Analog Clock Design in Java

Clock.java

/*
An analogue clock using the Graphics class in Java
*/

/*
Author: Sayantan Paul
Regd. No: 1841012233 
CSE-E
*/

import java.awt.Color;  
import java.awt.Font;  
import java.awt.Graphics;  
import java.text.SimpleDateFormat;  
import java.util.Date;  
import java.util.Locale;  
import javax.swing.JFrame;  
import javax.swing.JPanel;  

public class Clock extends JPanel implements Runnable {

    private static final long serialVersionUID = 4437537507102971782L;

    Thread thread = null;
    SimpleDateFormat formatter = new SimpleDateFormat("s", Locale.getDefault());  
    Date currentDate;  
    int xcenter = 175, ycenter = 175, lastxs = 0, lastys = 0, lastxm = 0, lastym = 0, lastxh = 0, lastyh = 0;  
    
    private void drawStructure(Graphics g) {  
        g.setFont(new Font("Arial", Font.BOLD, 20));  
        g.setColor(Color.black);  
        g.fillOval(xcenter - 150, ycenter - 150, 300, 300);  
        g.setColor(Color.blue);  
        g.drawString("Analog Clock", 113, 300);  
        g.setColor(Color.green);  
        g.drawString("9", xcenter - 145, ycenter + 0);  
        g.drawString("3", xcenter + 135, ycenter + 0);  
        g.drawString("12", xcenter - 10, ycenter - 130);  
        g.drawString("6", xcenter - 10, ycenter + 145);  
    }

    public void paint(Graphics g) {  
        
        int xhour, yhour, xminute, yminute, xsecond, ysecond, second, minute, hour;  
        drawStructure(g);  
        currentDate = new Date();  
        
        formatter.applyPattern("s");  
        second = Integer.parseInt(formatter.format(currentDate));  
        formatter.applyPattern("m");  
        minute = Integer.parseInt(formatter.format(currentDate));  
        formatter.applyPattern("h");  
        hour = Integer.parseInt(formatter.format(currentDate));  
        
        xsecond = (int)(Math.cos(second * 3.14f / 30 - 3.14f / 2) * 120 + xcenter);  
        ysecond = (int)(Math.sin(second * 3.14f / 30 - 3.14f / 2) * 120 + ycenter);  
        xminute = (int)(Math.cos(minute * 3.14f / 30 - 3.14f / 2) * 100 + xcenter);  
        yminute = (int)(Math.sin(minute * 3.14f / 30 - 3.14f / 2) * 100 + ycenter);  
        xhour = (int)(Math.cos((hour * 30 + minute / 2) * 3.14f / 180 - 3.14f / 2) * 80 + xcenter);  
        yhour = (int)(Math.sin((hour * 30 + minute / 2) * 3.14f / 180 - 3.14f / 2) * 80 + ycenter);  
         
        g.setColor(Color.magenta);  
        if (xsecond != lastxs || ysecond != lastys) {  
            g.drawLine(xcenter, ycenter, lastxs, lastys);  
        }  
        if (xminute != lastxm || yminute != lastym) {  
            g.drawLine(xcenter, ycenter - 1, lastxm, lastym);  
            g.drawLine(xcenter - 1, ycenter, lastxm, lastym);  
        }  
        if (xhour != lastxh || yhour != lastyh) {  
            g.drawLine(xcenter, ycenter - 1, lastxh, lastyh);  
            g.drawLine(xcenter - 1, ycenter, lastxh, lastyh);  
        }

        g.setColor(Color.magenta);  
        g.drawLine(xcenter, ycenter, xsecond, ysecond);  
        g.setColor(Color.red);  
        g.drawLine(xcenter, ycenter - 1, xminute, yminute);  
        g.drawLine(xcenter - 1, ycenter, xminute, yminute);  
        g.setColor(Color.green);  
        g.drawLine(xcenter, ycenter - 1, xhour, yhour);  
        g.drawLine(xcenter - 1, ycenter, xhour, yhour);  
        
        lastxs = xsecond;  
        lastys = ysecond;  
        lastxm = xminute;  
        lastym = yminute;  
        lastxh = xhour;  
        lastyh = yhour;  
    }  
    public void start() {  
        if (thread == null) {  
            thread = new Thread(this);  
            thread.start();  
        }  
    }  
    public void stop() {  
        thread = null;  
    }  
    public void run() {  
        while (thread != null) {  
            try   
            {  
                Thread.sleep(100);  
            }   
            catch (InterruptedException e) {}  
            repaint();  
        }  
        thread = null;  
    }  
    public void update(Graphics g) {  
        paint(g);  
    }  
    public static void main(String args[]) {  
        JFrame window = new JFrame();  
        Color c = new Color(118, 73, 190);  
        window.setBackground(c);  
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
        window.setBounds(0, 0, 400, 400);  
        Clock clock = new Clock();  
        window.getContentPane().add(clock);  
        window.setVisible(true);  
        clock.start();  
    }
}