That's a pretty astonishingly limiting question, but I would recommend that you go for Java, if you're only going to do one systems language. As a new programmer, (which I assume you must be) the "power user" features of C++ (pointer arithmetic, templates, operator overloading) are going to be more confusing than useful.

Really, though, if you only have time to learn one language, make it something you can get some real use out of early on, like Python, PHP, or Ruby. Learning C++ or Java alone could be more of an exercise in masochism than anything else.

Without more details on what you want to do, it is hard to say. And if it is your first language, probably that none of them is a good choice. Why limit the choice to these two languages?

As far as learning something worthwhile is concerned, I'd recommend sticking to the subset of C++ used in Kernighan's "The Practice of Programming".

Sounds like you've got a couple of job offers on the table, or some interviews lined up? If not, why this choice of language?