How to mimic the listView stickey-items like on Lollipop's contacts app?

Question

Background

Google has recently published a new version of Android, which has a contact app that look like this :

Answer 1

Well the source code of the app is always a good place to start

• https://github.com/android/platform_packages_apps_contacts/tree/master/src/com/android/contacts
• https://android.googlesource.com/platform/packages/apps/Contacts/