Please do not get me wrong, I skimmed the article and am bothering to reply here because I am interested. My following comments are meant as constructive criticism.
If you type "Eclipse UML plugin" into Google you will get many options, many free. All I have to do is highlight a Java package, click on a menu option and BOOM, I have a diagram of the code integrated into my IDE.
If I used your tool I would have to open up an independent application out of my IDE, which would be cumbersome whereas using a plugin for my IDE would be not.
similar to UML
I would prefer UML. I like standard tools and conventions. That way when I invest my time learning a system I can keep that investment ( and build on it ) when I go from tool to tool, project to project, job to job.
Most Java developers out of school and working on large projects work in IDEs. Your tool might have a better chance if it came as a plugin for Eclipse ( one of the most popular IDEs for Java, and it hosts other languages ) and used UML instead of your home grown diagramming system.
Good Luck