Android Programming: The Big Nerd Ranch Guide, 2nd Edition

Using AsyncTask to Run on a Background Thread

The next step is to call and test the networking code you just added. However, you cannot simply call FlickrFetchr.getUrlString(String) directly in PhotoGalleryFragment. Instead, you need to create a background thread and run your code there.

The easiest way to work with a background thread is with a utility class called AsyncTask. AsyncTask creates a background thread for you and runs the code in the doInBackground(…) method on that thread.

In PhotoGalleryFragment.java, add a new inner class called FetchItemsTask at the bottom of PhotoGalleryFragment. Override AsyncTask.doInBackground(…) to get data from a website and log it.

Listing 23.5  Writing an AsyncTask, part I (PhotoGalleryFragment.java ...