import java.util.*;
import javax.swing.*;
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Container;
import java.awt.event.*;

public class Clock
    extends JFrame implements Runnable
{
    private Thread clockThread = null;
    private Time time;
    private long accumTime = 0L;
    private long startTime = -1L;
    
    public static void main( String[] args )
    {
        Clock clock = new Clock();
        clock.show();
    }
    
    public Clock()
    {
        super( "Clock" );
        setDefaultCloseOperation( EXIT_ON_CLOSE );
        JPanel buttons = new JPanel();
        JButton bStart = new JButton( "start" );
        bStart.addActionListener( new ActionListener() {
            public void actionPerformed(ActionEvent e) { start(); } } );
        JButton bStop = new JButton( "stop" );
        bStop.addActionListener( new ActionListener() {
            public void actionPerformed(ActionEvent e) { stop(); } } );
        JButton bReset = new JButton( "reset" );
        bReset.addActionListener( new ActionListener() {
            public void actionPerformed(ActionEvent e) { reset(); } } );
        buttons.add( bStart );
        buttons.add( bStop );
        buttons.add( bReset );
        Container content = getContentPane();
        content.add( buttons, BorderLayout.NORTH );
        time = new Time();
        content.add( time, BorderLayout.CENTER );
        setSize( 240, 120 );
        startTime = System.currentTimeMillis();
    }
    
    private void start() {
        if (clockThread == null) {
            clockThread = new Thread(this, "Clock");
            startTime = System.currentTimeMillis();
            clockThread.start();
        }
    }
    
    private void stop() {
        if ( clockThread != null )
        {
            clockThread = null;
            accumTime += System.currentTimeMillis() - startTime;
        }
        time.repaint();
    }
    
    private void reset() {
        accumTime = 0L;
        startTime = System.currentTimeMillis();
        time.repaint();
    }
    
    public void run() {
        Thread myThread = Thread.currentThread();
        while (clockThread == myThread) {
            time.repaint();
            try {
                Thread.sleep(100);
            } catch (InterruptedException e){}
        }
    }
    
    private class Time extends JPanel
    {
        Font timeFont = new Font( "SansSerif", Font.BOLD, 32 );
        private static final int timeX = 60;
        private static final int timeY = 40;
        
        public void paintComponent(Graphics g) {
            super.paintComponent( g );
            long ticks;
            if ( clockThread == null )
                ticks = accumTime;
            else
                ticks = System.currentTimeMillis() - startTime + accumTime;
            long tenths = ticks/100L;
            long seconds = tenths/10L; tenths %= 10;
            long minutes = seconds/60L; seconds %= 60;
            StringBuffer sb = new StringBuffer();
            if ( minutes < 10 )
                    sb.append( '0' );
            sb.append( minutes );
            sb.append( ':' );
            if ( seconds < 10 )
                    sb.append( '0' );
            sb.append( seconds );
            sb.append( '.' );
            sb.append( tenths );
            g.setFont( timeFont );
            g.drawString(sb.toString(), timeX, timeY);
        }
    }
}