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Re: (newbie) How to get t

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  Re: (newbie) How to get t "RedGrittyBrick" <redgrittybrick@THRWHITE.remove-dii-this> - 2011-04-27 15:46 +0000

#3732 — Re: (newbie) How to get t

  To: comp.lang.java.gui
Knute Johnson wrote:
> mrstephengross wrote:
>> So here's my next swing question: I've got a combo box with an action
>> listener. When you make a selection from the combo box, the action
>> listener fires off and does a bunch of stuff that takes a few seconds
>> to execute.
>>
>> However! While the action listener is executing, the combo box does
>> NOT collapse. That is, I would expect it to first collapse (with the
>> new selection highlighted) and THEN fully executed the action
>> listener's code.
>>
>> Is there a way to do this? I've been trying out various
>> implementations of the action listener to get it work, such as:
>>
>>   public void actionPerformed(ActionEvent e)
>> {   comboBox.setPopupVisible(false); /* do other stuff */; }
>>   public void actionPerformed(ActionEvent e) {   comboBox.validate(); /
>> * do other stuff */; }
>>   public void actionPerformed(ActionEvent e)
>> {   applicationFrame.validate(); /* do other stuff */; }
>>
>> But nothing seems to work. I've even tried the:
>>   SwingUtilities.invokeLater(new Runnable() { comboBox.validate(); /
>> *...*/ });
>>
>> trick, to no avail. Any ideas? Or am I just misunderstanding the UI's
>> built-in behavior?
>>
>> Thanks,
>> --Steve
> 
> You are blocking the Event Dispatch Thread.  ActionListener (and most 
> other listeners) perform their event handling on the EDT.  So while your 
> code is off for a few seconds it is preventing your GUI from updating. 
> Just wrap your time consuming code in a Runnable and start another thread.
> 
> public void actionPeformed(ActionEvent ae) {
>     Runnable r = new Runnable() {
>         public void run() {
>             // time consuming task
>         }
>     };
>     new Thread(r).start();
> }
> 
> If you have to update the GUI with the results of your time consuming 
> task you may or may not have to wrap that code in 
> EventQueue.invokeLater() to get it to execute on the EDT.  Most Swing 
> methods are not thread safe and need to be executed on the EDT.  Check 
> the docs for which are which.
> 

The SwingWorker class is well worth using IMO.


-- 
RGB

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