Introducing dividers

In order to introduce dividers into the claim overview screen, you'll need to run a second pass over the data being delivered from the Room database layer, and figure which items require a divider. This should be done on a background worker thread, so that larger datasets won't impact the user experience. Let's get to work and add some simple dividers to the travel claim app to appear between claim items made on different days; this will require some major changes to how the ClaimItemAdapter class works. The most obvious change is that it will now have a List of DisplayItem objects instead of directly containing a List of ClaimItem objects.

Follow these steps to restructure the ClaimItemAdapter to use DisplayItem objects to mix both claim items and dividers in the RecyclerView:

1. First, you'll need a nice line that you can use as a divider. This will be a drawable that can be rendered using an ImageView widget. Right-click on the res/drawable directory and select New|Drawable...