急问JTree的问题。

对树进行删除操作。并且同时用向上向下建移动树结点。偶尔会报出这样的异常。程序中没有办法catch到，甚至我把整个程序快都try。我觉得是越界的问题。但是抛这个异常的时候，我算了下树的节点数目大于12。请大家给点意见。treeItemList.getPathForRow(iCount).getLastPathComponent()
treeItemList.setSelectionRow(nextCount);
treeItemList.scrollRowToVisible(nextCount);程序中主要用上面的语句来控制的。
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Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 12 >= 12
at java.util.Vector.elementAt(Vector.java:432)
at javax.swing.tree.DefaultMutableTreeNode.getChildAt(DefaultMutableTreeNode.java:230)
at javax.swing.tree.DefaultTreeModel.getChild(DefaultTreeModel.java:156)
at javax.swing.tree.FixedHeightLayoutCache$VisibleFHTreeStateNodeEnumeration.nextElement(FixedHeightLayoutCache.java:1506)
at javax.swing.tree.FixedHeightLayoutCache$VisibleFHTreeStateNodeEnumeration.nextElement(FixedHeightLayoutCache.java:1461)
at javax.swing.plaf.basic.BasicTreeUI.paint(BasicTreeUI.java:1153)
at javax.swing.plaf.ComponentUI.update(ComponentUI.java:142)
at javax.swing.JComponent.paintComponent(JComponent.java:743)
at javax.swing.JComponent.paint(JComponent.java:1006)
at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4972)
at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4925)
at javax.swing.JComponent._paintImmediately(JComponent.java:4868)
at javax.swing.JComponent.paintImmediately(JComponent.java:4675)
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)