Need help writing Java Code .

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JButton;

import java.awt.BorderLayout;

import java.awt.FlowLayout;

import java.awt.Graphics;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

public class ThreadedFillDemo extends JFrame implements ActionListener

{

public static final int WIDTH = 300;

public static final int HEIGHT = 200;

public static final int FILL_WIDTH = 300;

public static final int FILL_HEIGHT = 100;

public static final int CIRCLE_SIZE = 10;

public static final int PAUSE = 100; //milliseconds

private JPanel box;

public static void main(String[] args)

{

ThreadedFillDemo gui = new ThreadedFillDemo( );

gui.setVisible(true);

}

public ThreadedFillDemo( )

{

setSize(WIDTH, HEIGHT);

setTitle("Threaded Fill Demo");

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setLayout(new BorderLayout( ));

box = new JPanel( );

add(box, BorderLayout.CENTER);

JPanel buttonPanel = new JPanel( );

buttonPanel.setLayout(new FlowLayout( ));

JButton startButton = new JButton("Start");

startButton.addActionListener(this);

buttonPanel.add(startButton);

add(buttonPanel, BorderLayout.SOUTH);

}

public void actionPerformed(ActionEvent e)

{

Packer packerThread = new Packer( );

packerThread.start( );

}

private class Packer extends Thread

{

public void run( )

{

Graphics g = box.getGraphics( );

for (int y = 0; y

for (int x = 0; x

{

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

doNothing(PAUSE);

}

}

public void doNothing(int milliseconds)

{

try

{

Thread.sleep(milliseconds);

}

catch(InterruptedException e)

{

System.out.println("Unexpected interrupt");

System.exit(0);

}

}

} //End Packer inner class

}

Write a GUI program that uses the methods in the Graphics class together with the threads to draw a smiley face, wait two seconds, draw a frowny face, wait two seconds, and repeat starting with the smiley face. A separate thread should be started to implement the two-second timer. The application should be responsive and exit immediately if the user decides to close the window