碰壁的小球（原代码转载）

原代码转载于https://www.136.la/java/show-45068.html

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Panel;

import javax.swing.JFrame;

public class Ball {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        JFrame win=new JFrame();//新建窗口
        win.setLocation(250,100);//设置窗口位置
        win.setSize(800,600);//设置窗口大小
        win.show();//显示窗口
        win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置关闭退出
        AAAA my=new AAAA();
        win.add(my);
        Thread t=new Thread(my);
        t.start();
    }
}

class AAAA extends Panel implements Runnable{
    int x=0,y=0;
    int flyx=1,flyy=1;
    public void paint(Graphics g) {
        g.setColor(Color.yellow);
        g.fillOval(x, y, 70, 70);
// System.out.println("23");
        if (flyx==1) {
            x++;
        }
        if(flyx ==2) {
            x--;
        }
        if(flyy==1) {
            y++;
        }
        if(flyy==2) {
            y--;
        }
        if(x>730) {
            flyx=2;
        }
        if(x<0) {
            flyx=1;
        }
        if(y<0) {
            flyy=1;
        }
        if(y>530) {
            flyy=2;
        }
    }
    public void run() {
        while(true){
            repaint();
            try {

                Thread.sleep(10);
            }
            catch(Exception e) {

            }
        }
    }
}