I'm having an issue updating my JTree when I add a node to the tree.

When I add to the JTree directly, I do the following (this method is
in my class that extends JTree)

public void addNode(DataModel parent, DataModel newChild) {
 // create new node and expand the path to show the node
 ((DataModel) parent).insert(newChild, parent.getChildCount());

 // if a successful addition
 if (newChild.getParent() != null &&
newChild.getParent().equals(parent)) {
  treeModel.addTreeModelListener(newChild);

  // update tree and scenario values
  newChild.updateScenarioModel();

  // make the tree an observer of the DataModel (and the DataModel's
  // children)
  this.addObservers(newChild);

  ((DataModel) newChild.getParent()).sort();
  this.updateUI();
}

DataModel implements MutableTreeNode and the root node is passed in to
the JTree on creation.

So, I'm basically adding everything directly to the JTree.  Honestly,
now that I think about it, that doesn't entirely seem right as the
JTree should be *just* a view.  So, I have been trying, instead, to
add to the node.  However, the JTree doesn't update or refresh when I
add the node.

I've been reading online, and there is a lot of discussion about
TreeModel's, but I am not sure if I entirely understand how this plays
into the TreeNodes or how they work together.

Any further explanation would be welcomed.  Thanks.