In your other thread you had asked about using the MutableTreeNode. This is my response:
The MutableTreeNode is a node on a tree. You should read the tutorial I mentioned in the other post. It has a section about using TreeModels, and the DefaultTreeModel. Even if you aren't using the JTree for display purposes it may be a good structure to look over for representing non-binary tree structures.
It really is just a bunch of links between nodes (parent and lists of children) with identifiers for leaf nodes.