[java] JSON order mixed up

I've a problem trying to make my page printing out the JSONObject in the order i want. In my code, I entered this:

JSONObject myObject = new JSONObject();
myObject.put("userid", "User 1");
myObject.put("amount", "24.23");
myObject.put("success", "NO");

However, when I see the display on my page, it gives:

JSON formatted string: [{"success":"NO", "userid":"User 1", "bid":24.23}]

I need it in the order of userid, amount, then success. Already tried re-ordering in the code, but to no avail. I've also tried .append....need some help here thanks!!

Real answer can be found in specification, json is unordered. However as a human reader I ordered my elements in order of importance. Not only is it a more logic way, it happened to be easier to read. Maybe the author of the specification never had to read JSON, I do.. So, Here comes a fix:

/**
 * I got really tired of JSON rearranging added properties.
 * Specification states:
 * "An object is an unordered set of name/value pairs"
 * StackOverflow states:
 * As a consequence, JSON libraries are free to rearrange the order of the elements as they see fit.
 * I state:
 * My implementation will freely arrange added properties, IN SEQUENCE ORDER!
 * Why did I do it? Cause of readability of created JSON document!
 */
private static class OrderedJSONObjectFactory {
    private static Logger log = Logger.getLogger(OrderedJSONObjectFactory.class.getName());
    private static boolean setupDone = false;
    private static Field JSONObjectMapField = null;

    private static void setupFieldAccessor() {
        if( !setupDone ) {
            setupDone = true;
            try {
                JSONObjectMapField = JSONObject.class.getDeclaredField("map");
                JSONObjectMapField.setAccessible(true);
            } catch (NoSuchFieldException ignored) {
                log.warning("JSONObject implementation has changed, returning unmodified instance");
            }
        }
    }

    private static JSONObject create() {
        setupFieldAccessor();
        JSONObject result = new JSONObject();
        try {
            if (JSONObjectMapField != null) {
                JSONObjectMapField.set(result, new LinkedHashMap<>());
            }
        }catch (IllegalAccessException ignored) {}
        return result;
    }
}

For those who're using maven, please try com.github.tsohr/json

<!-- https://mvnrepository.com/artifact/com.github.tsohr/json -->
<dependency>
    <groupId>com.github.tsohr</groupId>
    <artifactId>json</artifactId>
    <version>0.0.1</version>
</dependency>

It's forked from JSON-java but switch its map implementation with LinkedHashMap which @lemiorhan noted above.

The main intention here is to send an ordered JSON object as response. We don't need javax.json.JsonObject to achieve that. We could create the ordered json as a string. First create a LinkedHashMap with all key value pairs in required order. Then generate the json in string as shown below. Its much easier with Java 8.

public Response getJSONResponse() {
    Map<String, String> linkedHashMap = new LinkedHashMap<>();
    linkedHashMap.put("A", "1");
    linkedHashMap.put("B", "2");
    linkedHashMap.put("C", "3");

    String jsonStr = linkedHashMap.entrySet().stream()
            .map(x -> "\"" + x.getKey() + "\":\"" + x.getValue() + "\"")
            .collect(Collectors.joining(",", "{", "}"));
    return Response.ok(jsonStr).build();
}

The response return by this function would be following: {"A":"1","B":"2","C":"3"}

I found a "neat" reflection tweak on "the interwebs" that I like to share. (origin: https://towardsdatascience.com/create-an-ordered-jsonobject-in-java-fb9629247d76)

It is about to change underlying collection in org.json.JSONObject to an un-ordering one (LinkedHashMap) by reflection API.

I tested succesfully:

import java.lang.reflect.Field;
import java.util.LinkedHashMap;
import org.json.JSONObject;

private static void makeJSONObjLinear(JSONObject jsonObject) {
    try {
            Field changeMap = jsonObject.getClass().getDeclaredField("map");
            changeMap.setAccessible(true);
            changeMap.set(jsonObject, new LinkedHashMap<>());
            changeMap.setAccessible(false);
        } catch (IllegalAccessException | NoSuchFieldException e) {
            e.printStackTrace();
        }
}

[...]
JSONObject requestBody = new JSONObject();
makeJSONObjLinear(requestBody);

requestBody.put("username", login);
requestBody.put("password", password);
[...]
// returned   '{"username": "billy_778", "password": "********"}' == unordered
// instead of '{"password": "********", "username": "billy_778"}' == ordered (by key)

JavaScript objects, and JSON, have no way to set the order for the keys. You might get it right in Java (I don't know how Java objects work, really) but if it's going to a web client or another consumer of the JSON, there is no guarantee as to the order of keys.

You cannot and should not rely on the ordering of elements within a JSON object.

From the JSON specification at http://www.json.org/

An object is an unordered set of name/value pairs

As a consequence, JSON libraries are free to rearrange the order of the elements as they see fit. This is not a bug.

