You are using the C variant, but are compiling with g++, which invokes the C++ compiler (even if your source file has a .c extension).

Either change the C variants like

[code lang=”c”]
(*env)->FindClass(env, …)
[/code]

to the C++ variants, like

[code lang=”c”]
env->FindClass(…)
[/code]

or switch your compiler to gcc to compile the source as C code.

Note :- Took reference from here.