APIviz is a JavaDoc doclet which extends the Java standard doclet. It generates comprehensive UML-like class and package diagrams for quick understanding of the overall API structure.
The ObjectAid UML Designer is optimized for the creation of UML class diagrams from existing Java source code and libraries within the Eclipse IDE. It was created to fulfill needs that no other UML tool seems to address...
MaintainJ, an Eclipse plug-in, generates sequence and class diagrams for a given use case, helping the users to quickly understand a complex Java or J2EE application.