public class GameFrame extends JFrame{

private GameMenu menu;
private GameCanvas canvas;

public GameFrame(String name, int width, int height) {
        super(name);
        
        menu = new GameMenu(this, width,height);
        add(menu);
        
        canvas = new GameCanvas(width, height);

        setResizable(false);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
}

//When New Game button is pressed this metod is called.
protected void beginGame() {
        
        setContentPane(canvas);
        canvas.launchGame();
        canvas.repaint();
        validate();
}
}

public class GameCanvas extends JPanel implements KeyListener{

protected GameCanvas(int width, int height) {
        super();
        this.width = width;
        this.height = height;
        setPreferredSize(new Dimension(width, height));

        addKeyListener(this);
        setFocusable(true);
}
}