This is an implementation of a Red-Black Tree in Java: http://en.wikipedia.org/wiki/Red%E2%80%93black_tree A red.black tree is a type of self-balancing binary search tree, a data structure used in computer science, typically to implement associative arrays. I used this to store a large set of data that had to be "auto completed" over, and I didn't have the option to use a database. This guaranteed that the height of the tree stayed sane. This uses Java generics so it can be applied to any object.