运动的小球

[java]代码库

import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Panel;

public class pp {
	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;

	public void paint(Graphics g) {
		/*
		 * g.fillOval(30,30,20,20); int x=30; int y=30; while(true){
		 * 
		 * y++; }
		 */
		g.fillOval(x, y, 20, 30);
	}

	public void run() {
		while (true) {
			y++;
			if (y > 400) {
				y = 0;
			}
			try{
				Thread.sleep(40);
			}catch(Exception e){};
			repaint();
		}
	}

}

[代码运行效果截图]