Using SwingWorker and Timer to display time on a label?

Question

I want to have a clock showing current time and refreshes every second. The code I am using is:

int timeDelay = 1000;
ActionListener time;
time = new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent evt) {
            timeLabel.setText(DateTimeUtil.getTime()); 
            /*timeLabel is a JLabel to display time,
            getTime() is samll static methos to return formatted String of current time */
        }
    };
SwingWorker timeWorker = new SwingWorker() {

        @Override
        protected Object doInBackground() throws Exception {

            new Timer(timeDelay, time).start();
            return null;
        }
    };
timeWorker.execute();

What I want to refresh the timeLabel text in another thread other than EDT.
Am I doing it correct? Any other better way?
Also for information, i've added timeLabel to a extendedJPanel which contains few similar kinds of utilities, and is called in another MainJFrame.

In addition to the excellent advice from @Jonas (1+), one thing that you're doing wrong is making Swing calls from within a background thread. SwingWorker's `doInBackground()` method should contain no Swing calls that cannot be called on a background thread, meaning that you should most definitely not create a Swing Timer inside of this method, nor call `start()` on a Swing Timer object here. — Hovercraft Full Of Eels, Mar 24 '12 at 20:14
+1 for this advice. Thank You. One more thing is, `doInBackground()` cannot contain Swing calls - is that mean I should not initializes swing components inside frame like panels, buttons etc via `SwingWorker`? — Asif, Mar 24 '12 at 20:42
Absolutely correct. SwingWorker is for non-Swing initialization and for communication with Swing via publish, process, and done methods. — Hovercraft Full Of Eels, Mar 24 '12 at 20:52

score 14 · Accepted Answer · answered Mar 24 '12 at 20:10

14

You can do this without a SwingWorker, because this is what the Swing Timer is made for.

int timeDelay = 1000;
ActionListener time;
time = new ActionListener() {

    @Override
    public void actionPerformed(ActionEvent evt) {
        timeLabel.setText(DateTimeUtil.getTime()); 
        /* timeLabel is a JLabel to display time,
           getTime() is samll static methos to return 
           formatted String of current time */
    }
};

new Timer(timeDelay, time).start();

answered Mar 24 '12 at 20:10

Jonas

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Is the Actions in swing Timer is itself start in a different thread?? – Asif Mar 24 '12 at 20:39
1

@Asif: The action is executed on the EDT, because alla GUI modifications most be made from the EDT. – Jonas Mar 24 '12 at 20:47
@Asif: Conversely, the timer's `delay` happens on a different thread. – trashgod Mar 24 '12 at 21:54

Using SwingWorker and Timer to display time on a label?

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