bounce.java

本程序验证java的线程技术

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import javax.swing.*;

/**
 *Shows an animated bouncing ball
 */

public class Bounce
{
	public static void main(String[] args)
	{
		JFrame frame = new BounceFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
		
	}
}

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 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;
}

class BallPanel 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>();
}

class BounceFrame extends JFrame
{
	public BounceFrame()
	{
		setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);
		setTitle("Bounce");
		
		panel = new BallPanel();
		add(panel,BorderLayout.CENTER);
		JPanel buttonPanel = new JPanel();
		addButton(buttonPanel,"Start",
			new ActionListener()
			{
				public void actionPerformed(ActionEvent event){
					addBall();
				}
			});
		addButton(buttonPanel,"Close",
			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()
	{
		try
		{
			Ball ball = new Ball();
			panel.add(ball);
			
			for(int i=0;i<STEPS;i++)
			{
				ball.move(panel.getBounds());
				panel.paint(panel.getGraphics());
				Thread.sleep(DELAY);
			}
		}catch(InterruptedException e)
		{
			
		}
	}
	
	private BallPanel panel;
	public static final int DEFAULT_WIDTH = 450;
	public static final int DEFAULT_HEIGHT = 300;
	public static final int STEPS = 1000;
	public static final int DELAY = 3;
}