JTree Important Question

Question

Hi All,
in the JTree, is there a way to change the root handles
icons, not through the UIManager?
I need the Changes to apply only for the one instance.
is there a key for the putClientProperty method?
a work around through the TreeCellRenderer is possible to
write, but seems as a bit of a waste.
10x in advance

Answer 1

OK. If "handle" means the leftmost icons, that is the little circle with a dash pointing right or down under Java L&F, or either a + or a - in a square under Windows & Motif L&F, they are NOT part of the node display, and so they are not dealt with by a renderer. They are completely L&F dependant (while the leaf, open, closed are renderer dependant, and the L&F just provides some "hint" to the default renderer). It is possible that some L&F would display trees in a completely different way, without handles. So this is the tree UI delegate business, not the renderer's.
You can set the icons for the application globally by setting UIManager properties Tree.expandedIcon and tree.collapsedIcon. (you knew that already). The good news is that the UI delegate seems to get these icons once sometime when it is created, rather than asking the UIManager each time it needs them.
I tried
    Object previousExpanded = UIManager.put("Tree.expandedIcon", myExpandedIcon);
    Object previousCollapsed = UIManager.put("Tree.collapsedIcon", myCollapsedIcon);
    tree2 =  new JTree(data);
    UIManager.put("Tree.expandedIcon", previousExpanded);
    UIManager.put("Tree.collapsedIcon", previousCollapsed);.
There is a tree1 created before and a tree3 afterwards, and it works fine, that is only tree2 get my icons.
I tried to go a little farther, as I am not sure when the ui delegate might get reset. So I wrote a descendant of JTree to do the job in updateUI.
public class CustomHandleTree extends JTree {
  // republish ancestor non-default constructors
  Icon expanded = null;
  public void setExpandedIcon(Icon anIcon) {
    expanded = anIcon;
    updateUI();
  // do the same for collapsed
  public void updateUI(){
    Object defaultExpanded = null;
    if (expanded != null)
      defaultExpanded = UIManager.put("Tree.expandedIcon", expanded);
     // collapsed stuff too
     super.updateUI();
    if(expanded != null)
      UIManager.put("Tree.expandedIcon", defaultExpanded);
     // collapsed stuff too
}It works too, and I can even set the handles dynamically, when clicking on some button. It refreshes properly.
The bad news is that I found that by trial and error, and have no single line of documentation to explain why it should work.
Hope it helps nevertheless.
Regards.