JTree making a node act as parent

[John Jai]

Hi,

I want to make a node to reflect as a Parent node containing children (Means i need the "+" sign associated with that node when shown in JTree). Currently I am using the TreeSelectionListener interface to do some operation when a node is selected in the JTree. But I would like to do some operation only when the node is expanded using the TreeExpansionListener interface. At this point there is only a Root and say some 10 children under the root. I want all the 10 children to behave like a collapsed node (pretend they have some children within them).
Is there a way I can do this? If not how to use the TreeExpansionListener for a leaf node(bit awkward)?

[John Jai]

I did it by adding a dummy node and then removing it in the TreeWillExpandListener interface when a node is expanded.

[Rob Spoor]

Wouldn't it be easier to use a new TreeModel that returns false for isLeaf?

[John Jai]

Hey Rob!!! Thanks! it worked when the isLeaf() is overridden...

class HierarchyTreeModel extends DefaultTreeModel{
		public HierarchyTreeModel(HierarchyTreeNode rootNode){
			super(rootNode);
		}

		@Override
		public boolean isLeaf(Object node) {
			// TODO Auto-generated method stub
//			return super.isLeaf(node);
			return false;
		}
		
	}

Thanks Again!!!

[Rob Spoor]

You're welcome.

And the good thing is, this isn't even a trick or workaround - it's documented:

Returns true if node is a leaf. It is possible for this method to return false even if node has no children. A directory in a filesystem, for example, may contain no files; the node representing the directory is not a leaf, but it also has no children.