Can't collapse treepath after setmodel method

Question

Hi
I'm writing app client for my ejb modules. I have entity bean named Category, and I want navigate through them using JTree. Everything is ok, but when I add new category in my app, I'm refreshing JTree and I'm loosing my selection path - all nodes are collapsed. That's my code (only add method):
javax.swing.tree.TreePath treePath = categoryTree.getSelectionPath();
javax.swing.tree.DefaultMutableTreeNode treeNode = (javax.swing.tree.DefaultMutableTreeNode)categoryTree.getLastSelectedPathComponent();
CategoryTreeNode categoryTreeNode = (CategoryTreeNode)treeNode.getUserObject();
int categoryId = categoryTreeNode.categoryId;
if(categoryNameText.getText().length() == 0)
return;
new CategoryCreate(categoryId, categoryNameText.getText());
categoryTree.setModel(new CategoryTreeObject().jTree.getModel()); // here I acquire new jTree (with added node) and swap models in my jTree which is displayed
categoryTree.setSelectionPath(treePath);
categoryTree.expandPath(treePath); // should it work here?
Thanks,
Michael

Answer 1

Presumably when you create a new tree model it contains new DefaultMutableTreeNodes?
Since your selected path is defined by "old" tree nodes and your new model has "new" tree nodes the old path doesn't match a path in the new model.
I think DefaultMutableTreeNode doesn't use the user object to determine equality. If you're confident that your user object uniquely identifies the node then you could subclass DefaultMutableTreeNode to use that user object in its equals method.
Ideally you'd get your model to reload only the bit you're interested in (ie, mutate it - as the name suggests!).
Hope this helps.