessageReceived: notification title: " + notificationTitle);


		String dataType = remoteMessage.getData().get(getString(R.string.data_type));
		if(dataType.equals(getString(R.string.direct_message))){
			Log.d(TAG, "onMessageReceived: new incoming message.");
			String title = remoteMessage.getData().get(getString(R.string.data_title));
			String message = remoteMessage.getData().get(getString(R.string.data_message));
			String messageId = remoteMessage.getData().get(getString(R.string.data_message_id));
			sendMessageNotification(title, message, messageId);
		}
    }

	/**
	 * Build a push notification for a chat message
	 * @param title
	 * @param message
	 */
	private void sendMessageNotification(String title, String message, String messageId){
		Log.d(TAG, "sendChatmessageNotification: building a chatmessage notification");

		//get the notification id
		int notificationId = buildNotificationId(messageId);

		// Instantiate a Builder object.
		NotificationCompat.Builder builder = new NotificationCompat.Builder(this,
				getString(R.string.default_notification_channel_id));
		// Creates an Intent for the Activity
		Intent pendingIntent = new Intent(this, UserListActivity.class);
		// Sets the Activity to start in a new, empty task
		pendingIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
		// Creates the PendingIntent
		PendingIntent notifyPendingIntent =
				PendingIntent.getActivity(
						this,
						0,
						pendingIntent,
						PendingIntent.FLAG_UPDATE_CURRENT
				);

		//add properties to the builder
		builder.setSmallIcon(R.drawable.ic_android_blue)
				.setLargeIcon(BitmapFactory.decodeResource(getApplicationContext().getResources(),
						R.drawable.ic_android_blue))
				.setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION))
				.setContentTitle(title)
				.setColor(getColor(R.color.blue1))
				.setAutoCancel(true)
				//.setSubText(message)
				.setStyle(new NotificationCompat.BigTextStyle().bigText(message))
				.setOnlyAlertOnce(true);

		builder.setContentIntent(notifyPendingIntent);
		NotificationManager mNotificationManager =
				(NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

		mNotificationManager.notify(notificationId, builder.build());

	}


	private int buildNotificationId(String id){
		Log.d(TAG, "buildNotificationId: building a notification id.");

		int notificationId = 0;
		for(int i = 0; i < 9; i++){
			notificationId = notificationId + id.charAt(0);
		}
		Log.d(TAG, "buildNotificationId: id: " + id);
		Log.d(TAG, "buildNotificationId: notification id:" + notificationId);
		return notificationId;
	}

}