包含数组的JSON对象到ArrayList <POJO> 与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.

Answer 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;