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);
     }
 }

效果如图：