Converting JSON to Java object using Gson

Question

I am trying to convert JSON string to simple java object but it is returning null. Below are the class details.

JSON String:

   {\"menu\": 
    {\"id\":          


        

Answer 1

Your JSON is an object with a field menu.

If you add the same in your Java it works:

class MenuWrapper {
    Menu menu;
    public Menu getMenu() { return menu; }
    public void setMenu(Menu m) { menu = m; }
}

And an example:

public static void main(String[] args) {
    String json =  "{\"menu\": {\"id\": \"file\", \"value\": \"File\"} }";

    Gson gson = new Gson();
    MenuWrapper m = gson.fromJson(json, MenuWrapper.class);
    System.out.println(m.getMenu().getId());
    System.out.println(m.getMenu().getValue());

}

It will print:

file
File

And your JSON: {"menu": {"id": "file", "value": "File", } } has an error, it has an extra comma. It should be:

{"menu": {"id": "file", "value": "File" } }

Answer 2

What I have found helpful with Gson is to create an an instance of the class, call toJson() on it and compare the generated string with the string I am trying to parse.