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Threding issue when populating a table

Posted on 2006-11-08
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Last Modified: 2008-02-01
Hi,

I have been testing SwingWorker to gain more performance to our app. I use SwingWorker when I
need to update a table from database. In some cases it is working perfectly, but in some it is giving
me an exception.

Here is what I do:

When a window is opened or a value in combo is changed, etc. I need to update table from database.
With SwingWorker I can do this in another thread (than EDT), so GUI remains usable. I'll start the
update like following:

        SwingWorker sw = new SwingWorker() {
            protected Object doInBackground() throws Exception {
                updateTable();
                return null;
            }
        };
        sw.execute();

I have tried to add fireTableDataChanged(); to my table model and to ignore repaint for the table while updateing.

/ mika
0
Comment
Question by:JamixOy
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8 Comments
 

Author Comment

by:JamixOy
ID: 17904596
Forgot to include the Exception..

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 2 >= 0
      at java.util.Vector.elementAt(Vector.java:432)
      at javax.swing.table.DefaultTableColumnModel.getColumn(DefaultTableColumnModel.java:280)
      at javax.swing.plaf.basic.BasicTableHeaderUI.paint(BasicTableHeaderUI.java:337)
      at javax.swing.plaf.ComponentUI.update(ComponentUI.java:142)
      at javax.swing.JComponent.paintComponent(JComponent.java:740)
      at javax.swing.JComponent.paint(JComponent.java:1003)
      at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4930)
      at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4883)
      at javax.swing.JComponent._paintImmediately(JComponent.java:4826)
      at javax.swing.JComponent.paintImmediately(JComponent.java:4633)
      at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:451)
      at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:114)
      at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
      at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

/ mika
0
 
LVL 92

Expert Comment

by:objects
ID: 17904603
you can't update your table from a different thread. table updates need to be done from the EDT
0
 
LVL 92

Accepted Solution

by:
objects earned 1200 total points
ID: 17904605
use EventQueue.invokeLater() & invokeAndWait() to do the updates from the EDT
0
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Author Comment

by:JamixOy
ID: 17904642
Hi Objects,

invokeLater() is working ok, but I guess the GUI locks if a long query is issued from the database?

I have created a component that looks something like a table, but it uses javax.swing.JLists and it is updateing ok in a another thread. Is there some danger using SwingWorker like this?

/ mika
0
 
LVL 92

Expert Comment

by:objects
ID: 17904674
> but I guess the GUI locks if a long query is issued from the database?

it will, the long query should be done in seperate thread.
0
 

Author Comment

by:JamixOy
ID: 17904702
Ok, so there is a little designing issue here.. :)

Thanks, Objects.
0
 

Author Comment

by:JamixOy
ID: 17904799
Hi Objects,

Changed my code like this:

        SwingWorker sw = new SwingWorker() {
            protected Object doInBackground() throws Exception {
                fetchDataFromDatabase();
                return null;
            }
            public void done() {
                updateTableWithNewData();
            }
        };
        sw.execute();

This looks like working ok.

/mika
0
 
LVL 92

Expert Comment

by:objects
ID: 17904914
that looks better :)
0

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