ピースを動かす

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class Game14 extends JPanel implements MouseListener
{
        int haba;
        int yoko, tate;
        String fname;
        Image img;
        int[][] ban;
        int spx, spy;
        
        Game14()
        {
                addMouseListener(this);
        }
        public void mousePressed(MouseEvent e)
        {
                int x, y, dx, dy;

                x = e.getX() / haba;
                y = e.getY() / haba;
                dx = (x<spx) ? -1 : (x>spx) ? 1 : 0;
                dy = (y<spy) ? -1 : (y>spy) ? 1 : 0;
//              if(x < spx)
//                      dx = -1;
//              else if(x > spx)
//                      dx = 1;
//              else
//                      dx = 0;
//              if(y < spy)
//                      dy = -1;
//              else if(y > spy)
//                      dy = 1;
//              else
//                      dy = 0;
                if(dx != 0 && dy != 0)
                        return;
                while (x != spx || y != spy)
                {
                        ban[spx][spy] = ban[spx+dx][spy+dy];
                        spx = spx + dx;
                        spy = spy + dy;
                };
                repaint();
        }
        
        public void mouseEntered(MouseEvent e) { }
        public void mouseExited(MouseEvent e) { }
        public void mouseReleased(MouseEvent e) { }
        public void mouseClicked(MouseEvent e) { }