Cronometro con pausa /riprendi

[misterlol]

Buonasera, dovrei sviluppare un cronometro che preveda la funzione di pause/resume. Sto utilizzando un codice trovato in internet per il cronometro ( che parte premendo start e si ferma premendo stop) ma non riesco ad implementare la pausa/riprendi, qualcuno può darmi una mano?

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

public class Cronometro {  
    private JFrame frame;  
    private JLabel labelTime;  
    private JPanel panelButtons;  
    private JButton buttonStart;  
    private JButton buttonStop;  
    private Timer timer;  
    private long startTime; 

public Cronometro() {  
    frame = new JFrame("Cronometro");  
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
    frame.setSize(220, 140);  
    labelTime = new JLabel("0:00:00.0");  
    labelTime.setFont (new Font("SansSerif", Font.BOLD, 30));  
    labelTime.setHorizontalAlignment(JLabel.CENTER);  
    buttonStart = new JButton("START");  
    buttonStop = new JButton("STOP");  
    buttonStop.setEnabled(false);  
    panelButtons = new JPanel(new GridLayout(1, 2));  
    panelButtons.add(buttonStart);  
    panelButtons.add(buttonStop);  
    frame.add(labelTime, BorderLayout.CENTER);  
    frame.add(panelButtons, BorderLayout.SOUTH);  
    timer = new Timer(100, new ActionListener() {  
        public void actionPerformed(ActionEvent e) {  
            long diffTime = System.currentTimeMillis() - startTime;  
            int decSeconds = (int)(diffTime % 1000 / 100);  
            int seconds = (int)(diffTime / 1000 % 60);  
            int minutes = (int)(diffTime / 60000 % 60);  
            int hours = (int)(diffTime / 3600000);  
            String s = String.format("%d:%02d:%02d.%d", hours, minutes, seconds, decSeconds);  
            labelTime.setText(s);  
        }  
    });  
    buttonStart.addActionListener(new ActionListener () {  
        public void actionPerformed(ActionEvent e) {  
            startTime = System.currentTimeMillis();  
            timer.start();  
            buttonStart.setEnabled(false);  
            buttonStop.setEnabled(true);  
        }  
    });  
    buttonStop.addActionListener(new ActionListener() {  
        public void actionPerformed(ActionEvent e) {  
            timer.stop();  
            buttonStart.setEnabled(true);  
            buttonStop.setEnabled(false);  
        }  
    });  
    frame.setVisible (true);  
}