Android NDK OpenGL crashing -

i trying setup opengl using android ndk. followed along tutorials , reason when run project crashes , throws following warning:

.unsatisfiedlinkerror: no implementation found void projectname.androidgl.graphicsclass.init()

however code imports library:

system.loadlibrary("native-lib");

and if change name throws different error, , in file contains

jniexport void jnicall java_projectname_androidgl_graphicsclass_init(jnienv*) {     initializeopengl(); }

i feel should looking for. have specify functions expose?

edit: figured out. required add extern "c" before each function.

ANy