如何在Android ListView一侧显示字母

I've looked at a lot of tutorials for making a ListView have the alphabetical letters on the side (like the Contacts list), but they all seem to using a ListActivity class and/or data from a database while I'm just using a ListView (no special Activity) and an ArrayList of data. Does anyone know how I can implement that alphabetical-scroll feature in the Contacts list for my own ListView? I've looked at a lot of tutorials for making a