java小球撞墙代码

小球撞墙

package myball;
import java.awt.*;

public class MyBall{
	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;//0就是右下，1就是左下，2就是左上，3就是右上
	
	public void paint(Graphics g) {
		g.fillOval(x, y, 20, 20) ;
	}
	public void run() {
		while(true) {
			//定义飞行姿态
			if (att == 0) {
				x++;
				y++;
			}
			if (att == 1) {
			}
			if (att == 2) {
				x--;
				y--;
			}
			if (att == 3) {
				x++;
				y--;
			}
			//改变飞行姿态
			if (x > 263) {
				if (att == 0) {
					att = 1;
				} else {
					att = 2;
				}
			}
			if (y > 341) {
				if (att == 1) {
					att = 2;
				} else {
					att = 3;
				}
			}
			if (x < 0) {
				if (att == 2) {
					att = 3;
				} else {
					att = 0;
				}
			}
			if (y < 0) {
				if (att == 3) {
					att = 0;
				} else {
					att = 1;
				}
			}
			try {
				Thread.sleep(30) ;
			}catch(Exception e) {}
			repaint() ;
		}
	}
}