How to send notification from one android application to other android application?

Question

I've created two different android applications, one for the admin panel which has only one user itself, and the other one which will be installed on other android devices. As the admin adds notifications in his application, all users will get the notifications. what should I do? How to implement this?

Answer 1

Use firebase FCM for sending the push notifications to android devices. Here you will find lot of options. https://firebase.google.com/docs/cloud-messaging

Answer 2

You sound a beginner so I will explain in simple words first.

• You need a server side script which can trigger the notification sending code, If you are running PHP as your server side language then you can use my code below.
• Then you need your User application to subscribed to a topic. A topic is just a custom string. You will use this topic string to send notification to specific user or user groups.
• From your Admin application you need to call that PHP script on server that can trigger notification. I assume you already know how to call a PHP script, It's same as calling the normal API to do operations in Database.

Having known the process flow you need to follow below steps.

• Follow this tutorial to start a Firebase project and acquire FCM Notification functionality. Get firebase api key from the console.

• In your User application subscribe to a topic using the code below. Put this code in the onCreate method of the Activity after user logs into app. Unsubscribe the topic if you want user to stop receiving notifications.

  FirebaseMessaging.getInstance().subscribeToTopic("your topic name here"); //to subscribe
  FirebaseMessaging.getInstance().unsubscribeFromTopic("your topic name here"); //to unsubscribe
  

• Put this code in a PHP file, you need to call this to trigger notification.

   define('FIREBASE_API_KEY', 'your firebase api key');
  
   $title = "this will display as notification title";
   $body = "subject of notification";
   $topic = "your topic name";
  
   $message["title"] = $title;
   $message["body"] = $body;
  
    $fields = array(
         'to' => '/topics/'.$topic,
         'notification' => $message,
     );
     // Set POST variables
     $url = 'https://fcm.googleapis.com/fcm/send';
  
     $headers = array(
         'Authorization: key=' . FIREBASE_API_KEY,
         'Content-Type: application/json'
     );
     // Open connection
     $ch = curl_init();
  
     // Set the url, number of POST vars, POST data
     curl_setopt($ch, CURLOPT_URL, $url);
  
     curl_setopt($ch, CURLOPT_POST, true);
     curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
     curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  
     // Disabling SSL Certificate support temporarly
     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
  
     curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
  
     // Execute post
   $result='';
   if($title!=null){ 
     $result = curl_exec($ch);
  
       if ($result === FALSE) {
           die('Curl failed: ' . curl_error($ch));
       }
   }  
     // Close connection
     curl_close($ch);
  

• Now call this PHP script from your Admin application. You can pass parameters according to your needs. You will be able to get a notification in your User app.

You can customize the notification in your Android code, like playing a specific sound. For that you need to follow the official document guide I linked above.