AsyncTaskLoader vs AsyncTask

Since Honeycomb and the v4 Compatibility Library it is possible to use AsyncTaskLoader. From what I understand, the AsyncTaskLoader can survive through config changes like screen flips.

Is it recommended to use AsyncTaskLoader instead of AsyncTask? Does LoaderManager get in the picture too?

But I haven't found any good example(s) about how to correctly use the AsyncTaskLoader. The docs also provide no examples. Can anyone provide some good examples.

Solution 1:

You can have a look at the compatibility library's source code to get more info. What a FragmentActivity does is:

• keep a list of LoaderManager's
• make sure they don't get destroyed when you flip your phone (or another configuration change occurs) by saving instances using onRetainNonConfigurationInstance()
• kick the right loader when you call initLoader() in your Activity

You need to use the LoaderManager to interface with the loaders, and provide the needed callbacks to create your loader(s) and populate your views with the data they return.

Generally it should be easier than managing AsyncTask's yourself. However, AsyncTaskLoader is not exactly well documented, so you should study the example in the docs and/or model your code after CursorLoader.

Solution 2:

When compare AsyncTaskLoader vs. AsyncTask, as you may know when you rotate your device screen, it may destroy and re-create your activity, to make it clear let image rotate your device while networking transaction is going on:

AsyncTask will be re-executed as background thread again, and previous background thread processing was just be redundant and zombie.

AsyncTaskLoader will be just re-used basing on Loader ID that registered in Loader Manager before, so avoid re-executing network transaction.

In summary, AsyncTaskLoader prevent duplication of background threads and eliminate duplication of zombie activities.