registerForContextMenu - Register View for a Context menu

Activity.registerForContextMenu was added in API Level
Registers a context menu to be shown for the given view (multiple views can show the context menu). This method will set the View.OnCreateContextMenuListener on the view to this activity, soonCreateContextMenu(ContextMenu, View, ContextMenuInfo) will be called when it is time to show the context menu.
Parameters: view - The view that should show a context menu.
(Long click)

1. Bind ArrayAdapter to ListView

2. Add to end of onCreate method. After it is registered the ListView to be eligible to create a context menu.
registerForContextMenu registers a context menu.

getListView() returns a ListView object that is used for the registration. 

registerForContextMenu(getListView());

Resources:
http://developer.android.com/reference/android/app/Activity.html#registerForContextMenu(android.view.View)
http://thedevelopersinfo.wordpress.com/2009/11/06/using-context-menus-in-android/