CursorLoader with Cursor accsss inside a loop

Question

I'm building a ListView, and each item in the ListView has data from several different Cursors. I've got an object which holds all the data for each item in the ListView. I'm using an ArrayList of these objects to populate the ListView.

The way I'm implementing it now, I first get a Cursor to all the rows in ContentProvider A. I loop through this cursor, adding three of it's fields to each object in the ArrayList. On each iteration of this loop, a new cursor is created to pull a field from ContentProvider B based on a field in ContentProvider A. This field is used to pull another field in ContentProvider C. So, essentially, there's lot's of Cursors being created, and the queries of subsequent Cursors are dependent on data from previous Cursors.

From what I understand, it is ideal to use CursorLoaders and LoaderManager to generate the Cursors in a separate thread and manage their life cycle correctly. I'm not sure how to translate this approach, or if there is in fact a better approach that minimizes the number of Cursors in the first place.

Answer 1

I think a simple CursorLoader is not the right solution in this case. I think you might have two possibilities:

• Use a CursorLoader for the first Cursor and use CursorLoader-chaining within your ListAdapter's getView() method. With CursorLoader-chaining I mean calling initLoader() in your onLoadfinished() method.
• Use an AsyncTaskLoader and create within your AsyncTask the object tree you need.

Of these two solutions I think the second is probably the better one - unless the list is very long. This is one area where ContentProviders fall short. You basically have to query n+1 (in your case n+2) times where one join should suffice.

If your list is very long, the second approach is not usable, your AsyncTask would take too long for users to accept it.

Should you ever hear of (or find yourself) of a better solution, please ping me here.