Using GSON to parse a JSON array

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"
    }
]

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

Problem is caused by comma at the end of (in your case each) JSON object placed in the array:

{
    "number": "...",
    "title": ".." ,  //<- see that comma?
}

If you remove them your data will become

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

and

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

should work fine.

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);