Firebase (FCM): open activity and pass data on notification click. android : <p>There should be clear implementation of how to work with Firebase notification and data. I read many answers but can't seem to make it work. here are my steps:</p>

<p>1.) I am passing notification and data to android in PHP and it seems to be fine:</p>

<pre><code>$msg = array
    (
         "body" =&gt; $body,
         "title" =&gt; $title,
         "sound" =&gt; "mySound"
    );

    $data = array
    (

         "user_id" =&gt; $res_id,
         "date" =&gt; $date,
         "hal_id" =&gt; $hal_id,
         "M_view" =&gt; $M_view
    );

    $fields = array
    (
        'registration_ids' =&gt; $registrationIds,
        'notification' =&gt; $msg,
        'data' =&gt; $data
    );



    $headers = array
    (
        'Authorization: key='.API_ACCESS_KEY,
        'Content-Type: application/json'
    );

    $ch = curl_init();
    curl_setopt( $ch,CURLOPT_URL, 'https://android.googleapis.com/gcm/send' );
    curl_setopt( $ch,CURLOPT_POST, true );
    curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
    curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
    curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
    curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ) );
    $result = curl_exec($ch );
    curl_close( $ch );
</code></pre>

<p>2.) when notification and data is received in Android it shows notification. When I click on this notification it opens app. But I can not figure out the way to handle the data when the app is opened. There are couple differences when app is in foreground and backround. The code that I have now is the following: </p>

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

private static final String TAG = "MyFirebaseMsgService";

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {

    String user_id = "0";
    String date = "0";
    String cal_id = "0";
    String M_view = "0";

    if (remoteMessage.getData().size() &gt; 0) {
        Log.d(TAG, "Message data payload: " + remoteMessage.getData());
        user_id = remoteMessage.getData().get("user_id");
        date = remoteMessage.getData().get("date");
        hal_id = remoteMessage.getData().get("hal_id");
        M_view = remoteMessage.getData().get("M_view");
    }

    //Calling method to generate notification
    sendNotification(remoteMessage.getNotification().getBody(), user_id, date, hal_id, M_view);
}

private void sendNotification(String messageBody, String user_id, String date, String hal_id, String M_view) {
    Intent intent = new Intent(this, MainActivity.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);

    intent.putExtra("fcm_notification", "Y");
    intent.putExtra("user_id", user_id);
    intent.putExtra("date", date);
    intent.putExtra("hal_id", hal_id);
    intent.putExtra("M_view", M_view);
    int uniqueInt = (int) (System.currentTimeMillis() &amp; 0xff);
    PendingIntent pendingIntent = PendingIntent.getActivity(getApplicationContext(), uniqueInt, intent,
            PendingIntent.FLAG_UPDATE_CURRENT);

    Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this);
    notificationBuilder.setSmallIcon(R.drawable.ic_launcher)
            .setContentText(messageBody)
            .setAutoCancel(true)
            .setSound(defaultSoundUri)
            .setContentIntent(pendingIntent);

    NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
    notificationManager.notify(0, notificationBuilder.build());
}}
</code></pre>

<p>3.) When I use the code above and when I click on notification all it does it opens the app if in background. If app in foreground then on notification click it simply dismisses notification. However, I want to receive data and open specific Activity in both scenarios (background and foreground). I have in MainActivity the following code, but I am not able to get data. fcm_notification, date, hal_id returns null.</p>

<pre><code>public class MainActivity extends Activity {
 UserFunctions userFunctions;

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

@Override
protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);
    setIntent(intent);
    Intent intent_o = getIntent();
}

@Override
protected void onResume() {
    super.onResume();
    userFunctions = new UserFunctions();
    if(userFunctions.isUserLoggedIn(getApplicationContext())){
        Intent intent_o = getIntent();
        String fcm_notification = intent_o.getStringExtra("fcm_notification") ;
        String user_id = intent_o.getStringExtra("user_id");
        String date = intent_o.getStringExtra("date");
        String hal_id = intent_o.getStringExtra("hal_id");
        String M_view = intent_o.getStringExtra("M_view");
        Intent intent = new Intent(this, JobList.class);

        // THIS RETURNS NULL, user_id = null
        System.out.print("FCM" + user_id);
        startActivity(intent);
        finish();
    }else{
        // user is not logged in show login screen
        Intent login = new Intent(this, LoginActivity.class);
        startActivity(login);
        // Closing dashboard screen
        finish();
    }
}}
</code></pre>

<p>IF anyone can direct or advice how can I retrieve data in MainActivity.java from Firebase in either scenario (foreground or background) that would be fantastic. </p>
