JTree update nodes without collapsing

Question

I have a Java SE 7 application that needs to have the JTree nodes updated. From the tutorial given by Oracle using this thread, there's no given hint on how I could update the label (displayed text of the node on the Tree) on code. Currently I am using DefaultTreeModel as the model of my JTree and DefaultMutableTreeNode as the nodes of the said Tree.

To further detail about the application I am working on, I am developing a chat facility having the contact(s) displayed with their availability status (whether Online, Offline, etc.) per account.

The question is, how can I update the displayed text of a particular node without (at most) removing it from it's parent and adding it on it's designated index. Like a DefaultMutableTreeNode.setText("<new label>")?

---

UPDATE : January 20, 2013

Redefined the question for clarifications.

Answer 1

Perhaps if you use 'nodeChanged()' instead of 'reload()' you will get the effect you desire.

There are a bunch of methods on the DefaultTreeModel class that cause various parts of the tree to be changed and redrawn. There are also other methods on DefaultTreeModel that only cause redrawing to take place.

You mentioned 'reload(node)' and commented that it causes the tree to collapse when you call it. 'reload' causes the entire sub-tree to be completely redrawn starting at that node. (But if that node isn't visible, it changes nothing.) That is called a 'structure change'.

'insertNodeInto()' and 'removeNodeFromParent()' modify the tree structure by adding or removing the node and then redrawing.

I think 'nodeChanged()' is the one you need since it just notifies the model that something changed in the node that will cause it to display differently. Perhaps the displayable text is now different than it was. Perhaps you changed the user object in the node. That's when you call 'nodeChanged()' on a node.

You should try 'nodeChanged()' in place of the 'reload()' call in your own code that was collapsing and in the example program vels4j provided. This might take care of the problem.

Note that there are also two other families of methods on the DefaultTreeModel that are used in other cases:

These methods work with the tree nodes and use the tree path to define where the change took place. They do not change the data structures underlying the tree but notify the model that something changed so it can notify the listeners that actually redraw things or otherwise respond to changes.

nodesWereInserted() nodesWereRemovde() nodesChanged() nodeStructureChanged()

There are also a set of fire...() methods that are used internally to the DefaultTreeModel and any sub-classes you may create. They merely notify any listeners that something changed. Notice that they are protected.