I did this project in an attempt to clear my basics for the below mentioned terms and how they interact with each other. The app contains a custom ContentProvider to store data entries from user. The table just has columns _ID | Name Uses a RecyclerView to display the data from the ContentProvider using Loaders. Also has couple of buttons to be used for update/delete data on the ContentProvider using SQLiteOpenHelper and ContentResolver.

ContentProvider provides the extra level of abstraction over your data to make it easier to change internally. Able to re-use the same standard API for accessing data rather than littering your code with low-level access to the database. Also works well with SyncAdapters and Loaders

This the actual Database accessor which is used inside ContentProvider methods insert/update/delete/query to access data from sqlite db storage.

The client api, which is used to access the ContentProvider from an app. An app only access the data from storage through ContentResolver

Loader is a class offered by the Android Framework. It loads data in a background thread and offers a callback interface to allow you to use that data once it's loaded. We use the Loader together with a database cursor. Loaders are usually a better way to call the query() method on the ContentProvider to keep updating RecyclerView as the data is inserted/updated on the provider.

The call stack looks like :

App -> ContentResolver.query() -> ContentProvider.query() -> SQLiteOpenHelper.query() -> SQLite DB


Query() -> Use Loaders if you need automatic notifications for data updates.
Insert/Update/Delete -> Use ContentResolver methods for these operations

Note: Query() can also be used with Resolver method for one time uses. But if you are populating recyclerviews and need auto updates use loaders.

While Loaders take care of fetching data on a background thread and not blocking the main thread. One should try to perform other operations like insert on a background thread too. AsynQueryHandler provides a mechanism to perform these on a different thread and provide a callback on the the main thread once the operation is completed.

Used for displaying the data from the ContentProvider. Its a replacement for the older ListViews. I have used Loaders along with RecyclerView to get automatic updates on UI, if data is added/updated/deleted on the ContentProvider.

Note: Had to integrate some of the Loader functionality in the RecyclerView adapter for it to react accordingly when it receives datachange notifications from the loader, so that the adapter can update the view/rows accordingly. See: DataViewerAdapter.java for changes.