I had the same issue on a mac as well.

Open your /Users/macuser/ folder
Press CMD + SHIFT + . (dot/period) to view hidden folders
DELETE .gradle folder
Restart Android Studio
This will cause Android Studio to rebuild and re-download your .gradle folder fixing your corrupt files in the process.

NOTE* I'm looking for experienced programmers to let us know if this is safe / correct to do so! It worked for me with no errors but i'm new to this so a second opinion would be appreciated.