Well, yeah, I guess you could. The software on the tills I use at work are coded in Java, and are all linked to a big database in Hemel Hempstead; there's your network programming for starters.
If you are planning a career in this, you may be as well to learn a bit of C as well - this is the language that Java (and most other programming languages, come to think about it) is based on. It should be pretty easy to pick up if you know your Java. You'll avoid C like the plague generally, but for lower level tinkering or for speed-critical apps it's something pretty handy to know.
