[Pong] Bouncing ball problem

Newbie & Debugging Questions
#1

Hey guys, I’m pretty much new to the Java Graphics part, and I have a couple questions as well.
Anyway, I was trying create a Pong game , and I’m already having some trouble with the ball moving part.
I don’t understand why isn’t the ball moving at all, all it does is flicker in the same place.
I usually extend JComponent in a class, and draw everything inside the paintComponent() method, so I just wanted to try something new I read, but yeah I just cant figure out what am I doing wrong ???

public class GUI {
	JFrame frame;
	Ball ball = new Ball();
	GamePanel gamepanel = new GamePanel();
	BallEngine engine = new BallEngine(gamepanel);

	public GUI() {
		frame = new JFrame("Pong");
		frame.add(gamepanel);
		frame.setSize(400, 400);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

	private void execute() {
		frame.setVisible(true);
		engine.start();
	}

	public static void main(String[] args) {
		GUI gui = new GUI();
		gui.execute();
	}
}


public class GamePanel extends JPanel {

	private static final long serialVersionUID = 1L;
	Ball ball = new Ball();
	Paddle paddle = new Paddle();

	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		ball.paintBall(g);
		paddle.paintPaddle(g);
	}

	public void update() {
		ball.moveBall();
		repaint();
	}
}



public class Ball extends JLabel {
	private static final long serialVersionUID = 1L;
	int x = 150;
	int y = 150;

	int xVelocity = 1;
	int yVelocity = 1;

	public void paintBall(Graphics g) {
		g.fillOval(x, y, 25, 25);
	}

	public void moveBall() {
		if (x >= (getWidth() - 50) || x <= 0) {
			xVelocity = -xVelocity;
		}
		if (y >= getHeight() - 50 || y <= 0)
			yVelocity = -yVelocity;
		x += xVelocity;
		y += yVelocity;
	}
}



public class BallEngine extends Thread {
	GamePanel gamepanel = new GamePanel();

	public BallEngine(GamePanel gamepanel) {
		this.gamepanel = gamepanel;
	}

	@Override
	public void run() {
		while (true) {
			try {
				gamepanel.update();

			} catch (Exception e) {
			}
		}
	}
}