title: What java datastructure/library do you use for a Tree
body: <p>I have a Region Hierarchy(think State, District, Taluk, etc) that I need to represent using a Tree. I saw a few implementations of a Tree in the public domain BUT not sure how good they are and how well they are maintained. Apache Collections doesn't have one of those NOR do the google collections. I'm wondering if any of you can point me to an implementation of a Tree in Java(with generics).</p>
  
  <p>Thank you,</p>
  
  <p><strong>Update</strong>
  I am looking for a Tree Datastructure, preferably implemented using Generics : well tested.</p>