Volley: make request with List<T> in JSONObject

Question

I use Volley and need send to server list of objects User and List<Integer>.

User class:

public class User {

        public int id;
        public String name;

        public MyClass(int id, String name){
            this.id = id;
            this.name= name;
        }
}

I use code

    HashMap<String, Object> params = new HashMap<>();

    List<Integer> categories = new ArrayList<>(Arrays.asList(5, 8, 9));
    List<User> users = new ArrayList<>(Arrays.asList(
            new User(1, "User1"),
            new User(2, "User2"),
            new User(3, "User3")
    ));


    params.put("categories", categories);
    params.put("users", users);

    JSONObject jsonBody = new JSONObject(params);

The problem is JSONObject can't parse User

{
    "users": [
        null,
        null,
        null
    ],
    "categories": [
        5,
        8,
        9
    ]
}

How to parse it with JSONObject?

Parameter "users" should be array not string.

I need JSONObject because Volley use it

JsonObjectRequest(int method, String url, JSONObject jsonRequest,
            Listener<JSONObject> listener, ErrorListener errorListener)

Full code:

package com.example.admin.testjson;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;

import org.json.JSONObject;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Map<String, Object> params = new HashMap<>();

        List<Integer> categories = new ArrayList<>(Arrays.asList(5, 8, 9));
        List<User> users = new ArrayList<>(Arrays.asList(
                new User(1, "User1"),
                new User(2, "User2"),
                new User(3, "User3")
        ));


        params.put("categories", categories);
        params.put("users", users);

        JSONObject jsonBody = new JSONObject(params);


    }
}


package com.example.admin.testjson;


    public class User {
        int id;
        String name;

        public User(int id, String name){
            this.id = id;
            this.name = name;
        }
    }

Answer 1

I think you should replace MyClass by User in User class like this

public class User {

    public int id;
    public String name;

    public User(int id, String name){
        this.id = id;
        this.name= name;
    }
}

I have tested building JSONObject with your code, the users not null!

UPDATE:

Try use my following code for your new blank project (my project runs normally, users not null):

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    HashMap<String, Object> params = new HashMap<>();

    List<Integer> categories = new ArrayList<>(Arrays.asList(5, 8, 9));
    List<User> users = new ArrayList<>(Arrays.asList(
            new User(1, "User1"),
            new User(2, "User2"),
            new User(3, "User3")
    ));


    params.put("categories", categories);
    params.put("users", users);

    JSONObject jsonBody = new JSONObject(params);
    Log.i("BNK", jsonBody.toString());
}

public class User {

    public int id;
    public String name;

    public User(int id, String name){
        this.id = id;
        this.name= name;
    }
}
}