This article describes a simple Java tool called Xref which provides such capabilities, and some others beyond that as well. This tool demonstrates the benefits of the new ease-of-development features that have been added to the upcoming J2SE 5.0 release (“Tiger”). The main features used here are generics, typesafe enums, and other language extensions like the enhanced for loop for collections.

Read about it here:
http://java.sun.com/developer/technicalArticles/J2SE/xref/