Android Studio E/dalvikvm: Could not find class… referenced from method

Question

I encountered a problem that seems to have something to do with the libraries in android studio.
I am having compiling errors like:

Could not fi

Answer 1

What I think solved the issues for me (after trying above suggestions) Shrink the code and use progaurd rules explained officially here

As I am novice to Android Studio, felt that my project, though a very small app, might be inflated by multiple experimental library inclusions + so many comments(and inactive code inside) causing 64K?(nopeIguess),illegitimate references(possibly!); just a intuitive guess after reading answer by @PKuijpers(thanks!). And honestly I didn't wanted to include multiDex because after also reading official document, I was sure that my app is not PokemonGo or NFS or big enough to qualify for multidex.