JSON Object Containing Array To ArrayList<POJO> With GSON

Question

I am new to JSON and GSON, and I am taking a JSON feed from an input stream, and put it into an array list of custom objects. The JSON feed contains a single object, which contains an array of more objects. It looks something like this:

{ "container":[
    {"item_1":"item one"},
    {"item_2":"item two"},
    {"item_3":"item three"}
]}

I am currently using a TypeToken with a Map to obtain the container object along with the list of objects as an array list of custom objects. Like so:

InputStreamReader input = new InputStreamReader(connection.getInputStream());

Type listType = new TypeToken<Map<String, ArrayList<Item>>>(){}.getType();
Gson gson = new GsonBuilder().create();
Map<String, ArrayList<Item>> treeMap = gson.fromJson(input, listType);
ArrayList<Item> objects = treeMap.get("container");

input.close();

I would like to know if there is a way to skip the step of creating a Map<String, ArrayList<Item>>, and go directly from the input stream to an ArrayList<Item> using GSON. Just to consolidate my code, creating a map seems like an unnecessary step.

andersschuller · Accepted Answer · 2015-10-31 12:06:38Z

1

One option is to define a wrapper type which has a container property, and then deserialize the JSON to that type instead of to a Map.

public static class Wrapper {
    public List<Item> container;
}

Wrapper wrapper = gson.fromJson(input, Wrapper.class);
List<Item> objects = wrapper.container;

answered Oct 31, 2015 at 12:06

andersschuller

14k2 gold badges45 silver badges33 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bryan Over a year ago

Would this approach be any more efficient? It essentially gets rid of the need for a TypeToken, but you need to create another class. It looks like a good alternative, but not exactly what I was hoping for.

Collectives™ on Stack Overflow

JSON Object Containing Array To ArrayList<POJO> With GSON

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related