app:compileDebugNdk No rule to make target
If your android studio has some error message like :app:compileDebugNdk No rule to make target ... Error Code: 2
when you type some JNI
code.
This is a very very very strange problem. Because you need at least 2 jni file.
So..you must to create empty file (util.c)
in your jni folder.
Example: