How to import contacts from Facebook into my android app?

I want to make an android app that enables the user to log in to his facebook account and then it imports all the contacts from his facebook profile and displays it in my app. So far I have completed the logging in part. How do i make a graph API request to get the contacts? I've been looking everywhere but unable to get a detailed description of how to go about it. I'm using facebook sdk version 4.0.0