Draughts Game.

Hi,
I am creating a draughts game. I have the board set up, with opposing pieces created using a 2D array of type player (player 1 and player 2) and size 8*8. Each piece is therefore an object of the player class.
I am unsure how to king a piece. By using a piece class, i have set up my four types of piece relating to the appropriate player (eg - WHITE_PIECE, WHITE_KING for player1). I need to find out how to upgrade a player's single piece when it needs crowned.
Thanks.

In your other thread that you had posted earlier we had discussed the flaws in your design.
Object oriented isn't just a methodology we follow because we are told to. It truly is there to help make designing an application easier and more intuitive and organized.
When you design your classes, think in terms of objects in real life... What are your fundamental objects in a game of Checkers (Draughts for your Euro weenies)?
A Player, has a name, has a color distinction, white or black player.
A Game, keeps track of whose turn, has two Players, has a Board, has behavior to cofirm if one player has won the game.
A Board, has 64 Squares, has Checkers, has game logic that determines legal moves, checks for a King condition on a Checker, behavior to remove a piece if it got jumped, determines if a player can make multiple jumps, other game logic...
A Square, is either white or black, has a Checker or not
A Checker, is either white or black, has a flag for whether or not it is a King.
I think you get the point. This is just to get you started but you should write this rough design down then possibly draw a class diagram with the information you have. Be thorough and complete, you should have enough detail to where all the manageable peices of the code are broken down to simple coding tasks.
We have told you this once before that you are causing yourself a lot of grief trying to get this game to work with your current design.

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I want to repaint the canvas panel in this bouncing balls game, but i do something wrong i don't know what, and the JPanel doesn't repaint?
The first class defines a BALL as a THREAD
If anyone knows how to correct the code please to write....
package fuck;
//THE FIRST CLASS
class CollideBall extends Thread{
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    Rectangle r;
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        height=h;
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        this.y=y;
        this.xinc=xinc;
        this.yinc=yinc;
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    public double getCenterY() {return y+diameter/2;}
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        y+=yinc;
        //when the ball bumps against a boundary, it bounces off
        //bounce off the obstacle
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        if(!collide) {
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            coll_y=b.getCenterY();
            collide=true;
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        Graphics g = gr;
        g.setColor(color);
        //the coordinates in fillOval have to be int, so we cast
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public class BouncingBalls extends JFrame{
    public Graphics gBuffer;
    public BufferedImage buffer;
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    private List<CollideBall> balls=new ArrayList();
    private static final int SPEED_MIN = 0;
    private static final int SPEED_MAX = 15;
    private static final int SPEED_INIT = 3;
    private static final int INIT_X = 30;
    private static final int INIT_Y = 30;
    private JSlider slider;
    private ChangeListener listener;
    private MouseListener mlistener;
    private int speedToSet = SPEED_INIT;
    public JPanel canvas;
    private JPanel p;
    public BouncingBalls() {
        super("fuck");
        setSize(800, 600);
        p = new JPanel();
        Container contentPane = getContentPane();
        final BouncingBalls xxxx=this;
        o=new Obstacle(150,80,130,90);
        buffer=new BufferedImage(getSize().width, getSize().height, BufferedImage.TYPE_INT_RGB);
        gBuffer=buffer.getGraphics();
        //JPanel canvas start
        final JPanel canvas = new JPanel() {
            final int w=getSize().width-5;
            final int h=getSize().height-5;
            @Override
            public void update(Graphics g)
               paintComponent(g);
            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                gBuffer.setColor(Color.ORANGE);
                gBuffer.fillRect(0,0,getSize().width,getSize().height);
                gBuffer.draw3DRect(5,5,getSize().width-10,getSize().height-10,false);
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                g.drawImage(buffer,0,0, null);
                //gBuffer.dispose();
        };//JPanel canvas end
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            @Override
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                System.exit(0);
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        double wx=b1.getCenterX()-b2.getCenterX();
        double wy=b1.getCenterY()-b2.getCenterY();
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        if(distance<b1.diameter)
            return true;
        return false;
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        for (CollideBall x:balls) if (x!=a && collide(x,a)) {
            x.hit(a);
            a.hit(x);
    public static void main(String[] args) {
        JFrame frame = new BouncingBalls();
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} And when i press start button:
Exception in thread "Thread-2" java.lang.NullPointerException
at fuck.CollideBall.run(CollideBall.java:153)
Exception in thread "Thread-3" java.lang.NullPointerException
at fuck.CollideBall.run(CollideBall.java:153)
Exception in thread "Thread-4" java.lang.NullPointerException
at fuck.CollideBall.run(CollideBall.java:153)
and line 153 is: balls.canvas.repaint(); in Method run() in First class.
Please help.

public RepaintManager manager;
public BouncingBalls() {
        manager = new RepaintManager();
        manager.addDirtyRegion(canvas, 0, 0,canvas.getSize().width, canvas.getSize().height);
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        while(true) {
            try {Thread.sleep(15);} catch (Exception e) { }
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Exception in thread "Thread-2" java.lang.IllegalMonitorStateException
at java.lang.Object.notifyAll(Native Method)
at fuck.CollideBall.run(CollideBall.java:153)
Exception in thread "Thread-3" java.lang.IllegalMonitorStateException
at java.lang.Object.notifyAll(Native Method)
at fuck.CollideBall.run(CollideBall.java:153)
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I want to repaint the canvas panel in this bouncing balls game, but i do something wrong i don't know what, and the JPanel doesn't repaint?
The first class defines a BALL as a THREAD
If anyone knows how to correct the code please to write....
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            final int h=getSize().height-5;
            @Override
            public void update(Graphics g)
               paintComponent(g);
            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
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                gBuffer.fillRect(0,0,getSize().width,getSize().height);
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                //gBuffer.dispose();
        };//JPanel canvas end
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            @Override
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        double wy=b1.getCenterY()-b2.getCenterY();
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} This code draws only the first position of the ball:
http://img267.imageshack.us/my.php?image=51649094by6.jpg

I'm trying to draw everything first to a buffer:
buffer=new BufferedImage(getSize().width, getSize().height, BufferedImage.TYPE_INT_RGB);
gBuffer=buffer.getGraphics();
The buffer is for one JPanel and then i want to draw this buffer every time when balls change their possitions(collide or just move).
The logic is something like this:
startButton -> (ball.start() and add ball to List<balls>),
ball.start() -> ball.run() -> (move allballs, paint to buffer and show buffer)
In the first class:
BouncingBalls balls; //A REFERENCE TO SECOND CLASS
In the second class:
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the tames are the same but this isn't an error.
Edited by: vigour on Feb 14, 2008 7:57 AM

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