They say you have to use jni if you want to use java for robot programming. What is the native language for robot programming? Is it c/c++?
I was reading an article maybe a year ago about how a Mexican group of high school guys built an underwater robot from off the shelf computer parts. Maybe your local computer hardware shop would be a good starting point. Otherwise, some universities have microelectronics units that usually do some kind of robotics among other things. You might want to try your local university as well.