JTree calling setSelectionPath() does not highlight new selection

Question

I have looked throughout many forum entries and this question has been asked a few times but I have not seen a solution that works at least for me.
When I do the following:
          TreePath path = new TreePath(...)
this.tree.setExpandsSelectedPaths(true);          // not sure if I need this
          this.tree.getSelectionModel().setSelectionPath( path ); // this alone should work correct?
          this.tree.scrollPathToVisible(path);
The original selection disappears (no highlighting) but the new one selected does not
I have also tried calling just for fun ...
     this.tree.getSelectionModel().resetRowSelection();
and this.tree.getSelectionModel().reload( path.getLastComponent() );
Does anybody have an idea of what may be going wrong ? The selection path is valid as I have verified it with the debugger.
Any ideas or suggestions are much appreciated
thanks
Doug

Answer 1

          TreePath path = new TreePath(...)
The devil is in the details... Unfortunately your case's details are in the ellipsis! :o)
Try to provide an SSCCE to get informed help, otherwise you can only hope that we guess well. That being said, here is my "guess":
A preliminary: JTree renders selection by comparing nodes pathes with the selection path(es).
As is common in the Java world, these comparisons rely on the equals() methods of the objets that make up the TreePath's components.
If any of the classes involved does not override equals, the corresponding components objects will be considered equals only if they are identical. In other words, a TreePath which contain a "new" instance of whatever class that does not override equals() will never be considered equal to any TreePath created formerly.
Now comes the gory part: DefaultMutableTreeNode (which is the most often common build block of TreeModels and TreePathes) does not override equals().
So if your TreePath are made of DefaultMutableTreeNode components, they will never be considered equal unless they use the same DefaultMutableTreeNode instances, which would somewhat not be a common nor practical way of building TreePathes.
The original selection disappears (no highlighting) but the new one selected does not Under my assumption:
- the original selection disappears (because by construction the original selection's TreePath it is not equals() to the TreePath passed in argument to setSelectionPath(...)).
- no new selection is rendered (because by construction no TreePath in the JTree's model can be equals() to the TreePath argument).
Does anybody have an idea of what may be going wrong ? The selection path is valid as I have verified it with the debugger.Under my assumption:
- you may have verified that the TreePath seemingly contained the expected values (often rendered in a debugger using toString() calls)
- you may have overlooked that the TreePath components were not the same references.
- you may not have executed step-by-step the TreePath.equals() methods nor the equals() method of the path's components.
Keep in mind that this is just an assumption, based on your code fragment (and on prior painful experience with JTree). If i'm off base and you still need help, please post an SSCCE as sugested previously.
Edited by: jduprez on Oct 11, 2009 12:53 PM