Android Studio cannot resolve symbol but code executes correctly

Question

I have recently created a library Jar file that I imported in my Android project. I am able to call functions and use classes that are present in this Jar file, but Android

Answer 1

This problem regularly generated in android 3.1. I have tried every possible way. But it resolved when i delete .gradle and .idea file and start Android studio which is already close.

Android studio create .idea and .gradle file for your project again. After this click on sync project with gradle. Now everything works fine.