PATRICIA Trie
Practical Algorithm to Retrieve Information Coded in Alphanumeric
This is a general purpose implementation of a PATRICIA Trie in Java. It implements the SortedMap interface and integrates well with the Java Collections Framework. You can use any kind of Objects for Keys as long as they can be accessed bit-wise. You can find examples in the wiki and there is a blog post with some additional information about the implementation.
The PATRICIA Trie is also known under the names Radix and Crit Bit Tree.
Download: Binaries can be found on the project's Google Code Page.
NOTE: This implementation has been contributed to Apache Commons Collections and Google Collections Library.