An example of using a custom View subclass with ListView and a custom Adapter.
ItemView encapsulates the pattern of:
- Creating a complex view for a list item
- Finding and populating child views with data (the "Holder" pattern)
- Associating a view with a model object
The ItemView class is a subclass of RelativeLayout that knows how to inflate its own children (from a separate layout file) during construction.
It has methods to access its child views by useful names (getTitleTextView()), but these methods are used only in the unit tests. It excels in its encapsulation of translating an Item into its views using setItem(Item).
The static inflate(ViewGroup) method encloses the private details of which layout should be used to create an instance of this class. The ItemAdapter relies on this to make instantiation as simple as one succint line of code.
This layout is used by the inflate(ViewGroup) method on ItemView to create a new instance, but it could also be used via an include tag elsewhere in another layout and work just as well. It intentionally avoids placing child views inside the ItemView, since that work is handled in the ItemView constructor.
This layout sets up the children of the ItemView at construction time. The merge tag at the root means that the children of it will be added directly as children of the ItemView. The resulting layout is efficient for both the programmer (little code required to use ItemView) and the rendering engine (no extra nesting or useless container layouts).
There are unit tests that cover ItemView, ItemAdapter and Item. If you have some good pointers on how to effectively test ItemListFragment, please get in touch. I tried, and it's non-trivial.