Using GSON to parse a JSON array

Question

I have a JSON file like this:

[
    {
        "number": "3",
        "title": "hello_world",
    }, {
        "number": "2",
        "title": "hello_world",
    }
]

Before when files had a root element I would use:

Wrapper w = gson.fromJson(JSONSTRING, Wrapper.class);

code but I can't think how to code the Wrapper class as the root element is an array.

I have tried using:

Wrapper[] wrapper = gson.fromJson(jsonLine, Wrapper[].class);

with:

public class Wrapper{

    String number;
    String title;

}

But haven't had any luck. How else can I read this using this method?

P.S I have got this to work using:

JsonArray entries = (JsonArray) new JsonParser().parse(jsonLine);
String title = ((JsonObject)entries.get(0)).get("title");

But I would prefer to know how to do it (if possible) with both methods.

Answer 1

public static <T> List<T> toList(String json, Class<T> clazz) {
    if (null == json) {
        return null;
    }
    Gson gson = new Gson();
    return gson.fromJson(json, new TypeToken<T>(){}.getType());
}

sample call:

List<Specifications> objects = GsonUtils.toList(products, Specifications.class);

Answer 2

Problem is caused by comma after last element of your array (after each title). If you remove it and change your data to

[
    {
        "number": "3",
        "title": "hello_world"
    }, {
        "number": "2",
        "title": "hello_world"
    }
]

Wrapper[] data = gson.fromJson(jElement, Wrapper[].class); will work fine.

Answer 3

Gson gson = new Gson();
Wrapper[] arr = gson.fromJson(str, Wrapper[].class);

class Wrapper{
    int number;
    String title;       
}

Seems to work fine. But there is an extra , Comma in your string.

[
    { 
        "number" : "3",
        "title" : "hello_world"
    },
    { 
        "number" : "2",
        "title" : "hello_world"
    }
]