there is no such thing as Java Programming for linux
java programming is platform independant so wheter u write it on windows, linux or mac or whatever it'll run on any platform that has a java virtual machine so that alone makes it something great imo
the thing with java apps is that it's mostly the startup time that's slow (allthough Swing doesn't help either)
but seeing as how cpu's are getting more powerful each day the slowness of java is actually not that big of a deal anymore. Java is EXCELLENT for web-based apps (i'm not talking about applets). it's slower than php, but the speed of java web-apps is actually surprisingly well.
for my internship i had to write a system with java servlets and i can tell u it's great to work with. the servlets were running on a 400Mhz machine and when u opened the app in ur browser it was actually fast.
the language is very easy, well documented, safe, stable and it can do sooooooooooooooooooooooo much.
so besides of it being slow, java has nothing but advantages