import javax.swing.*;  
      
    import java.awt.*;  
      
    import java.util.Date;  
      
    public class SimpleDigitalClock extends JPanel  
    {  
    JFrame frame;  
      
    int currentHour;  
    int currentMinute;  
    int currentSecond;  
      
    //Font that will be use to show digital clock  
    Font myFont=new Font("Tahoma",Font.BOLD+Font.ITALIC,20);  
      
    //Color that will be use to show digital clock  
    Color myColor=new Color(255,0,0);  
      
    //Font metrics that will use to store font informations  
    //For example, width of a character  
    FontMetrics fm;  
      
    public SimpleDigitalClock()  
    {  
    //Create a window using JFrame with title ( Simple Digital Clock )  
    frame=new JFrame("Simple Digital Clock");  
      
    //add(this) mean add created panel into JFrame  
    //Which panel ?  
    //See line 81 and 7 (I hope you understand it)  
    frame.add(this);  
      
    //Set default close operation for JFrame  
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
      
    //Set JFrame size  
    frame.setSize(300,300);  
      
    //Make JFrame locate at center  
    frame.setLocationRelativeTo(null);  
      
    //Make JFrame visible  
    frame.setVisible(true);  
      
    /* 
     *Loop that will make sure panel show current time 
     *like current second, current minute and current hour. 
     */  
    while(true)  
    {  
     //It will do all code in method paint(See line 67)  
     repaint();  
      
     try  
     {  
      Thread.sleep(900);  
     }  
     catch(Exception exception)  
     {  
      exception.printStackTrace();  
     }  
    }  
    }  
      
    public void paint(Graphics g)  
    {  
    super.paint(g);  
      
    /* 
     *Create  current Date object. It means it store information 
     *about current hour, minute and second. 
     */  
    Date myDate=new Date();  
      
    currentHour=myDate.getHours();  
    currentMinute=myDate.getMinutes();  
    currentSecond=myDate.getSeconds();  
      
    //Set font that will use to draw digital number  
    g.setFont(myFont);  
      
    //Information about distance between number in digital clock  
    fm=g.getFontMetrics();  
    int hourXCoordinate=20;  
    int minuteXCoordinate=hourXCoordinate+(fm.getMaxAdvance()*2);  
    int secondXCoordinate=hourXCoordinate+(fm.getMaxAdvance()*4);  
      
    //Set color that will use to draw digital number  
    g.setColor(myColor);  
      
    //Draw hour, draw (:) between number, draw minute and draw second.  
    g.drawString(Integer.toString(currentHour),hourXCoordinate,20);  
    g.drawString(":",(hourXCoordinate+minuteXCoordinate)/2,20);  
    g.drawString(Integer.toString(currentMinute),minuteXCoordinate,20);  
    g.drawString(":",(secondXCoordinate+minuteXCoordinate)/2,20);  
    g.drawString(Integer.toString(currentSecond),secondXCoordinate,20);  
    }  
      
    public static void main(String[]args)  
    {  
    SimpleDigitalClock sdc=new SimpleDigitalClock();  
    }  
    }