Rich client and scheduling

[Patrick Vanhuyse]

I would have code like :

interface JobListener {
  void begin();
  void end();
  void completed(int percent);
}

class Job extends TimerTask {
  JobListener listener;

  void run() {
     listener.begin();
     for (...) {
       listener.completed(i);
     }
     listener.end();
  }
}

class View extends AbstractView implements JobListener {
  void begin() {
     getStatusBar().setMessage("Begin"); // And/or other Swing stuff
  }
  void end() {
     getStatusBar().setMessage("End"); // And/or other Swing stuff
  }
  void completed(int percent) {
     getStatusBar().setMessage("Completed " + percent); // And/or other Swing stuff
  }
}

The job is scheduled using Spring Framework (org.springframework.scheduling.timer).

Since the job doesn't run in the Swing's thread, shouldn't this cause problem with Swing ?

I think it would.
How can I do that ?

[Keith Donald]

Yes, updating a swing widget in any thread but the event dispatching thread will cause a problem (flickering and the like.) The simplest solution is to use SwingUtilities.invokeLater(Runnable), to force execution in the event dispatching thread.

I wonder if Foxtrot would help out here.

[Patrick Vanhuyse]

There is also http://spin.sourceforge.net

I think these API can help to run long task from Swing.
Here I want to run a short task in the Swing thread from another thread.

Here is my code :

interface JobListener { 
  void begin(); 
  void end(); 
  void completed(int percent); 
} 

class Job extends TimerTask { 
  JobListener listener; 

  void run() { 
     doInSwing(new Runnable() { listener.begin(); });
     for (...) { 
     doInSwing(new Runnable() { listener.completed(); });
     } 
     doInSwing(new Runnable() { listener.end(); });
  } 

  private void doInSwing(Runnable runnable) {
    try {
      SwingUtilities.invokeAndWait(runnable);
    } catch (InterruptedException e) {
      // Logging
    } catch (InvocationTargetException e) {
      // Logging
    }
  }
} 

class View extends AbstractView implements JobListener { 
  void begin() { 
     getStatusBar().setMessage("Begin"); // And/or other Swing stuff 
  } 
  void end() { 
     getStatusBar().setMessage("End"); // And/or other Swing stuff 
  } 
  void completed(int percent) { 
     getStatusBar().setMessage("Completed " + percent); // And/or other Swing stuff 
  } 
}

Could be better if Swing handled multi-threading ! :wink:

[Patrick Vanhuyse]

Easier solution using Spin.

The code from first post unchanged.

Call to setJobListener :

job.setJobListener((JobListener) Spin.over(view));

[oliverhutchison]

Cool!

I've been meaning to look at Spin for some time. I had no idea it had this Spin.over funtionality IMO even more usfull than Spin.off. It's also a great little example of where AOP realy shines.

Thanks for pointing that out

Ollie