creating a frame with four clocks

[Programming sta]

I am trying to develop an application that can display four clocks in a frame that update at the following intervals: 1 second, 5 seconds, 30 seconds and 60 seconds, here is the code so far.

Timer.java
import javax.swing.*;

public class Timer extends Thread {
    private int waitTime;
    private JPanel panel;
    private boolean active = true;

    public Timer (int waitTime, JPanel panel) {
        /** Correct the two lines of code below **/
        waitTime = waitTime;
        panel = panel;
    }

    // Overridden run method. Will keep looping until active is false
    public void run () {
        while (active) {
            try {
                sleep(waitTime);
            }
            catch (InterruptedException e) {
            // any exceptions will be caught but ignored
            }
        panel.repaint();    // Force panel to be redrawn
        }
    }
    public void stopTimer() {
        active = false;
    }
}

ClockPanel.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.Date;
import java.text.SimpleDateFormat;

public class ClockPanel extends JPanel {
    private static int  WIDTH  = 500;
    private static int  HEIGHT = 200;

    static final SimpleDateFormat formatter
                           = new SimpleDateFormat ("HH:mm:ss");

    public ClockPanel (int milli) {
        //
       // Create and start a new thread
       this.setBorder(BorderFactory.createLineBorder(Color.white));
       Timer timer = new Timer (milli, this);
       timer.start();
    }

    public static void main (final String[] args ) {

        JFrame clockFrame = new JFrame ("Clock");
        JPanel mainPanel  = new JPanel (new GridLayout(2,2));

        clockFrame.getContentPane().add(mainPanel);
        mainPanel.setPreferredSize(new Dimension(WIDTH, HEIGHT));

        ClockPanel p1 = new ClockPanel(1000);
        /** create additional ClockPanel objects **/

        /** add the individual ClockPanel objects to the main panel **/

        clockFrame.pack ();
        clockFrame.setVisible(true);
        clockFrame.addWindowListener( new WindowAdapter() {
            public void windowClosing(WindowEvent e) {  
            System.exit(0); } } );
       }

    public void paint (final Graphics g) {
        super.paint(g);         // Clear the panel
        Font big = new Font("Serif", Font.PLAIN, 40);
        g.setFont(big);

        // Provide the parameters to the drawstring method below
        g.drawString(...............);
    }
}