import java.awt.*;

import java.awt.event.*;

class Marble extends Thread

{

Table table=null;

int x,y,xdir,ydir;

public Marble (Table _table,int _x,int _y,int _xdir,int _ydir)

{

table=_table;

x=_x;

y=_y;

xdir=_xdir;

ydir=_ydir;

}

public void run()

{

while(true)

{

if((x>(table.getSize().width)-25)||(x<0))

{

xdir*=(-1);

}

if((y>(table.getSize().width)-25)||(y<0))

{

ydir*=(-1);

}

x+=xdir;

y+=ydir;

try

{

sleep(30);

}

catch(InterruptedException e)

{

System.err.println("Thread iterrupted");

}

table.repaint();

}

}

public void draw(Graphics g)

{

g.setColor(Color.black);

g.fillOval(x, y, 30, 30);

g.setColor(Color.white);

g.fillOval(x+5,y+5,8,6);

}

}

class Table extends Frame implements ActionListener

{

Button start=new Button("start");

Marble marbles[]=new Marble[5];

int v=2;

public Table()

{

super("弹子弹球");

setSize(300,300);

setBackground(Color.cyan);

setVisible(true);

setLayout(new FlowLayout());

add(start);

start.addActionListener(this);

validate();

addWindowListener(new WindowAdapter()

{

public void windowClosing(WindowEvent e)

{

System.exit(0);

}

});

}

public void actionPerformed(ActionEvent arg0) {

// TODO Auto-generated method stub

for(int i=0;i<marbles.length;i++)

{

int xdir=i*(1-i*(int)Math.round(Math.random()))+v;

int ydir=i*(1-i*(int)Math.round(Math.random()))+v;

int x=(int)(getSize().width*Math.random());

int y=(int)(getSize().width*Math.random());

marbles[i]=new Marble(this,x,y,xdir,ydir);

marbles[i].start();

}

}

public void paint(Graphics g)

{

for(int i=0;i<marbles.length;i++)

{

if(marbles[i]!=null)

{

marbles[i].draw(g);

}

}

}

}

public class Main {

public static void main(String args[])

{

Table table=new Table();

}

}