小球怎么一直循环啊!

[zhoujg77]

import java.awt.*;
import java.lang.Thread;

public class Test2 {

	public static void main(String[] args) {
		Frame w = new Frame();
		w.setSize(300, 400);
		MyPanel mp = new MyPanel();
		w.add(mp);

		Thread t = new Thread(mp);
		t.start();

		w.show();

	}

}

class MyPanel extends Panel implements Runnable {
	int x = 30;
	int y = 30;
	int att=0;
	public void paint(Graphics g) {

		g.fillOval(x, y, 20, 20);

	}

	public void run() {

		while (true) {
			
				
				x++;y++;			
				

					
			
			try {
				Thread.sleep(30);
			} catch (Exception e) {
			}
			repaint();

		}

	}

}

怎么能让求一直循环撞墙啊！

[jiabiaoli]

小球每移动一次 都要判断一次 x,y 点 是否在 窗口内部, 首先定义两个变量,初始值xpath=1;yPath=1; x的下一个点的位置在x+=xPath; 若x的值超过窗口右侧,则xPath=-1; x+=xPath; 同理 y+=yPath;

private int xPath=1;
    private int yPath=1;
    public void run() {
 
        while (true) {
        	if(x<0){
        		xPath=1;
        	}
        	if(x>265){
        		xPath=-1;
        	}
        	x+=xPath;
        	if(y<0){
        		yPath=1;
        	}
        	if(y>350){
        		yPath=-1;
        	}
        	y+=yPath;
            try {
                Thread.sleep(10);
            } catch (Exception e) {
            }
            repaint();
 
        }
 
    }

[lliiqiang]

撞到墙就往回返到原点再撞墙.

[zhoujg77]

自己顶一下！书上用4种状态表示球的路线（右下，左下，左上，右上）完全看不懂啊！