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Groups > comp.lang.java.gui > #4583

Re: Synchronization when collecting data from the EDT?

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On 07/06/2011 05:03, John B. Matthews allegedly wrote:
> Here's my (contrived) sscce. A javax.swing.Timer increments  an int at 
> 100 Hz, while a java.util.TimerTask samples the value at 1 Hz. I'd like 
> the API to be a little more explicit, but it does say that the calling 
> thread blocks and the Runnable's dispatch "will happen after all pending 
> events are processed."
> 
> import java.awt.EventQueue;
> import java.awt.event.ActionEvent;
> import java.awt.event.ActionListener;
> import java.lang.reflect.InvocationTargetException;
> import java.util.LinkedList;
> import java.util.TimerTask;
> import javax.swing.JFrame;
> import javax.swing.JLabel;
> import javax.swing.JPanel;
> import javax.swing.Timer;
> 
> /** @author John B. Matthews */
> public class TwoTimer extends JPanel {
> 
>     private Timer timer = new Timer(10, null);
>     private int value;
> 
>     public TwoTimer() {
>         final JLabel label = new JLabel("0");
>         timer.addActionListener(new ActionListener() {
> 
>             @Override
>             public void actionPerformed(ActionEvent e) {
>                 label.setText(String.valueOf(value++));
>             }
>         });
>         this.add(label);
>     }
> 
>     public int getValue() {
>         return value;
>     }
> 
>     public void startSwingTimer() {
>         timer.start();
>     }
> 
>     public void startUtilTimer() {
>         final LinkedList<Integer> samples = new LinkedList<Integer>();
>         java.util.Timer sampler = new java.util.Timer();
>         sampler.scheduleAtFixedRate(new TimerTask() {
> 
>             @Override
>             public void run() {
>                 try {
>                     EventQueue.invokeAndWait(new Runnable() {
> 
>                         @Override
>                         public void run() {
>                             samples.add(getValue());
>                         }
>                     });
>                 } catch (InterruptedException ex) {
>                     ex.printStackTrace(System.err);
>                 } catch (InvocationTargetException ex) {
>                     ex.printStackTrace(System.err);
>                 }
>                 System.out.println(samples.getLast());
>             }
>         }, 1000, 1000);
> 
>     }
> 
>     private void display() {
>         JFrame f = new JFrame("TwoTimer");
>         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
>         f.add(this);
>         f.pack();
>         f.setLocationRelativeTo(null);
>         f.setVisible(true);
>     }
> 
>     public static void main(String[] args) {
>         EventQueue.invokeLater(new Runnable() {
> 
>             @Override
>             public void run() {
>                 TwoTimer tt = new TwoTimer();
>                 tt.display();
>                 tt.startSwingTimer();
>                 tt.startUtilTimer();
>             }
>         });
>     }
> }
> 

John, is it intended that you didn't use a thread-safe producer/consumer
queue (a mere LinkedList)? I would have thought one would be necessary,
but since it touches upon the subject Knute brought to our attention,
I'm wondering whether there's some kind of point involved.

Also, the println(queue.getLast()) statement probably ought to go into
the try/catch block, lest you want to risk a NoSuchElementException.

-- 
DF.
Determinism trumps correctness.

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Thread

Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-04 17:38 -0700
  Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-04 17:50 -0700
  Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-05 17:52 +0200
    Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-05 10:47 -0700
      Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-05 23:47 -0400
        Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-05 22:11 -0700
          Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-06 14:31 +0200
          Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-06 23:03 -0400
            Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-07 18:51 +0200
              Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-07 13:38 -0400
                Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-08 00:10 +0200
                Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-07 23:51 -0400
                Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-10 01:17 +0200
                Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-10 01:25 +0200
                Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-09 22:34 -0400
                Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-10 05:22 +0200
                Re: Synchronization when collecting data from the EDT? markspace <-@.> - 2011-06-10 08:04 -0700
                Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-10 21:13 -0400
                Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-12 12:51 -0700
                Re: Synchronization when collecting data from the EDT? markspace <-@.> - 2011-06-07 23:31 -0700
                Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-08 23:07 -0700
                Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-09 18:35 -0400
                Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-12 12:45 -0700
            Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-08 23:05 -0700
              Re: Synchronization when collecting data from the EDT? "John B. Matthews" <nospam@nospam.invalid> - 2011-06-09 14:35 -0400
  Re: Synchronization when collecting data from the EDT? Roedy Green <see_website@mindprod.com.invalid> - 2011-06-05 13:39 -0700
    Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-05 22:17 -0700
      Re: Synchronization when collecting data from the EDT? markspace <-@.> - 2011-06-07 14:51 -0700
  Re: Synchronization when collecting data from the EDT? markspace <-@.> - 2011-06-05 17:46 -0700
    Re: Synchronization when collecting data from the EDT? Knute Johnson <nospam@knutejohnson.com> - 2011-06-05 22:41 -0700
      Re: Synchronization when collecting data from the EDT? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-06-06 14:35 +0200

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