Java clock isn't counting in Swing

Question

I am trying to make a stopwatch using swing, but it is not working. Here is my code. The Jlabel clock is always displaying -1, which should only happen if it is stopped. Am

Answer 1

Your StopWatch class run once and then terminates...

public void run() {
    // Start here
    SwingUtilities.invokeLater(new Runnable()
    {
        @Override
        public void run() {
            long time = getElapsedTime();
            sidePanel.this.clock.setText(String.valueOf(time));
        }
    });
    // End here...
}

A thread will terminate when it exists it's run method, in this case, your StopWatch's run method.

What you need to do to is maintain a loop until the isRunning becomes false

public void run() {
    while (isRunning) {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run() {
                long time = getElapsedTime();
                sidePanel.this.clock.setText(String.valueOf(time));
            }
        });
        // Because we really don't want to bombboard the Event dispatching thread
        // With lots of updates, which probably won't get rendered any way,
        // We put in a small delay...

        // This day represents "about" a second accuracy...
        try {
            Thread.sleep(500);
        } catch (Exception exp) {
        }
    }
}

It would much simpler to use a javax.swing.Timer though...

private Timer timer;
public void init()
{
    pane = new JPanel();
    pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));

    clock = new JLabel("00:00");

    toggle = new JButton("Start/Stop");
    toggle.addActionListener(this);

    pane.add(clock);
    pane.add(toggle);

    timer = new Timer(500, new ActionListener() { 
        public void actionPerformed(ActionEvent evt) {
            long time = getElapsedTime();
            sidePanel.this.clock.setText(String.valueOf(time));        
        }
    });
    timer.setRepeats(true);
    add(pane);

}

@Override
public void actionPerformed(ActionEvent e) {
    if(e.getSource() == toggle)
    {
        if(timer.isRunning())
        {
            endTime = System.currentTimeMillis();
            timer.stop();
        }
        else
        {
            startTime = System.currentTimeMillis();
            timer.start();
        }
    }
}

You can then strip out the functionality from you StopWatch (ie the getElapsedTime())