Android Oreo Notification

Question

private void showNotification(){
    Intent notificationIntent = new Intent(mContext, MainActivity.class);
    notificationIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
    PendingIntent pendingIntent = PendingIntent.getActivity(mContext, 0, notificationIntent, 0);
     Notification notification = new NotificationCompat.Builder(mContext)
             .setContentTitle("myApp")
             .setTicker("myApp")
             .setContentText("Application is running")
             .setContentIntent(pendingIntent)
             .build();
     // starts this service as foreground
     startForeground(NOTIFICATION_ID, notification);
}

"Notification" above is not working (OREO) How can I redesign according to Oreo? Please help me.