I have a class BaseListAdapter, which inherits from ArrayAdapter. BaseListAdapter has some common setup code I use all the time, and then I inherit from BaseListAdapter for my individual datasources. On a ListActivity, when I cast the ListAdapter to ArrayAdapter, I have access to Add, Remove, NotifyDataSetChanged methods. When I cast it to BaseListAdapter or may final dataset type (say ItemDataSource), both of these do not have Add, Remove, and NotifyDataSetChanged appear in the intellisense. Is there a reason why? Is this a bug, or do I not have something setup correctly?