Tukukkk

I am using gson to convert JSON to my POJO. If I am not passing a specific parameter (the whole parameter, not just the value) in my JSON, it is automatically initialized as null.
Is there a way to find out difference between the above null and the null I get, when I am passing that parameter value as null.

P.S. I cannot change the default conversion from JSON to POJO

use default value in your classes. When the field not pass in json string the value will be the default. example code like below.

public class User {

    private String name;

    private String age="not set";



    public String getAge() {

        return age;

    }



    public void setAge(String age) {

        this.age = age;

    }



    public String getName() {

        return name;

    }



    public void setName(String name) {

        this.name = name;

    }



    @Override

    public String toString() {

        return "User{" +

                "name='" + name + ''' +

                ", age=" + age +

                '}';

    }

}



public class GsonClient {

    public static void main(String args) {

        String usersJson = "[ { "name": "henry" }, { "name": "justin","age":null } ]";

        Gson gson = new GsonBuilder().serializeNulls().create();

        User usersWithAge = gson.fromJson(usersJson, User.class);

        for (User user : usersWithAge) {

            System.out.println(user);

        }

    }

}

output is here

User{name='henry', age=not set}

User{name='justin', age=null}

Object.keys(theObject) will contain the key if the value is set to null or undefined. Also theObject.hasOwnProperty(...) will let you know.

So convert the JSON to an object and inspect the keys to see if the value was marshalled as undefined, null, or not present.