Notification

 NotificationManager manager;

private void createNotification() {
        NotificationCompat.Builder mBuilder =
                new NotificationCompat.Builder(this)
                        .setSmallIcon(R.drawable.notification)
                        .setContentTitle("My notification")
                        .setOngoing(true)
                        .setContentText("Hello World!");
        Intent notificationIntent = new Intent(this, MainActivity.class);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        mBuilder.setContentIntent(contentIntent);

        manager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        manager.notify(0, mBuilder.build());


    }
   void cancelNot(){
       manager.cancel(0);
    }