Is cpp that needs to call java should be placed in jni folder?

cocos2d-x C++
#1

is cpp in Classes unable to use jni?

#2

trying http://www.cocos2d-x.org/wiki/EasyNDK
(EasyNDK for Cocos2d-x v3.0)
for cpp call java/obj-c and vice versa

#3

The C++ code in Classes is supposed to be shared between all platforms, and as such shouldn’t call any platform-specific code.

What you should do is expose the header in Classes, and then do the C++ implementation in platform-specific code. For Android, that means adding a cpp file in jni folder (which is the convention, you can put it somewhere else if you like, and even do the implementation in Classes with platforms macro, but it’s not practical).