Generate Class Diagram Using Eclipse explains step by step details of installing and configuring ObjectAid plugin with eclipse, this plugin will automate the generation of Class Diagram and Sequence Diagram from java source code.
You need to remember one thing that for generating Sequence Diagram, you need a valid licence. But for generating Class Diagram, it is free.
ObjectAid UML Explorer is an agile and lightweight code visualization tool for the Eclipse IDE.
It shows your Java source code and libraries in live UML class and sequence diagrams that automatically update as your code changes.
Reference -> http://www.objectaid.com/home
You need to download
You can install the ObjectAid UML Explorer Eclipse plugin using Eclipse update manager from the following links
ObjectAid UML Explorer Installation
For Installing ObjectAid Plugin from eclipse, select Help->Install New Software Then click add, then provide Name and Location according to the following screenshot
Then select the ObjectAid class diagram plugin it is a free tool, Sequence diagram plugin requires a valid licence, click next and accept the license details, it will install the ObjectAid plugin for generating class diagram