Change or add theme to Android Studio?

For Change :-
File->Settings->Editor->Colors & Fonts-> In scheme name select Darcula and apply to see a awesome dark background theme editor.

For Add :-

You can download new themes from http://ideacolorthemes.org/

Once you have downloaded the .jar file, go to File -> Import Settings... and choose the file downloaded.

Android Studio theme change

Follow @amardeepvijay