博客

package 桌球;

import java.awt.

;

import javax.swing.

;

public class BallGame extends JFrame{

Image ball = Toolkit.getDefaultToolkit().getImage("images/ball.png");
Image desk = Toolkit.getDefaultToolkit().getImage("images/desk.jpg");
double x = 100;
double y = 100;
//boolean right = true;//right 向右
double degree = 3.14/3;//弧度,此处就是60度;degree度数

//图片加载
public void paint(Graphics g){
	System.out.println("刷新");
	g.drawImage(desk, 0, 0, null);
	g.drawImage(ball,(int) x, (int)y, null);//球的位置//出现报错,强制类型转换
	
	//直线运动
	/*if(right){
		x = x +10;
	}else{
		x = x - 10;
	}
	
	if(x>650){
		right = false;
		//x = x - 10;
	}
	if(x<40){
		right = true;	
	}*/
	//变换角度
	x = x + 5*Math.cos(degree);
	y = y + 5*Math.sin(degree);
	//上下边界
	if(y>421-35-30||y<35+20){//421窗口高度,30是桌子边框,30球的直径;30+20是桌子边框 加上上面标题栏的宽度
		degree = -degree;
		
	}
	//左右边界
	if(x