Just add the order with this tag

@JsonPropertyOrder({ "property1", "property2"})

As all are telling you, JSON does not maintain "sequence" but array does, maybe this could convince you: Ordered JSONObject

For Java code, Create a POJO class for your object instead of a JSONObject. and use JSONEncapsulator for your POJO class. that way order of elements depends on the order of getter setters in your POJO class. for eg. POJO class will be like

Class myObj{
String userID;
String amount;
String success;
// getter setters in any order that you want

and where you need to send your json object in response

JSONContentEncapsulator<myObj> JSONObject = new JSONEncapsulator<myObj>("myObject");
JSONObject.setObject(myObj);
return Response.status(Status.OK).entity(JSONObject).build();

The response of this line will be

{myObject : {//attributes order same as getter setter order.}}

Download "json simple 1.1 jar" from this https://code.google.com/p/json-simple/downloads/detail?name=json_simple-1.1.jar&can=2&q=

And add the jar file to your lib folder

using JSONValue you can convert LinkedHashMap to json string

u can retain the order, if u use JsonObject that belongs to com.google.gson :D

JsonObject responseObj = new JsonObject();
responseObj.addProperty("userid", "User 1");
responseObj.addProperty("amount", "24.23");
responseObj.addProperty("success", "NO");

Usage of this JsonObject doesn't even bother using Map<>

CHEERS!!!

Underscore-java uses linkedhashmap to store key/value for json. I am the maintainer of the project.

Map<String, Object> myObject = new LinkedHashMap<>();
myObject.put("userid", "User 1");
myObject.put("amount", "24.23");
myObject.put("success", "NO");

System.out.println(U.toJson(myObject));

Not sure if I am late to the party but I found this nice example that overrides the JSONObject constructor and makes sure that the JSON data are output in the same way as they are added. Behind the scenes JSONObject uses the MAP and MAP does not guarantee the order hence we need to override it to make sure we are receiving our JSON as per our order.

If you add this to your JSONObject then the resulting JSON would be in the same order as you have created it.

import java.io.IOException;
import java.lang.reflect.Field;
import java.util.LinkedHashMap;
import org.json.JSONObject;
import lombok.extern.java.Log;

@Log
public class JSONOrder {

    public static void main(String[] args) throws IOException {

        JSONObject jsontest = new JSONObject();
        try {
            Field changeMap = jsonEvent.getClass().getDeclaredField("map");
            changeMap.setAccessible(true);
            changeMap.set(jsonEvent, new LinkedHashMap<>());
            changeMap.setAccessible(false);
        } catch (IllegalAccessException | NoSuchFieldException e) {
            log.info(e.getMessage());
        }
        jsontest.put("one", "I should be first");
        jsonEvent.put("two", "I should be second");
        jsonEvent.put("third", "I should be third");
        System.out.println(jsonEvent);
    }
}

from lemiorhan example i can solve with just change some line of lemiorhan's code use:

JSONObject json = new JSONObject(obj);

instead of this:

JSONObject json = (JSONObject) obj

so in my test code is :

Map item_sub2 = new LinkedHashMap();
item_sub2.put("name", "flare");
item_sub2.put("val1", "val1");
item_sub2.put("val2", "val2");
item_sub2.put("size",102);

JSONArray itemarray2 = new JSONArray();
itemarray2.add(item_sub2);
itemarray2.add(item_sub2);//just for test
itemarray2.add(item_sub2);//just for test


Map item_sub1 = new LinkedHashMap();
item_sub1.put("name", "flare");
item_sub1.put("val1", "val1");
item_sub1.put("val2", "val2");
item_sub1.put("children",itemarray2);

JSONArray itemarray = new JSONArray();
itemarray.add(item_sub1);
itemarray.add(item_sub1);//just for test
itemarray.add(item_sub1);//just for test

Map item_root = new LinkedHashMap();
item_root.put("name", "flare");
item_root.put("children",itemarray);

JSONObject json = new JSONObject(item_root);

System.out.println(json.toJSONString());

I agree with the other answers. You cannot rely on the ordering of JSON elements.

However if we need to have an ordered JSON, one solution might be to prepare a LinkedHashMap object with elements and convert it to JSONObject.

@Test
def void testOrdered() {
    Map obj = new LinkedHashMap()
    obj.put("a", "foo1")
    obj.put("b", new Integer(100))
    obj.put("c", new Double(1000.21))
    obj.put("d", new Boolean(true))
    obj.put("e", "foo2")
    obj.put("f", "foo3")
    obj.put("g", "foo4")
    obj.put("h", "foo5")
    obj.put("x", null)

    JSONObject json = (JSONObject) obj
    logger.info("Ordered Json : %s", json.toString())

    String expectedJsonString = """{"a":"foo1","b":100,"c":1000.21,"d":true,"e":"foo2","f":"foo3","g":"foo4","h":"foo5"}"""
    assertEquals(expectedJsonString, json.toString())
    JSONAssert.assertEquals(JSONSerializer.toJSON(expectedJsonString), json)
}

Normally the order is not preserved as below.

@Test
def void testUnordered() {
    Map obj = new HashMap()
    obj.put("a", "foo1")
    obj.put("b", new Integer(100))
    obj.put("c", new Double(1000.21))
    obj.put("d", new Boolean(true))
    obj.put("e", "foo2")
    obj.put("f", "foo3")
    obj.put("g", "foo4")
    obj.put("h", "foo5")
    obj.put("x", null)

    JSONObject json = (JSONObject) obj
    logger.info("Unordered Json : %s", json.toString(3, 3))

    String unexpectedJsonString = """{"a":"foo1","b":100,"c":1000.21,"d":true,"e":"foo2","f":"foo3","g":"foo4","h":"foo5"}"""

    // string representation of json objects are different
    assertFalse(unexpectedJsonString.equals(json.toString()))
    // json objects are equal
    JSONAssert.assertEquals(JSONSerializer.toJSON(unexpectedJsonString), json)
}

You may check my post too: http://www.flyingtomoon.com/2011/04/preserving-order-in-json.html