java实现会反弹的小球示例

java实现简单的球的弹射，碰到墙壁就反弹一下，代码如下 

package tsct;

import java.awt.color;
import java.awt.graphics;
import java.awt.image;
import java.awt.event.windowstatelistener;
import java.io.file;
import java.io.ioexception;

import javax.imageio.imageio;
import javax.swing.jframe;

public class main extends jframe implements runnable
{
    int x=40;
    int y=30;
    int width=50;
    int height=50;
    boolean xadd=true;
    boolean yadd=true;
    public void paint(graphics g)
    {
        super.paint(g);
        //g.fillrect(x, y, width, height);
        g.setcolor(color.red);
        g.filloval(x, y, width, height);
    }
    int i=1;
    @override
    public void run()
    {
        // todo auto-generated method stub
        while(true)
        {
            if(yadd)
                y+=15;
            else
                y-=15;
            if(y>=this.getheight()-height||y<=25)
                yadd=!yadd;
            if(xadd)
                x+=30;
            else
                x-=30;
            if(x>=this.getwidth()-width||x<=5)
                xadd=!xadd;
            repaint();
            try
            {
                thread.sleep(40);
                i++;
            }
            catch (interruptedexception e)
            {
                e.printstacktrace();
            }
        }
    }
    public static void main(string[] args)
    {
//        main main=new main();
//       
//        main.setvisible(true);
//        main.run();
        main main=new main();
        main.setvisible(true);
        main.setbounds(50, 50, 800, 600);
        thread thread=new thread(main);
        thread.start();
        try
        {
            image image=imageio.read(new file(main.class.getresource("").tostring()));
        }
        catch (ioexception e)
        {
            // todo auto-generated catch block
            e.printstacktrace();
        }
    }

}