This is an example that shows how add an iOS like A-Z Fast Scroll on the new RecyclerView released with Android L. Ready to compile in Android Studio.

• I am assuming that you already got an implementation of RecyclerView working. If not you can follow the example here: https://developer.android.com/training/material/lists-cards.html
• Replace android.support.v7.widget.RecyclerView with com.codecomputerlove.fastscrollrecyclerviewdemo.FastScrollRecyclerView
• Your adapter needs to implement FastScrollRecyclerViewInterface and override getMapIndex(). The function should return the mapIndex. Look into calculateIndexesForName() for inspiration on how to create it. Once created pass it to the adapter in the constructor.
• Create an instance of FastScrollRecyclerViewItemDecoration and add it on your RecyclerView

    FastScrollRecyclerViewItemDecoration decoration = new FastScrollRecyclerViewItemDecoration(this);
       mRecyclerView.addItemDecoration(decoration);

• add <dimen name="fast_scroll_overlay_text_size">100dp</dimen> to your /values/dimens.xml file. This is the dp size of the overlayed letter