Question

I’ve a json output which returns something like this :

[
 {
  "title":"facebook",
  "description":"social networking website",
  "url":"http://www.facebook.com"
 },
 {
  "title":"WoW",
  "description":"game",
  "url":"http://us.battle.net/wow/"
 },
 {
  "title":"google",
  "description":"search engine",
  "url":"http://www.google.com"
 }
]

I am familiar with parsing json having the title object, but i’ve no clue about how to parse the above json as it is missing the title object. Can you please provide me with some hints/examples so i can check them and work on parsing the above code?

Note : I’ve checked a similar example here but it doesn’t have a satisfactory solution.

Answer 1

Your JSON is an array of objects.

The whole idea around Gson (and other JSON serialization/deserialization) libraries is that you wind up with your own POJOs in the end.

Here’s how to create a POJO that represents the object contained in the array and get a List of them from that JSON:

public class App 
{
    public static void main( String[] args ) 
    {
        String json = "[{\"title\":\"facebook\",\"description\":\"social networking website\"," +
            "\"url\":\"http://www.facebook.com\"},{\"title\":\"WoW\",\"description\":\"game\"," +
            "\"url\":\"http://us.battle.net/wow/\"},{\"title\":\"google\",\"description\":\"search engine\"," +
            "\"url\":\"http://www.google.com\"}]";

        // The next 3 lines are all that is required to parse your JSON 
        // into a List of your POJO
        Gson gson = new Gson();
        Type type = new TypeToken<List<WebsiteInfo>>(){}.getType();
        List<WebsiteInfo> list = gson.fromJson(json, type);

        // Show that you have the contents as expected.
        for (WebsiteInfo i : list)
        {
            System.out.println(i.title + " : " + i.description);
        }
    }
}

// Simple POJO just for demonstration. Normally
// these would be private with getters/setters 
class WebsiteInfo 
{
    String title;
    String description;
    String url;
}

Output:

facebook : social networking website
WoW : game
google : search engine

Edit to add: Because the JSON is an array of things, the use of the TypeToken is required to get to a List because generics are involved. You could actually do the following without it:

WebsiteInfo[] array = new Gson().fromJson(json, WebsiteInfo[].class); 

You now have an array of your WebsiteInfo objects from one line of code. That being said, using a generic Collection or List as demonstrated is far more flexible and generally recommended.

You can read more about this in the Gson users guide