我在Java Swing中遇到异常，但是程序继续正常运行。 我应该担心吗？

Question

I'm using a SwingWorker to update parts of the GUI, and I'm relatively new to using them so I'm not sure what's causing this or if it's important. Basically, when this one big process finishes collecting data from online, the SwingWorker tells a JTable to update with the new information. And it does, and the GUI works exactly as it should. However, the console prints this Exception:

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 19 >= 18
at java.util.Vector.elementAt(Vector.java:470)
at javax.swing.table.DefaultTableModel.getValueAt(DefaultTableModel.java:649)
at javax.swing.JTable.getValueAt(JTable.java:2720)
at javax.swing.JTable.prepareRenderer(JTable.java:5718)
at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2114)
at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:2016)
at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1812)
at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
at javax.swing.JComponent.paintComponent(JComponent.java:778)
at javax.swing.JComponent.paint(JComponent.java:1054)
at javax.swing.JComponent.paintChildren(JComponent.java:887)
at javax.swing.JComponent.paint(JComponent.java:1063)
at javax.swing.JViewport.paint(JViewport.java:725)
at javax.swing.JComponent.paintChildren(JComponent.java:887)
at javax.swing.JComponent.paint(JComponent.java:1063)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5221)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1482)
at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1413)
at javax.swing.RepaintManager.paint(RepaintManager.java:1206)
at javax.swing.JComponent._paintImmediately(JComponent.java:5169)
at javax.swing.JComponent.paintImmediately(JComponent.java:4980)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:770)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:728)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677)
at javax.swing.RepaintManager.access$700(RepaintManager.java:59)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1621)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:705)
at java.awt.EventQueue.access$000(EventQueue.java:101)
at java.awt.EventQueue$3.run(EventQueue.java:666)
at java.awt.EventQueue$3.run(EventQueue.java:664)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:675)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

And I hate this Exception, because it doesn't point to anywhere in my code. I know what happens right before this Exception, as I'd been trying to figure this out on my own for a while, but there's no point I can find where an ArrayOutOfBoundsError should be possible. I'm fairly certain it has something to do with updating the JTable, but the table works fine.

So, what I'm asking is, can anyone give me an idea as to why this is happening, and, should I even be concerned, since the program still works fine?

Edit: After extensive testing, I've determined I'm incapable of reproducing this Exception in another program. I've also found that it happens at a random time, but always after a call to a certain method in another class. This call is made from the process() method of the SwingWorker, and all it does is remove all rows from the DefaultTableModel, then add rows containing the new information, one at a time in a for loop. By printing to console, I've found that the Exception will be thrown before the for loops starts, after it ends, or at some random time during the for loop. I've had the entire thing run without the Exception occurring. This a general version of the method in question:

    for(int i = table.getRowCount() - 1; i >= 0; i--)
        model.removeRow(i);

    for(InfoObject o : listOfInfoObjects) {
        int[] stats = o.getStats();
        model.addRow(new Object[] {o.getName(),
        stats[0], stats[1], stats[2], stats[3], stats[4], stats[5]});
    }

I don't know if that's any help but it's all I've got to add, sorry.

Answer 1

The most likely cause of this is bad use of threading within your program. Swing runs a single thread called the Event Dispatch Thread and all changes to the controls, layouts, etc must be done from on that thread.

You can use SwingUtilties.invokeLater to execute code on the EDT.

http://docs.oracle.com/javase/tutorial/uiswing/concurrency/dispatch.html