JTree Display Update

Question

I use a JTree that requires periodic changes to its nodes. I cannot get the display of the JTree to update however. I have tried many different things such as JTree.updateUI(), DefaultTreeModel.reload(), DefaultTreeModel.nodesChanged().
Currently my code looks like this:
// initialization
createTreeNodes();
treeModel = new DefaultTreeModel(rootNode); treeModel.addTreeModelListener(this);
tree = new JTree(treeModel);
// code invoked whenever changes to JTree must be made
createTreeNodes();
treeModel.reload();
tree.repaint();
// this is the function "createTreeNodes"
private void createTreeNodes()
rootNode = new DefaultMutableTreeNode("File Name");
DefaultMutableTreeNode headerNode = new DefaultMutableTreeNode("Header 1");
for(int i=0; i<cardArray.size(); i++)
DefaultMutableTreeNode cardNode = new DefaultMutableTreeNode(cardArray.get(i).getFront() + " (" + (i+1) + ")");
// above line simply creates a node with a string
System.out.println(cardArray.get(i).getFront() + " (" + (i+1) + ")");
// the above line recreates the code 2 lines above for debugging purposes
headerNode.add(cardNode);
// above code adds child to parent
rootNode.add(headerNode);
// above code adds parent to root node
}The tree is updated in createTreeNodes().
If a file is opened by a user, cardArray changes and I reflect these changes by updating the JTree. The System.out.println() statement in the createTreeNodes() function prints the expected data to the console, which proves that the data is being updated. The display of the JTree does not update however.
And for further explanation about my code:
- the part that I commented "Initialization" is located in the program constructor. At this point cardArray is equal to 0, and the program simply displays one leaf node with a value of 'null'
- If the user opens a new file, cardArray (an ArrayList) is updated. I call the createTreeNodes() function which updates the JTree data. I also call treeModel.reload() to signal to the DefaultTreeModel that its data has been updated
- the function 'createTreeNodes()' simply adds DefaultMutableTreeNodes to the JTree hierarchy
My thanks in advance for any help you may be able to provide.

Answer 1

Hi,
I have taken a look at your code, and I can't see that you are updating the tree. Your createTreeNodes method does only create a new root node, and stores the reference in the attribute rootNode. That does neither affect the root or the model created in the initialization block.
/Kaj