Just in case you've not seen this package, picamera is a Python library for accessing the camera on a Pi. I haven't used it but the author seems to like it.
http://picamera.readthedocs.org/en/release-0.8/
I'm just curious why you would run Java on a Pi? It seems awfully resource heavy. C or even Python would appear to be much better manager of resources. Just wondering.
Jim.
PS we're using C++ and raspistill in signal mode to grab parts of the cameras FOV for pattern matching. FYI.