JAVA borrows heavily from C++ syntactically; loosely, you could even call it a superset of C++ (though JAVA folk tend to get their panties in a bunch over that statement -- largely why I write it). Functionally, however, I'd call it more of a subset of C++. But, I'll try to stick away from my personal prejudice of the language.
JAVA is a platform independent language. Rather than being compiled into machine-dependent language like C++ is, it is compiled into JAVA bytecode (which has to be interpreted in some way or another). Normally, that bytecode is interpreted by a JVM (which is slow as hell). Most big platforms have methods of compiling or interpreting JAVA bytecode into native machine code, which makes the performance somewhat comparable to C++.
I would say JAVA is a lot like a C++ that goes out of its way to hide memory management from the programmer. This has its pros and cons.
* You don't have to manage your memory; as soon as a class is dereferenced it will eventually be cleaned up by the garbage-collector. This has minor performance implications. Technically, you can implement automatic garbage collectors for C++, but I've not seen a C++ programmer bother doing so.
* JAVA, also doesn't have pointers (ie, memory addresses). Not a surprising casualty in JAVA's war against memory management. It's not a huge deal, though, anything you can do with pointers is probably easily doable with one of JAVA's various class constructs. That is arguably a good thing, pointers are one of, if not the largest culprits in faulty software.
Basically, JAVA is a great choice for an academic language. It's virtually impossible to shoot yourself in the foot with it. It has a standard, and actually adheres to it. It has a great library set. It is more readable that C++. It is platform independent. And it is an OOP language.
And as for "will it help me develop in the future", it would. JAVA has grown quite popular in the last few years. I'd say there's more JAVA jobs in my area than C/C++ ones, in fact. Even if you don't program in JAVA later in life, any programming experience makes you a better programmer.
That being said, I wouldn't use JAVA for PPC game development personally, but I'm sure some people do (presuming there is ways to run JAVA apps on PPC).
I should also mention that intro Computer Science classes _should_ be mostly language independent. You'll just be learning your basic sorts algorithms, program-flow structures, and so on. So it really doesn't matter that much what language you're learning with.
