java语言的科学与艺术-编程练习4.15

画一个不停反弹的小球。

 1 /*
 2  * File:BouncingBall.java
 3  * -------------------
 4  * This program draw a bouncing ball.
 5  */
 6 
 7 import acm.program.*;
 8 import acm.graphics.*;
 9 import java.awt.*;
10 
11 public class BouncingBall extends GraphicsProgram {
12     
13     public void run(){
14         int x = (getWidth() - DIAMETER) / 2;
15         int y = (getHeight() - DIAMETER) / 2;
16         GOval ball = new GOval(x, y,DIAMETER, DIAMETER);
17         ball.setFilled(true);
18         add(ball);
19         int dx = 1;
20         int dy = 1;
21         while(true){
22             ball.move(dx, dy);
23             pause(PAUSE_TIME);
24             x += dx;
25             y += dy;
26             if(x > getWidth() - DIAMETER || x < 0) dx = -dx;
27             if(y > getHeight() - DIAMETER || y < 0) dy = -dy;
28         }
29     }
30     /* Private constants */
31     private static final int DIAMETER = 40;
32     private static final int PAUSE_TIME = 20;
33     
34 }

 

posted on 2012-12-06 22:42  mybluecode  阅读(218)  评论(0)  编辑  收藏  举报