A problem in my PONG game code

[max wang]

 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.Timer;
 
 
public class MyPong extends JFrame implements KeyListener,ActionListener
{
 static int table_width =500;
     static int table_height =500;
     
     static int paddle_x=100;
     static int paddle_y=30;
     static int paddle_w=20;
     static int paddle_h=300;
     
     static int ball_x=100; //original x,y
     static int ball_y=350; 
     static int ball_w=40;
     static int ball_h=40;
     
     static int hit=0;
     static int misses=0;
     
     int ball_speed=10;
     int delta_x=ball_speed;
     int delta_y=ball_speed;
     
     //define all edge, move ball by only ball_x,ball_y
     int paddle_x_edge = paddle_x + paddle_w;
     int top_edge = 0;
     int bottom_edge = table_height-ball_h; //bottom net-margin
     int right_edge = table_width - ball_w; //right net-margin
     
     
     //define Timer,DrawPanel
     Timer t;
     DrawPanel dp=new DrawPanel();
     String title;
           
       
    public MyPong()
    {
       
       add(dp);
       addKeyListener(this);
       setFocusable(true);
       
       t = new Timer(500,this);
       t.start();
       
 
    }
    
    
 
        class DrawPanel extends JPanel 
        {
       public void paintComponent(Graphics g) 
           {
              super.paintComponent(g);  //clear
         
              g.drawRect(paddle_x,paddle_y,paddle_w,paddle_h);   //draw paddle
      
              g.drawOval(ball_x,ball_y,ball_w,ball_h);      //draw ball
        
            }
              
        }//end DrawPanel
    
    
           public void actionPerformed(ActionEvent e)
           {
              ball_x+=delta_x;
        ball_y+=delta_y;  
        
        if(ball_x>right_edge) delta_x*=-1;
        
        else if (ball_y>bottom_edge || ball_y<top_edge)
        {
        delta_y*=-1;
        }
 
        else if (ball_x==paddle_x_edge && ball_y>paddle_y 
                           && ball_y<(paddle_y+paddle_h)) 
        {
        delta_x*=-1;
        hit+=1;
        System.out.println("Hit="+hit);
                           
        }
        else if(ball_x<paddle_x && ball_x>0)
        {
        
        ball_w=(int)(ball_w/2);
        ball_h=(int)(ball_h/2);
        
        }
        else if (ball_x==0)
        {
        delta_x*=-1;
        misses+=1;
        System.out.println("Misses="+misses);
                
                        
        ball_x=100; //original x,y
                ball_y=350; 
        
          ball_w=40;
                ball_h=40;
        
        }
              dp.repaint();
      
        }//end actionPerformed
    
 
    
        //----------implement KeyListener-----------
        public void keyReleased(KeyEvent ke){}
    public void keyTyped(KeyEvent ke){}
    
    public void keyPressed(KeyEvent ke)
    {
    int k=ke.getKeyCode();
    if(k==KeyEvent.VK_DOWN) paddle_y+=50;
    else if(k==KeyEvent.VK_UP) paddle_y-=50;
    
    dp.repaint();
     }
 
       
 
    
        
    //-----------main method------------------------------------ 
    public static void main(String[] args)
     {
     MyPong mp = new MyPong(); // Create the frame 
              
      mp.setSize(mp.table_width,mp.table_height);   
mp.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
      mp.setTitle("Pong Demo"+"hit="+hit+"misses:"+misses); 
      mp.setVisible(true); 
     
    } 
    
    
}//end main class
 
 

I change the code, PONG game works. But there is a new problem, the hit score and misses score must show in the title bar of frame. mp.setTitle("Pong Demo"+"hit="+hit+"misses:"+misses); cannot show the score. The problem is that I cannot send the hit and misses variable to the frames. when they change.

[ May 27, 2008: Message edited by: max wang ]
[ May 27, 2008: Message edited by: max wang ]

[Darryl Burke]

Comments:

Key events are received only by the focus owner, for this kind of application you would be better served by using key bindings.
The Java Tutorials: How to Use Key Bindings.

What key listener do you add to DrawPanel dp? Did you really mean to add a new KeyCnt()? What is the code in that class? since you didn't post it.

At two places in the code posted, you have else without if. The purpose of posting code is defeated if the code posted has syntax errors. (except where the problem is the syntax error)

And when all else is sorted out, you're going to discover that the down arrow moves the paddle up and vice versa

[max wang]

Darryl , I made a mistake on post in stead of the source code. I try to fix according to your comment. Thanks