在重定位JTree中的节点时，Swing会抛出ArrayIndexOutOfBoundsException

Question

我想改变我的JTree中某些节点的位置。这是代码：

public void changeNodePositionInTree() {
   DefaultTreeModel model = (DefaultTreeModel)tree.getModel();

   for(int i = 0; i < someList.size(); i++) {
      DefaultMutableTreeNode node = findNodeInTreeByName(someList.get(i));

      //if node is in a tree, then change its location and insert it in position i
      if(node != null) {
         model.removeNodeFromParent(node);
         model.insertNodeInto(node, tree.getRoot(), i);
      }
   }
}

SwingUtilities.invokeLater(new Runnable() {
   public void run() {
      changeNodePositionInTree();
   }
});

我遇到这个代码的两个问题：

1. 有时很少有节点没有显示其文本，并且在末尾用一些截断和点（...）表示。
2. 有时我得到这个JRE异常，我不明白为什么。我认为它被抛出，因为我删除了一个节点，然后再次插入它，JRE尝试在这两个操作之前或之间重新绘制这个树。我怎么能避免这种情况？

     Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 22 >= 22
       at java.util.Vector.elementAt(Vector.java:474)
       at javax.swing.tree.DefaultMutableTreeNode.getChildAt(DefaultMutableTreeNode.java:245)
       at javax.swing.tree.VariableHeightLayoutCache$VisibleTreeStateNodeEnumeration.nextElement(VariableHeightLayoutCache.java:1695)
       at javax.swing.tree.VariableHeightLayoutCache$VisibleTreeStateNodeEnumeration.nextElement(VariableHeightLayoutCache.java:1653)
       at javax.swing.plaf.basic.BasicTreeUI.paint(BasicTreeUI.java:1183)
       at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
       at javax.swing.JComponent.paintComponent(JComponent.java:780)
       at javax.swing.JComponent.paint(JComponent.java:1056)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JViewport.paint(JViewport.java:728)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JSplitPane.paintChildren(JSplitPane.java:1047)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paint(JComponent.java:1065)
       at javax.swing.JLayeredPane.paint(JLayeredPane.java:586)
       at javax.swing.JComponent.paintChildren(JComponent.java:889)
       at javax.swing.JComponent.paintToOffscreen(JComponent.java:5217)
       at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1579)
       at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1502)
       at javax.swing.RepaintManager.paint(RepaintManager.java:1272)
       at javax.swing.JComponent.paint(JComponent.java:1042)
       at java.awt.GraphicsCallback$PaintCallback.run(GraphicsCallback.java:39)
       at sun.awt.SunGraphicsCallback.runOneComponent(SunGraphicsCallback.java:79)
       at sun.awt.SunGraphicsCallback.runComponents(SunGraphicsCallback.java:116)
       at java.awt.Container.paint(Container.java:1975)
       at java.awt.Window.paint(Window.java:3912)
       at javax.swing.RepaintManager$4.run(RepaintManager.java:842)
       at javax.swing.RepaintManager$4.run(RepaintManager.java:814)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
       at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:814)
       at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:789)
       at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:738)
       at javax.swing.RepaintManager.access$1200(RepaintManager.java:64)
       at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1732)
       at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
       at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
       at java.awt.EventQueue.access$500(EventQueue.java:97)
       at java.awt.EventQueue$3.run(EventQueue.java:709)
       at java.awt.EventQueue$3.run(EventQueue.java:703)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
       at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
       at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
       at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
       at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
       at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
       at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)

Answer 1

不要在模型上使用insertNodeInto方法而是在根节点上调用add，最后在传递根节点的模型上调用nodesChanged方法。代码如下，供您参考。

public void changeNodePositionInTree() {
   DefaultTreeModel model = (DefaultTreeModel)tree.getModel();
   DefaultMutableTreeNode root = ( DefaultMutableTreeNode ) tree.getRoot();
   for(int i = 0; i < someList.size(); i++) {
      DefaultMutableTreeNode node = findNodeInTreeByName(someList.get(i));

      //if node is in a tree, then change its location and insert it in position i
      if(node != null) {
         model.removeNodeFromParent(node);
         root.add( node );
      }
   }

   // inform node that the root node got changed
   model.nodeChanged(root);

}

SwingUtilities.invokeLater(new Runnable() {
   public void run() {
      changeNodePositionInTree();
   }
});