Java 碰撞的球 MovingBall (整理)

package demo;

/**
*                     Java 碰撞的球 MovingBall (整理)
* 声明：
*     这份源代码没有注释，已经忘记了为什么要写他了，基本上应该是因为当时觉得好玩吧。
* 有时候想想，也许是因为当时就是想做一个这样的效果的东西。
*
*                                   2016-1-2 深圳 南山平山村 曾剑锋
*/

import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class MovingBall extends JPanel {

private static final long serialVersionUID = 1L;
static int centerX = 600/2;
static int centerY = 600/2;
final Ball ball = new Ball(centerX, centerY);
boolean cicleflag = true;
int cicleSemi = 0;
double angle = 0;
int ballCicle = 30;
public MovingBall() {
start();
}
@Override
public void paint(Graphics graphics) {
super.paint(graphics);
this.setBackground(Color.black);
graphics.setColor(Color.BLUE);
graphics.fillArc(centerX-cicleSemi/2, centerY-cicleSemi/2, cicleSemi, cicleSemi, 0, 360);
ball.drawing(graphics);
graphics.setColor(Color.white);
graphics.drawArc(centerX-cicleSemi/2, centerY-cicleSemi/2, cicleSemi, cicleSemi, 0, 360);
graphics.fillArc((int)(centerX+cicleSemi/2*Math.cos(angle*Math.PI/180)-ballCicle/2), (int)(centerY+cicleSemi/2*Math.sin(angle*Math.PI/180)-ballCicle/2), ballCicle, ballCicle, 0, 360);
graphics.fillArc((int)(centerX+cicleSemi/2*Math.cos((angle+180)*Math.PI/180)-ballCicle/2), (int)(centerY+cicleSemi/2*Math.sin((angle+180)*Math.PI/180)-ballCicle/2), ballCicle, ballCicle, 0, 360);
}
public void start() {
new Thread(new Runnable() {

@Override
public void run() {
while (true) {
try {
ballMove(ball);

if (cicleflag == true) {
cicleSemi += 2;
if (cicleSemi > centerX) {
cicleflag = false;
}
}else {
cicleSemi -= 2;
if (cicleSemi < 0) {
cicleflag = true;
}
}
angle ++;
repaint();
Thread.sleep(20);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}

public void ballMove(Ball ball) {
ball.x += ball.dx;
ball.y += ball.dy;
if (ball.x < 50 || ball.x > centerX*2-50) {
ball.dx = -ball.dx;
}else if (ball.y < 50 || ball.y > centerY*2-50) {
ball.dy = -ball.dy;
}
}
}).start();
}

public static void main(String[] args) {
JFrame jFrame = new JFrame();
jFrame.setTitle("MovingBall");
jFrame.setSize(centerX*2, centerY*2);
jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jFrame.setLocationRelativeTo(null);

MovingBall moveBall = new MovingBall();
jFrame.add(moveBall);
jFrame.setVisible(true);
}
}

class Ball{
static int step = 10;
int x;
int y;
int dx;
int dy;
double angle;
int cicle = 30;
public Ball(int x, int y) {
this.x = x;
this.y = y;
this.angle = Math.random()*360;
if (angle <= 180) {
dx = (int) (step*Math.cos(angle*Math.PI/180));
dy = (int) (step*Math.sin(angle*Math.PI/180));
}else {
dx = (int) (step*Math.cos(angle*Math.PI/180));
dy = -(int) (step*Math.sin(angle*Math.PI/180));
}
}
public Ball(int x, int y, int angle) {
this.x = x;
this.y = y;
this.angle = angle;
if (angle <= 180) {
dx = (int) (step*Math.cos(angle*Math.PI/180));
dy = (int) (step*Math.sin(angle*Math.PI/180));
}else {
dx = (int) (step*Math.cos(angle*Math.PI/180));
dy = -(int) (step*Math.sin(angle*Math.PI/180));
};
}
public void drawing(Graphics graphics) {
graphics.setColor(Color.white);
graphics.fillArc(this.x-cicle/2, this.y-cicle/2, cicle, cicle, 0, 360);
}
}