Wikipedia
Jikes
Jikes is an open source Java compiler written in C++. It is no longer being updated.
The original version was developed by David L. "Dave" Shields and Philippe Charles at IBM but was quickly transformed into an open source project contributed to by an active community of developers. Initially hosted by IBM, the project was later transferred to SourceForge. Among its accomplishments, it was much faster in compiling small projects than Sun's own compiler, and provided more helpful warnings and errors.