I reverse the java project and then just drag and drop from the Package Explorer to the diagram. When I have finished to present the existing classes I then add UML classes in the diagram. No code generation or model driven, just UML graphical representation mixing existing classes and abstract classes. I give my diagrams to the team and let them integrate it.
I am very lazy when modeling :-)
I can see my classes and navigate from one package to another showing associations, inheritances and dependencies dynamically. No need to create a diagram per view, I prefer to use the show hide links and directly navigate in the java code and model from the same diagram it is easier and a lot more powerful because interactive.
Just using the class contextual menu I can navigate. Really cool