Comment dessiner une table de jeu en java

package hacktrack.games;

import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.util.HashSet;
import java.util.Set;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class BillardDemo extends JFrame {
	private Set<Ball> balls;
	private Dimension billardSize;
	private int ballSize;
	private int billardBorderWidth;
	private Rectangle playZone;
	private JPanel billard;

	public BillardDemo() {
		super("Demo billard");
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		init();
	}

	private void init() {
		Container c = getContentPane();
		billardSize = new Dimension(640, 360);
		billardBorderWidth = 20;
		ballSize=20;
		playZone = new Rectangle(billardBorderWidth, billardBorderWidth,
				(int) billardSize.getWidth() - billardBorderWidth * 2,
				(int) billardSize.getHeight() - billardBorderWidth * 2);
		balls = new HashSet<BillardDemo.Ball>();
		balls.add(createBall(Color.RED));
		balls.add(createBall(Color.WHITE));
		balls.add(createBall(Color.WHITE));

		billard = new JPanel() {
			@Override
			public void paint(Graphics g) {
				g.setColor(new Color(128, 64, 0));
				g.fillRect(0, 0, (int) billardSize.getWidth(),
						(int) billardSize.getHeight());
				g.setColor(new Color(0, 128, 0));
				g.fillRect((int) playZone.getX(), (int) playZone.getY(),
						(int) playZone.getWidth(), (int) playZone.getHeight());
				if (balls != null) {
					for (Ball ball : balls) {
						g.setColor(new Color(0,83,0));
						g.fillOval(ball.getX()+2, ball.getY()+2, ballSize, ballSize);
						g.setColor(ball.getColor());
						g.fillOval(ball.getX(), ball.getY(), ballSize, ballSize);
					}
				}
			}

		};

		billard.setPreferredSize(billardSize);
		c.add(billard);
		new MoverThread().start();
	}

	private Ball createBall(Color color) {
		int x = (int) (playZone.getX()+ballSize + Math.random() * playZone.getWidth()-ballSize);
		int y = (int) (playZone.getY()+ballSize  + Math.random() * playZone.getHeight()-ballSize);
		double direction = Math.random() * Math.PI * 2;
		double speed = Math.random() * 2 + 2;
		return new Ball(color, x, y, direction, speed);
	}

	class Ball {
		private Color color;
		private int x;
		private int y;
		private double direction;
		private double speed;

		public Ball(Color color, int x, int y, double direction, double speed) {
			this.color = color;
			this.x = x;
			this.y = y;
			this.direction = direction;
			this.speed = speed;
		}

		public Color getColor() {
			return color;
		}

		public void setX(int x) {
			this.x = x;
		}

		public void setY(int y) {
			this.y = y;
		}

		public int getX() {
			return x;
		}

		public int getY() {
			return y;
		}

		public double getDirection() {
			return direction;
		}

		public double getSpeed() {
			return speed;
		}

	}

	class MoverThread extends Thread {
		private boolean isRunning;

		public MoverThread() {
			isRunning = false;
		}

		@Override
		public void run() {
			isRunning = true;
			while (isRunning) {
				moveBalls();
				billard.repaint();
				try {
					Thread.sleep(20);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		}

		private void moveBalls() {
			for (Ball ball : balls) {
				int newX = (int) (ball.getX() + Math.cos(ball.getDirection())
						* ball.getSpeed());
				int newY = (int) (ball.getY() + Math.sin(ball.getDirection())
						* ball.getSpeed());

				if (playZone.contains(newX, newY) &&playZone.contains(newX+ballSize, newY+ballSize)) {// && playZone.contains(newX-ballSize, newY-ballSize)
					ball.setX((int) newX);
					ball.setY((int) newY);
				}else{
					//Changer la direction de la balle en focntion du bord qu'elle a touché.
					//Un bel exercice que je te laisse faire... ;-) Hacktrack
				}
			}

		}
	}

	public static void main(String[] args) {
		BillardDemo demo = new BillardDemo();
		demo.pack();
		demo.setVisible(true);
	}
}