title: How to properly clear all notification once clicked?
body: <p>I send a few notification on the notification bar, i wanted to clear all of it when one of the notification is clicked. For now I clear one by one by using Flag. I know <code>notificationManager.cancelAll()</code> could clear all the notification but where should i put so that i can trigger once one of the notification is clicked.</p>
  
  <pre><code> private static void generateNotification(Context context, String message) {
      int icon = R.drawable.ic_launcher;
      long when = System.currentTimeMillis();
      NotificationManager notificationManager = (NotificationManager)
              context.getSystemService(Context.NOTIFICATION_SERVICE);
      Notification notification = new Notification(icon, message, when);
      String title = context.getString(R.string.app_name); 
      Intent notificationIntent = new Intent(context, MainActivity.class);
  
      // set intent so it does not start a new activity
      notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP |
              Intent.FLAG_ACTIVITY_SINGLE_TOP);
      PendingIntent intent =
              PendingIntent.getActivity(context, 0, notificationIntent, 0);
      notification.setLatestEventInfo(context, title, message, intent);
      notification.flags |= Notification.FLAG_AUTO_CANCEL;
  
      notificationManager.notify(msgid, notification);  
      //notificationManager.cancelAll(); //i wan to clear all when the notification is clicked, where should i put this line?
  }
  </code></pre>