Java两球碰撞小程序

两球相撞程序如下：

     public class Draw {
     public static void main(String[] args){
    JFrame frame=new JFrame();
    frame.setSize(1024,768);    
    Color bgColor=Color.BLACK;
    frame.setBackground(bgColor);
    Ball w=new Ball();
    frame.add(w);
    frame.getContentPane().setBackground(Color.white);
    
    Thread t=new Thread(w);
    t.start();
    
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}}
    class Ball extends Panel implements Runnable{   
      int y1=0,x1=0,y2=((int)(Math.random()*500))+200,x2=((int)(Math.random()*800))+200;
      int i=10,j=110,z=10,i2=0,j2=100,z2=0;
      int X1_juge=1,Y1_juge=1,X1_temp=1,Y1_temp=1;
      int X2_juge=1,Y2_juge=1,X2_temp=1,Y2_temp=1;
     //X_juge判断小球水平方向是否撞墙，Y_juge判断竖直方向是否撞墙,temp判 断juge是否变化
      Color colo=new Color(i, j, z);
      Color colo2=new Color(i2,j2,z2);
      public void paint(Graphics g){
      if(X1_temp!=X1_juge)  //当小球水平撞墙后给该小球随机取颜色，并将temp=juge
      {
        i=(int)(Math.random()*100);
        j=(int)(Math.random()*100);
        z=(int)(Math.random()*100);
        X1_temp=X1_juge;
      }
    if(Y1_temp==Y1_juge) ;
    else
    {
    i=(int)(Math.random()*100);
    j=(int)(Math.random()*100);
    z=(int)(Math.random()*100);
    Y1_temp=Y1_juge;
    }
    colo=new Color(i,j,z);
    g.setColor(colo);
    //g.setFont(new Font("",0,30));
    g.fillOval(x1, y1, 20, 20);
    if(!(X2_temp==X2_juge))
    {
        i2=(int)(Math.random()*100);
        j2=(int)(Math.random()*100);
        z2=(int)(Math.random()*100);
        X2_temp=X2_juge;
        }
    if(Y2_temp==Y2_juge) ;
    else
    {i2=(int)(Math.random()*100);
    j2=(int)(Math.random()*100);
    z2=(int)(Math.random()*100);
    Y2_temp=Y2_juge;
    }
    colo2=new Color(i2,j2,z2);
    g.setColor(colo2);
    g.fillOval(x2, y2, 20, 20);
    }
public void run()
{
    while(true)
    {
        if(X1_juge==1&&Y1_juge==1){
            y1++;
            x1++;
            if(x1>1000) X1_juge=0;  //当小球撞墙时juge变化
            if(y1>720) Y1_juge=0;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();  
        }
        else if(X1_juge!=1&&Y1_juge==1)
        {
            y1++;x1--;
            if(x1<10) X1_juge=1;
            if(y1>720) Y1_juge=0;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        else if(X1_juge==1&&Y1_juge!=1){
            x1++;
            y1--;
            if(x1>1000) X1_juge=0;
            if(y1<10) Y1_juge=1;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        else{
            x1--;
            y1--;
            if(x1<10) X1_juge=1;
            if(y1<10) Y1_juge=1;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        if(Math.abs(x1-x2)<=20&&Math.abs(y1-y2)<=20){ 
            //当两小球球心间距小于等于20时判定相撞
            if(X1_juge==0) X1_juge=1;
            else X1_juge=0;
            if(Y1_juge==0) Y1_juge=1;
            else Y1_juge=0;
            if(X2_juge==0) X2_juge=1;
            else X2_juge=0;
            if(Y2_juge==0) Y2_juge=1;
            else Y2_juge=0;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        if(X2_juge==1&&Y2_juge==1){
            y2--;
            x2--;
            if(x2<10) X2_juge=0;
            if(y2<10) Y2_juge=0;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();  
        }
        else if(X2_juge!=1&&Y2_juge==1)
        {
            y2--;x2++;
            if(x2>1000) X2_juge=1;
            if(y2<10) Y2_juge=0;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        else if(X2_juge==1&&Y2_juge!=1){
            x2--;
            y2++;
            if(x2<10) X2_juge=0;
            if(y2>720) Y2_juge=1;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();
        }
        else{
            x2++;
            y2++;
            if(x2>1000) X2_juge=1;
            if(y2>720) Y2_juge=1;
            try{
                Thread.sleep(5);
            }catch(Exception ex){}
            repaint();}}}}