//in onCreate()
mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE);
showNotification();

private void showNotification() {
    Notification notification = new Notification(R.drawable.icon, "Scanner Service Started", System.currentTimeMillis());
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0); //this is how we will launch an Activity when the user clicks the notification
    notification.setLatestEventInfo(this, getText(R.string.app_name), "Scanner Not Connected", contentIntent);
    notification.flags|=Notification.FLAG_ONGOING_EVENT;
    mNM.notify(NOTIFICATION_CONNECTION_CHANGED, notification);  //send the notification to the system, to be displayed in the notification bar
}

private void updateNotification(String update) {
    Notification notification = new Notification(R.drawable.icon, update, System.currentTimeMillis());
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, MainActivity.class), 0); //this is how we will launch an Activity when the user clicks the notification
    notification.setLatestEventInfo(this, getText(R.string.app_name), update, contentIntent);
    notification.flags|=Notification.FLAG_ONGOING_EVENT;
    mNM.notify(NOTIFICATION_CONNECTION_CHANGED, notification);  //send the notification to the system, to be displayed in the notification bar
}