Updating swt ui from another thread every second

Question

I am working on a SWT java project for MAC OS, i need to add a label on SWT UI where i have to show the current time, updating on every second. I tried it i.e.

final Label lblNewLabel_1 = new Label(composite, SWT.CENTER);
FormData fd_lblNewLabel_1 = new FormData();
fd_lblNewLabel_1.left = new FormAttachment(btnNewButton_call, 10);
fd_lblNewLabel_1.bottom = new FormAttachment(100, -10);
fd_lblNewLabel_1.right = new FormAttachment(btnTransfer, -10);
fd_lblNewLabel_1.height = 20;
lblNewLabel_1.setLayoutData(fd_lblNewLabel_1);
    getDisplay().syncExec(new Runnable() {

            @Override
            public void run() {
                while(true){
                    lblNewLabel_1.setText(Calendar.getInstance().getTime().toString());

                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                }   
            }
        });

but its not working, please help me do that. thanks in advance.

score 6 · Answer 1 · answered Apr 16 '13 at 14:58

6

Better use org.eclipse.swt.widgets.Display.timerExec(int, Runnable) method to update UI on timely manner.

answered Apr 16 '13 at 14:58

sambi reddy

3,065
1
13
10

score 3 · Accepted Answer · answered Apr 16 '13 at 15:03

You're not updating the UI from another thread - you're updating the UI thread from itself.

sleeping on the UI thread will prevent the UI thread from doing things like painting, so it will appear that your program has hung.

Instead of schedule the UI thread to run a Runnable that updates a widget and sleeps for a second, you want a thread that sleeps every second and then schedules a Runnable that updates the widget and then exits quickly.

For example:

while(true)
{
    getDisplay().asyncExec(new Runnable() {
        lblNewLabel_1.setText(Calendar.getInstance().getTime().toString());
    });

    Thread.sleep(1000);
}

score 0 · Answer 3 · answered Apr 17 '13 at 08:00

0

I did it exactly..using following code

Thread timeThread = new Thread() {
            public void run() {
                while (true) {
                    display.syncExec(new Runnable() {

                        @Override
                        public void run() {
                            lblNewLabel_1.setText(Calendar.getInstance().getTime().toString());
                        }
                    });

                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        };

        timeThread.setDaemon(true);
        timeThread.start();

answered Apr 17 '13 at 08:00

Mukesh Kumar Singh

4,512
2
22
30

Looks like you used the approach from @EdwardThomson. You should upvote and accept his answer then... – Baz Apr 17 '13 at 10:54
I have accepted his answer but cant up-vote because for that minimum 15 reputation required. – Mukesh Kumar Singh Apr 17 '13 at 11:12
Now you have 15 reputation ;) – Baz Apr 17 '13 at 11:37
@Mukesh Kumar: Sambi reddys answer is more appropriate. – Favonius Apr 18 '13 at 09:43
1

I don't think so, because when i used that method that run only one time not periodical. i called that i.e.`display.timerExec(1000, new Runnable() { @Override public void run() { lblNewLabel_1.setText(Calendar.getInstance().getTime().toString()); } });` – Mukesh Kumar Singh Apr 18 '13 at 13:36

Updating swt ui from another thread every second

3 Answers3