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;
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){
x--;
y++;
}
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();
}
}
}
