(My system is ubuntu 16.10)
This will make the android studio to find the adb-->
1)
Open with gedit: (ref:https://askubuntu.com/questions/127056/where-is-bashrc)
gedit ~/.bashrc
2)
Add this line to the bottom of your.bashrc and it works.
export PATH=$PATH:$HOME"/android-sdk-linux/platform-tools"
(ref: https://askubuntu.com/questions/652936/adding-android-sdk-platform-tools-to-path-downloaded-from-umake)
Restart the android studio
