on the Android developers' web site at http://developer.android.com/reference/a\\... Stepping through the code in this class, we can see that the first thing we do is set up a URL (#2). This URL makes up a query to the Picasa API. The Arguments state that we want to retrieve a maximum of 20 images that are of thumbnail size and relate to landscapes and sunsets. Also we state that we want the data to be returned in a JSON format. For the purpose of keeping things simple this URL is hard coded, but it is of course possible to build URLs that can make queries of many varying types at runtime. The constructor of LoadFeedData class take a reference to the Adapter for the ListView (#3), so that we can notify it when we have retrieved the feed data from the Picasa API. All the main work of this class happens in the doInBackground method. Here we use the private method retrieveStream (#4) to return an InputStream. The InputStream contains a serialized data object in a JSON format. To transform the JSON string into objects that we can work with, we use a class from the GSON library and call the method fromJson (#5) while passing the InputStream a class that we want the JSON data mapped into. To parse the JSON data we use GSON, which is library. The GSON library is a powerful way to deserialize data from existing JSON strings and can also be used to serialize objects