JTree not scrolling to selected node

[johnsmit johnsmih]

I have easily looked at 30 sites (including this one) trying to find a solution to the problem of a JTree not scrolling to a selected node. My JTree, which is in a JScrollPane, does have the proper node selected and highlighted; but I cannot get the scrollpane to cooperate.

Most every site I have found (with entries going back to 2002) are all similiar to https://coderanch.com/t/334800/GUI/java/jtree-not-scrolling-selected-node, which prescribes calling either scrollPathToVisible(treePath) or scrollPathToVisible(row). I have also tried scrollRectToVisible(Rectangle) on the JViewport of the JScrollPane in which the JTree resides. I have also tried manually setting the value on the JScrollBar itself, all to no avail.

I cannot provide the full code; but here is the snippet and the output I receive.

Construction for my JTree:

      this.jtTree = new JTree( this.dtmTreeModel );
      this.jtTree.setEditable( false );
      this.jtTree.setDragEnabled( false );
      this.jtTree.getSelectionModel().setSelectionMode( TreeSelectionModel.SINGLE_TREE_SELECTION );
      this.jtTree.setShowsRootHandles( true );
      this.jtTree.setScrollsOnExpand( true );
      this.jtTree.setLargeModel( true );

      //
      // Possible line style values are "Angled", "Horizontal", and "None" ( the default ).
      //
      this.jtTree.putClientProperty( "JTree.lineStyle", "Angled" );
      this.jspATSTreeScrollPane = new JScrollPane( this.jtTree );

Upon starting up the application, I start a progress task, which loads the tree with nodes from a cache/database. After it completes, it calls a

setCurrentTreeNode()

method that successfully expands and selects the node (node is last node selected when shut down application). What it does not do is scroll to the selected node.

      //
      // Retrieve the last selected tree node
      //
      DefaultMutableTreeNode dmtnNode = this.getLastSelectedNode();
      if ( dmtnNode == null ) {
         return;
      }

      //
      // Now have node, so expand, select, and scroll to it.
      //
      TreePath tpTreePath = new TreePath( dmtnNode.getPath() );

      System.out.println( "setCurrentTreeNode():  Treepath:  " + tpTreePath );

      this.jtTree.expandPath( tpTreePath );
      this.jtTree.setSelectionPath( tpTreePath );
      int intStartingRow = this.jtTree.getRowForPath( tpTreePath );

      System.out.println( "setCurrentTreeNode():  Starting row:  " + intStartingRow );
      System.out.println( "setCurrentTreeNode():  this.jtTree.isVisible():  " + this.jtTree.isVisible() );
      System.out.println( "setCurrentTreeNode():  this.jtTree.isShowing():  " + this.jtTree.isShowing() );
      System.out.println( "setCurrentTreeNode():  is on EDT:  " + javax.swing.SwingUtilities.isEventDispatchThread() );

      //
      // This does not work.
      //      this.jtTree.scrollPathToVisible( tpTreePath );
      //

      //
      // Neither does this.
      //
      this.jtTree.scrollRowToVisible( intStartingRow );

The output from the System.out's above is:

   setCurrentTreeNode():  Treepath:  [MyRoot, MyParent, MyChild, MyGrandchild]
   setCurrentTreeNode():  Starting row:  9
   setCurrentTreeNode():  this.m_jtTree.isVisible():  true
   setCurrentTreeNode():  this.m_jtTree.isShowing():  true
   setCurrentTreeNode():  is on EDT:  true

There has to be something simple that I am missing or not understanding, but, like I said, I have tried solutions on at least 30 sites and nothing has worked.

Can anyone point me to what might be causing the problem? I mean, I have tried manually setting the vertical scrollbar value and even THAT did not work.

Thank you in advance for your response.

[Christophe Verré]

"johnsmit johnsmih",
You have received a Private Message from one of the ranch's moderator. Did you read it ?

[Michael Dunn]

> I cannot provide the full code;

we don't want it.

start another project
add a simple JTree() - empty constructor (will give you nodes of colors/sports/food)
try scrolling to (pre) selected node
if it works, replace this
"Upon starting up the application, I start a progress task, which loads the tree with nodes from a cache/database."
with some hard coded data - just a few items
recompile, try again
if it still works OK, add one line at a time of these tree changes
this.jtTree.putClientProperty( "JTree.lineStyle", "Angled" );

when you get to the point of it not working, post that code (all of it, so we can copy/paste/compile/run/observe)

[johnsmit johnsmih]

Thanks for the exercise, it helped find the problem. I was setting the tree node before it was added to the scroll pane. As expected (and documented), calling scrollRowToVisible() at that point did nothing, since it was not in a scrollable pane. Putting the setCurrentNode just after adding to the scroll pane immediately fixed the issue.

Sorry to have bothered the reader(s) and thanks again.