4

I want to use the swing worker thread to update my GUI in swing. pls any help is appreciated.I need to update only the status of 1 field using the thread i.e setText().

Eng.Fouad
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SadanandM
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1 Answers1

8

I just answer similar question on another forum for a question about SwingWorker:

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.Timer;


public class Main extends JFrame 
{
    private JLabel label;
    private Executor executor = Executors.newCachedThreadPool();
    private Timer timer;
    private int delay = 1000; // every 1 second

    public Main()
    {
        super("Number Generator");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(300, 65);
        label = new JLabel("0");
        setLayout(new FlowLayout());
        getContentPane().add(label, "Center");
        prepareStartShedule();
        setVisible(true);
    }
    public static void main(String[] args)
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            @Override
            public void run()
            {
                new Main();
            }
        });
    }

    private void prepareStartShedule()
    {
        timer = new Timer(delay, startCycle());
        timer.start();
    }

    private Action startCycle()
    {
        return new AbstractAction()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                executor.execute(new MyTask());
            }
        };
    }

    private class MyTask extends SwingWorker<Void, Integer>
    {
        @Override
        protected Void doInBackground() throws Exception
        {
            doTasksInBackground();
            return null;
        }

        private void doTasksInBackground()
        {
            publish(generateRandomNumber());
        }

        private int generateRandomNumber()
        {
            return (int) (Math.random() * 101);
        }

        @Override
        protected void process(List<Integer> chunks)
        {
            for(Integer chunk : chunks) label.setText("" + chunk);
        }

    }
}

ps: @trashgod helps me a month ago to understand how to deal with SwingWorker (Can't get ArrayIndexOutOfBoundsException from Future<?> and SwingWorker if thread starts Executor), so thanks to him.


EDIT: The code is corrected. Thanks @Hovercraft Full Of Eels

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Eng.Fouad
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  • If do tasksInBackground takes any time (not in this example, but perhaps in the real program), it should be done inside of the SwingWorker, and s should be passed into a publish(...) method call, and then placed into the label via the process method. The SwingWorker would then change to generic type. Given the method's name, I'm 99% sure that this is the right thing to do. – Hovercraft Full Of Eels Sep 26 '11 at 11:09
  • +1 Good update, and thanks; credit to takteek, too. I was curious about using `Executor` in this context and found this helpful [article](http://java.sun.com/products/jfc/tsc/articles/threads/threads3.html). – trashgod Sep 26 '11 at 16:23