I am currently working on a project in Eclipse but the problem is that this project is very big (a lot of codes, classes, packages, etc) and undocumented. Since, the project is
I'd advise StarUML or StavrUML, the unofficial fork. It reverse engineers code compliant with Java versions before 1.6 or something. Yes, the project was abandoned years ago, but the UML editor remains incredibly strong and powerful.
However, I'd avoid using reverse engineering a UML diagram. You'll probably get an unreadable mess out if it. Just get stuck in and make it manually :)
I think MoDisco is what you are looking for ( here for a short intro)
I'm sure you can find a suitable tool for your needs if you check these.
It seems that the question is dealing with Eclipse plugin therefore Modisco and StartUML are not a possible choice because they are either not a graphical class diagram viewwer or an Eclipse plugin.
The tools that I have evaluated and selected are:
Topcased can reverse a project and gives an UML view. The reverse is good even if not recursive. I mean that you can detect only object having their own information such as class, interface, package, method and attributes but you can not detect calls between classes because this require a recursive reverse.
eUML will give you a visual class diagrams and the possibility to navigate but no model only EMF tags inserted inside your own code. I like the visual representation of the class diagram but having EMF tags in my code is too intrusive !!
You can try RSA which is a pretty good reverse having a real UML model but you will also get EMF tag in your code
The best for me and with no doubt is EclipseUML Omondo with no tag in the code and a high quality UML model but it is really too expensive !!