ft_hangouts is an app to manage your contacts.
https://www.youtube.com/watch?v=dGFZ9sVIKuo
https://www.tutorialspoint.com/android/android_sqlite_database.htm
https://developer.android.com/training/data-storage/sqlite#java
https://www.javatpoint.com/android-sqlite-tutorial
https://www.tutorialspoint.com/android/android_list_view.htm