Heh, making a galaxian in C++ is a nice training idea 
But if it is a simple game like that, yeah, java will be much easier to do so. C++ is a very deep programming language for newbie game programming, it can get confusing since it can be used in almost all the programming paradigms (procedural, Abstract data types, Object oriented programming). But if you can proficiently program in C++, you can program in any language that exist today. Infact, most of the Java language syntax is based on C++, minus all the trouble with pointers, memory handling and stuff.

But if it is a simple game like that, yeah, java will be much easier to do so. C++ is a very deep programming language for newbie game programming, it can get confusing since it can be used in almost all the programming paradigms (procedural, Abstract data types, Object oriented programming). But if you can proficiently program in C++, you can program in any language that exist today. Infact, most of the Java language syntax is based on C++, minus all the trouble with pointers, memory handling and stuff.