In .NET land I would normally query the database and populate a generic List kind of collection. Then the app would use this.
In Android land I have been reading about D
You can use the cursor for your adapter. Android is driven by listadatpers such as SimpleCursorAdapter. Using constant is a pro for design technique.
Is this to save on resources perhaps?
Exactly. + performance.
The general rule is to avoid creating objects w/o necessity as you are limited on memory, cpu power (and resulting battery life) and garbage collection is rather expensive.