When I'd to choose java over c++ ??

Answer 1

The platform you plan to develop on dictates the programming language that you choose. Java and C++ are used for different purposes, i.e. Java commonly used for developing Android apps, C++ used to built operating systems and cross-platform desktop games.

I wouldn't say that Java is dying though. Just look at Objective-C.

Answer 2

When your boss asks you to. It is a dying language. It is easier to program than c++, so if you don't care about the sluggish speed, then Java is better than c++.