@Override
protected void onMessage(Context context, Intent data) {
    String message = data.getExtras().getString("message");

    displayMessage(context, message);
    generateNotification(context, message);
}

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, GCMMessageView.class);

    notificationIntent.putExtra("message", message);
    // 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;

    // Play default notification sound
    notification.defaults |= Notification.DEFAULT_SOUND;

    // Vibrate if vibrate is enabled
    notification.defaults |= Notification.DEFAULT_VIBRATE;
    notificationManager.notify(0, notification);
}

notificationManager.notify(ID, notification);

PendingIntent intent = PendingIntent.getActivity(context, nid,notificationIntent, 0);