title: How to display multiple notification as a group?
body: <p>here is my code for notification. it generate a new notification each time        </p>
  
  <pre><code>Random random = new Random();
  int m = random.nextInt(9999 - 1000);    
  NotificationCompat.Builder mBuilder =new NotificationCompat.Builder(context)
                      .setSmallIcon(R.drawable.quemark1)
                      .setContentTitle("New Message")
                      .setContentText(message)
  Intent intent = new Intent(this, ActivityMain.class);
  TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
  stackBuilder.addParentStack(ActivityMain.class);
  stackBuilder.addNextIntent(intent);
  PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);
  mBuilder.setContentIntent(resultPendingIntent);
  NotificationManager mNotificationManager = (NotificationManager)     context.getSystemService(Context.NOTIFICATION_SERVICE);
  mBuilder.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_VIBRATE);
  mBuilder.setAutoCancel(true);
  mNotificationManager.notify(m, mBuilder.build());
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/TacX2.jpg" rel="noreferrer">here is the output of my code</a></p>