I presume it was lightly-obfuscated using something like
ProGuard. As applications go, Starsector is pretty lightly obfuscated and Alex has been a lot more open than most developers to letting people poke at the source from the outside, which I applaud (it makes it easier for those of us with similar backgrounds to hunt down issues, among other things).
A philosophical note here. If you're not reliant on a
really novel method or technology and aren't deploying to a space where the application's security is paramount (say, an online game where you don't want people to attack the application to gain unfair advantages), I wouldn't fret about these issues very much.
Basic obfuscation of class / method / variable names will keep out most people, because if they weren't lazy, they wouldn't be trying to steal your code in the first place; very little in a typical game application is novel or new technology. The biggest issues that I know Alex has had to confront have been with people stealing the artwork for the game, frankly, not the code.