I did exactly same thing… same error. I downloaded cocos2dx 3.15 and opened cpp-empty-test android studio project till here no problem, I’m able to compile, run and debug. After adding my classes, resources and updating Android.mk file only giving problem. Gradle build failed. I did all this in Ubuntu. Please look into this issue.
any solution? i get error
Execution failed for task ‘:example2:externalNativeBuildDebug’ cocos2d
i just create new project, then compile, then get that error
Solved. I can compile with NDK r14b 
Hi,
I have a problem, when I run my app from Android-studio it works perfectly fine, however when I install the resulting apk the app crashes. The error contains something like: (Didn’t find class “org.cocos2dx.cpp.AppActivity” ), which means it isn’t able to find the activity class. How can I solve this problem?
Thanks
Can you share your configuration with a successful debug? Maybe a how to?