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Refreshing JTree without using DefaultTreeModel

Posted on 2004-03-21
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Last Modified: 2007-12-19
I need to dynamically change the display information of tree nodes (e.g. node text), and then refresh the entire JTree so that my changes are displayed.

DefaultTreeModel has lots of useful methods that I could use to refresh the tree (e.g. reload()), however, there is no guarantee that the JTree will be using DefaultTreeModel.

Is there a way to refresh the tree without using DefaultTreeModel?

I am temporarily using the following code for the refresh:
    if(tree.isExpanded(rootPath)) {
      // Note the currently selected path so that it can be
      // restored after the tree is refreshed.
      TreePath selectedPath = tree.getSelectionPath();

      // Do the "refresh".
      tree.collapsePath(rootPath);
      tree.expandPath(rootPath);
      // The selection path will now be set to rootPath.

      // Restore the old selection path.
      tree.setSelectionPath(selectedPath);
    }

But this will fire unwanted TreeSelectionEvents, so I would prefer another solution.
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Question by:xelia
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Expert Comment

by:objects
ID: 10647090
You have to fire the relevant events from the TreeModel, this does not have to be a DefaultTreeModel, but it needs to come from the model.
Any other solution, such as refreshing the model, would cause you to lose your selection as you have already experienced.
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Author Comment

by:xelia
ID: 10655309
Thanks objects,

I'll ask the people who created the tree model if they are firing the event when the node's data changes.
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Author Comment

by:xelia
ID: 10673233
Unfortunately their TreeModel is not firing events when the nodes' contents changes, and I don't have access to the source code.
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Author Comment

by:xelia
ID: 10673375
It would be nice to have a utility method to refresh any JTree, no matter what its model is doing:

public static void refreshAll(JTree tree) {
  // Do refresh here.
}
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Accepted Solution

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objects earned 300 total points
ID: 10674047
> It would be nice to have a utility method to refresh any JTree

There is: setModel().
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Author Comment

by:xelia
ID: 10674349
This works, but like you were saying before, the selected path gets lost.  :(
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LVL 92

Expert Comment

by:objects
ID: 10674364
yes, as the tree has no way of knowing whether the underlying model data has changed or not so it has to clear any state such as selection.
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Author Comment

by:xelia
ID: 10674437
Thanks objects - that answered my next question (why changing the model was firing TreeSelectionEvents).
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LVL 92

Expert Comment

by:objects
ID: 10700752
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