Single Use Loader

Question

In the click handler for a button, I'm loading some data from a content provider (using getContentResolver().query(...)), then sending that data off in a network request. Since the query happens on the main thread with this approach, I want to move this off the main UI thread.

I think I can use a LoaderManager, and fire off the network request in onLoadFinished(), but the problem is that I don't want onLoadFinished() called ever again (for that Loader id), because I don't want to fire the network request again, during a screen orientation for example.

So, how do I use a LoaderManager for a query that I only want to happen only once?

Answer 1

Calling LoaderManager#initLoader() in your Activity#onCreate() method will either create a new Loader and force a new load, or reuse an existing Loader and deliver the most recently queried data if any exists. So as long as you are using the LoaderManager correctly (i.e. the way the developer's site recommends in the documentation), you shouldn't have any problems.

Answer 2

In your onLoadFinished(), you can call getLoaderManager().destroyLoader(loaderId) (or getSupportLoaderManager() as applicable). That will stop the Loader from automatically reloading. You may also need to ensure that where you are calling initLoader is guarded from executing again (via saving a boolean variable in onSaveInstanceState for example).