Digital Clock

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

class Clock extends JFrame implements Runnable
{
  Thread runner; //declare global objects
  Font clockFont;

     public Clock()
     {
       super("Java clock");
       setSize( 350, 100);
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       setVisible(true);
       setResizable(false);                             //create window

       clockFont = new Font("Serif", Font.BOLD, 40);    //create font instance

       Container contentArea = getContentPane();
       ClockPanel timeDisplay = new ClockPanel();


       contentArea.add(timeDisplay);                    //add components
       setContentPane(contentArea);
       start();                                         //start thread running

     }


     class ClockPanel extends JPanel
     {
      public void paintComponent(Graphics painter )
        {
        Image pic =
          Toolkit.getDefaultToolkit().getImage("background.jpg");

         if(pic != null)

            painter.drawImage(pic, 0, 0, this);     //create image


//if I didn't use a background image I would have used the setColor and fillRect methods to set background

          painter.setFont(clockFont);                   //create clock components
          painter.setColor(Color.black);
          painter.drawString( timeNow(), 60, 40);


        }
     }


     //get current time
     public String timeNow()
     {
       Calendar now = Calendar.getInstance();
       int hrs = now.get(Calendar.HOUR_OF_DAY);
       int min = now.get(Calendar.MINUTE);
       int sec = now.get(Calendar.SECOND);

       String time = zero(hrs)+":"+zero(min)+":"+zero(sec);

       return time;
     }



     public String zero(int num)
     {
       String number=( num < 10) ? ("0"+num) : (""+num);
       return number;                                    //Add leading zero if needed

     }


     public void start()
     {
       if(runner == null) runner = new Thread(this);
       runner.start();
                                                             //method to start thread
     }


     public void run()
     {
       while (runner == Thread.currentThread() )
       {
        repaint();
                                                         //define thread task
           try
             {
               Thread.sleep(1000);
             }
              catch(InterruptedException e)
                  {
                    System.out.println("Thread failed");
                  }

       }
     }

     //create main method
     public static void main(String [] args)
     {
       Clock eg = new Clock();
     }
}