Android Studio can't find library classes after Gradle build

Question

I\'m trying to add a .jar library to my project into the /libs folder. Here is my grade.build:

    buildscript {
              


        

Answer 1

I had a similar situation where Android Studio couldn't find a library that definitely existed. Even though I was able to compile my project in Android Studio, run it from Android Studio in the emulator or on a physical device, and build it from the command line using gradlew, the Android Studio IDE complained Cannot resolve symbol 'ConstraintLayout'. I believe I had imported the library correctly because I followed Google's instructions: https://developer.android.com/training/constraint-layout/#add-constraintlayout-to-your-project.

Anyway, I ended up solving the problem as follows:

1. Close Android Studio
2. Delete the .idea folder in the project's directory
3. Open Android Studio
4. Re-import the project so Android Studio can regenerate the .idea folder

This in-fact solved the problem. I believe Android Studio somehow corrupted the .idea folder when I had done "Android Studio" > "Check for Updates" earlier in the day.