Init'd AndroidJavaClass with null ptr

I am facing this issue kindly help me what the meaning of this .

I faced that error too just now.
I searched google, blogs, communities and so on… but many people said it’s just things that we can see run in the editor. Please do try run by android device.
if you want to run in editor
do add this code.
public static AndroidJavaClass AdClass;

        AdClass = new AndroidJavaClass("");