I got some experience on Joomla and I like their community and Joomla's plug and play. They have a lot of tested components working well. I remember my first steps: easy to start and the only requirements are good old Apache and PHP. On the other hand my only - but massive - complaint is I have to use PHP. I cannot get comfortable with PHP since I know the benefits of Java as a proper designed and very rich programming language. So I have been searching around for some days now and found really a lot of stuff out there. I have learned that there exist too many Java frameworks to be able to test them on my own. I think wicket and Stripes are good frameworks but I miss the easy-to-use. Wicket claimed to be "easy" but in the very first attempt I found myself got stucked in Maven and how to configure it and how to integrate it in Eclipse and what versions I need and so on. Of course there is no free lunch and I always need to learn some basics ... but I did not found anything like Joomla but Java based. For sure I am not the first person looking for such a solution, but till now I did not found it. Any comment is welcome! Thank you for reading!
Joomla is a CMS and Stripes and Wicket are not. So they do not compare well. The answers to this question might be helpful.
We're on the same situation.. I have been exposed to joomla for quite some time, but can't get comfortable with php since as you have mentioned.. java is really a properly designed language.
dotCMS if im not mistaken is a javabased cms..
I have been trying to generate static pages with joomla through java. I've tried to use its existing db in order to generate static pages. But the thing about it.. is that you need to view joomla's architecture as modular
if we're talkinng about joomla framework, MVC is of course one answer.. as of the moment, a number of MVC java web frameworks are currently popular (struts.. spring, etc)
I hope that helps.