Why do we have to use SwingUtilities.invokeLater() to update UI status?

I just don't understand very well why we have to use SwingUtilities.invokeLater() to update UI status. Why not just new a thread in actionPerformed() method and do time consuming tasks in this thread and update UI status in it? Some tutorials say it is not safe to update UI status not in Event Dispatch Thread, I don't understand, why is it not safe? Can anyone provide a scenario for this? I just write an example, a button and a progressbar, click button, progressbar keeps updating value. I just create a new thread to do this, don't find any issue. Thanks.

[Swing single threaded rule|http://www.lmgtfy.com/?q=swing+single+threaded+rule]
db

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Why do we have to call SwingUtilities.invokeLater()??

Hello,
i am not understanding the concept of SwingUtilities.invokeLater() i read the documentation but still couln't get why it is needed and when it is needed?do we have to call this function everytime some event is generated and some action is performed on component Ex.mouse click on button etc?? Please give me little details regarding it's concept!
Thanks in advance :)

(guys correct me if i'm wrong here)Most of the time that's correct, but for some customizations it is necessary to run custom code after all default code contained in the Swing classes has been executed. For example, to request focus be given to a component that would otherwise not be immediately focused, if you omit to enclose that in a invokeLater, it will get the focus but immediately lose it as still-queued events mandate the transfer of focus elsewhere. Moreover, as the event delivery mechanism is asynchronous, the behavior may be inconsistent.
In general, any customization that may conflict with the normal flow should be wrapped in invokeLater, whether run from the EDT or another thread. The exceptions here are methods which the API declares to be thread safe.
what you want to do is run that time consuming process in a thread, and when you need to call back to update the GUI, then use SwingUtilities.invokeLater.Or use SwingWorker, that's what it's for.
cheers, db

Is it safe to use SwingUtilities.invokeLater(), while updating GUI?

Hi,
I am updating GUI components in synchronized block which is runinng on main() thread my application hangs, but if I use SwingUtilities.invokeLater(...) then it runs fine.
My question is:
Is it safe to use SwingUtilities.invokeLater(...) in synchronized block.
Edited by: Amol_Parekh on Nov 1, 2007 1:28 AM

Paul Hyde in his "Java Thread Programming" (great book!!!) says it is.
With invokeLater() you say to the Thread Scheduler you want that code to run on the Swing thread. In fact, if that is the only thing you do in the synchronized block I think it is unnecessary.
Greetings,
astrognom

Should I use a SwingWorker or SwingUtilities.invokeLater() to update my UI?

Are there specific situations where you want to use method above the other? This whole swing concurrency is very new to me, and I don't really know where to begin.

When executing long running code you don't want the GUI to freeze. Therefore you have two things to be concerned about. First, you want the long running task to execute in a separate Thread. Secondly, when you need to update the GUI from this code you need to make sure the code executes on the Event Dispatch Thread (EDT).
You can code this manually by creating a separate Thread and then use SwingUtilities.invokeLater() when necessary.
A SwingWorker tries to simplify this process by having a simple API where you can add code that executes on a separate Thread or where you can add code that executes on the EDT.
So in the case of managing long running tasks, the end result should be the same.
Hwever, there are times when I know code is already executing on the EDT, but I sometimes use invokeLater(..) to force my code to the end of the EDT. This is used in special situations when code doesn't execute in the order you want.
For example, I've tried to add a FocusListener to a JFormattedTextField to "select the text" when it gains focus. The problem is the the UI also adds a FocusListener. Because of the way listeners are handled the last listener added to the component executes first. Therefore, using the invokeLater() forces my listener code to execute last.
You can try this code to see what I mean:
KeyboardFocusManager.getCurrentKeyboardFocusManager()
     .addPropertyChangeListener("permanentFocusOwner", new PropertyChangeListener()
     public void propertyChange(final PropertyChangeEvent e)
          if (e.getNewValue() instanceof JTextField)
               // invokeLater needed for JFormattedTextField
               SwingUtilities.invokeLater(new Runnable()
                    public void run()
                         JTextField textField = (JTextField)e.getNewValue();
                         textField.selectAll();
});Edited by: camickr on Mar 5, 2011 2:36 PM

Why do i have to use nextLine() when there is an InputMismatchException

I dont understand why do i have to use this line of code to avoid an infinite loop here...help appreciated.
import java.util.Scanner;
import java.util.InputMismatchException;
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Rix87 wrote:
When i run the program if i input something that triggers the exception, it infinitely loops through the question and the catch method block outputs, weirdest thing of all is that i can't even input again after the exception is thrown, but with nextLine() it avoids that, but i still dont understand why do i have to use nextLine().Exactly what I said.
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Your question does not make sense. Please clarify.
GamingChamp wrote:
WHy should we have to use to update ipod touch

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Why do I have to use SELECT INTO clause in a Stored Proc ?

Hi,
I'm new to oracle. I've bought Oracle Database 10g SQL and Oracle Database 10 A beginner's Guide, two books from Oracle press but I can't find any answer for that.
Why when I'm writing a Stored Procedure with a SELECT statement do I have to use an INTO clause ?? And why when the select returns more than one row do I have to use a cursor ? By the way is this the only way to return more than one row from a stored procedure ?
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EJB function using SwingUtilities.invokeLater() is problm msg publishing

My problem for JMS using Message publish to group of people , What I did, Server side I am pushing message for each topic , (it could be n number of topic ) I created for Every five topic to as single thread. (Topic will be [ 200 ~2000] ) ,
Some time this SwingUtilities.invokeLater() function will shown error Message AWT event
I am using EJB Method for like this.
new Thread()
public void run()
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public void run() {
     HashMap map=null;
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          InitialContext iniCtx=(InitialContext)map.get("InitialContext");
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          for(int i=0;i<userlist.length;i++)
               try
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               catch(Exception gexp)
          close(map); // // to closing connection function .
     catch(Exception exp)
          close(map); // to closing connection function .
exp.printStackTrace();
}.start();
Thanks in advance
Sasikumar (Sasimsit)

{color:red}{size:20px}TRIPLE POSTED{size}{color}
[http://forums.sun.com/thread.jspa?threadID=5333442]
[http://forums.sun.com/thread.jspa?threadID=5333443]
[http://forums.sun.com/thread.jspa?threadID=5333445]
Cross posting is rude.
db

Why do we have to use SwingUtilities.invokeLater() to update UI status?

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