Java | 小球碰撞

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import javax.swing.*;

public class Main extends JFrame {
//主程序
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				JFrame frame = new BounceFrame();
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
			}
		});
	}
}

//小球弹跳
class BallRunable implements Runnable {
	public BallRunable(Ball aBall, Component aComponent) {
		ball = aBall;
		component = aComponent;
	}

	public void run() {
		try {
			for (int i = 1; i <= STEPTS; i++) {
				ball.move(component.getBounds());
				component.repaint();
				Thread.sleep(DELAY);
			}
		} catch (InterruptedException e) {
		}
	}

	private Ball ball;
	private Component component;
	public static final int STEPTS = 1000;
	public static final int DELAY = 5;
}

//定义窗体
class BounceFrame extends JFrame {
	public BounceFrame() {
		setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
		setTitle("MoveBall");
		comp = new BallComponent();
		add(comp, BorderLayout.CENTER);
		JPanel buttonPanel = new JPanel();
		addButton(buttonPanel, "开始", new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				addBall();
			}
		});
		addButton(buttonPanel, "结束", new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				System.exit(0);
			}
		});
		add(buttonPanel, BorderLayout.SOUTH);
	}

	public void addButton(Container c, String title, ActionListener listener) {
		JButton button = new JButton(title);
		c.add(button);
		button.addActionListener(listener);
	}

	public void addBall() {
		Ball b = new Ball();
		comp.add(b);
		Runnable r = new BallRunable(b, comp);
		Thread t = new Thread(r);
		t.start();
	}

	private BallComponent comp;
	public static final int DEFAULT_WIDTH = 450;
	public static final int DEFAULT_HEIGHT = 350;
	public static final int STEPS = 1000;
	public static final int DELAY = 3;
}

//定义小球
class Ball {
	public void move(Rectangle2D bounds) {
		x += dx;
		y += dy;
		if (x < bounds.getMinX()) {
			x = bounds.getMinX();
			dx = -dx;
		}
		if (x + XSIZE >= bounds.getMaxX()) {
			x = bounds.getMaxX() - XSIZE;
			dx = -dx;
		}
		if (y < bounds.getMinY()) {
			y = bounds.getMinY();
			dy = -dy;
		}
		if (y + YSIZE >= bounds.getMaxY()) {
			y = bounds.getMaxY() - YSIZE;
			dy = -dy;
		}
	}

	public void move(Component component, Object bounds) {
// TODO Auto-generated method stub
	}

	public Ellipse2D getShape() {
		return new Ellipse2D.Double(x, y, XSIZE, YSIZE);
	}

	private static final int XSIZE = 15;
	private static final int YSIZE = 15;
	private double x = 0;
	private double y = 0;
	private double dx = 1;
	private double dy = 1;
}

//定义小球显示窗体
class BallComponent extends JPanel {
	public void add(Ball b) {
		balls.add(b);
	}

	public void paintComponent(Graphics g) {
		super.paintComponent(g);
		Graphics2D g2 = (Graphics2D) g;
		for (Ball b : balls) {
			g2.fill(b.getShape());
		}
	}

	private ArrayList<Ball> balls = new ArrayList<Ball>();
}