Convert String to JsonObject in kotlin returns null

Question

Edit Found Solution:

Found the error in my code. I'm running this on a unit test and Android doesn't use JSON objects on unit tests because it's part of android. That's why it was returning null.

Question:

I'm tying to convert my String back to a JsonObject using JSONObject("string")

Here is a sample of my String:

{
  "sessions": [
    {
      "locations": [
        {
          "lat": "14.2294625",
          "lng": "121.1509005",
          "time": 1560262643000,
          "speed": 0,
          "speedLimit": 0
        },
        {
          "lat": "14.2294576",
          "lng": "121.1509498",
          "time": 1560262713000,
          "speed": 0,
          "speedLimit": 0
        },
        {
          "lat": "14.2294576",
          "lng": "121.1509498",
          "time": 1560262714000,
          "speed": 0,
          "speedLimit": 0
        }
      ],
      "name": "1.5645220491E12"
    }
  ]
}

Its returning null on my JsonObjects:

content = "the string above"

var obj = JSONObject(content.substring(content.indexOf("{"), content.lastIndexOf("}") + 1))
System.out.println("obj1: " + obj.toString())

obj = JSONObject(content)
System.out.println("obj1: " + obj.toString())

var obj1 = JSONArray(content)
System.out.println("obj1: " + obj1.toString())

obj1 = JSONArray(content.substring(content.indexOf("{"), content.lastIndexOf("}") + 1))
System.out.println("obj2: " + obj1.toString())

All the outputs of this are null. Any way to know what error happens so I can adjust my json string?

maybe it's better to create a pojo model and use Gson library? Or you don't have such opportunity? — Sergei Mikhailovskii
– Sergei Mikhailovskii, Commented Jul 31, 2019 at 8:05
@SergeiMikhailovskii this is just a simple unit test reading from a local json text file. Yes that is possible but I want to know why this code is not working. — Marlon
– Marlon, Commented Jul 31, 2019 at 8:13

Evgeny Ezhov · Accepted Answer · 2020-12-16 13:03:45Z

3

Since you are running your code with Junit, it running on the SDK on your computer. This SDK doesn't provide everything, some are just some skeleton class providing signature of method and documentation but not the code. So you can't execute directly.

Try to add the library in testing

testImplementation 'org.json:json:your_version'

See the version here :

http://mvnrepository.com/artifact/org.json/json

This is based on the answer on this post: JSONObject returns a non null value of "null" after instantiating with string

answered Dec 16, 2020 at 13:03

Evgeny Ezhov

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Marat Zangiev · Accepted Answer · 2019-07-31 08:14:13Z

2

There is no need to substring your JSON string. Put it inside JSONObject and it will work fine.
If you need to get neasted objects use getJSONObject or getJSONArray methods
Show your content string in code (or how do you load it)

Your edited code

val content = "the string above"

var obj = JSONObject(content)

answered Jul 31, 2019 at 8:14

Marat Zangiev

1,4729 silver badges16 bronze badges

3 Comments

Marlon Over a year ago

Already did that, you can see in my code I have tried many different ways to convert it to an object, all of them return null.

Marat Zangiev Over a year ago

Show how you load your string

Supun Ayeshmantha Over a year ago

I tried this on a volley StringResponse and worked fine

Trung Nguyen · Accepted Answer · 2019-07-31 09:01:45Z

I run this funtion to parse your string and it's ok. Your string is valid. Can you specify how do you init val content

 fun parseJson() {
    var stringJson = "{\"sessions\": [{\"locations\": [{\"lat\": \"14.2294625\",\"lng\": \"121.1509005\",\"time\": 1560262643000,\"speed\": 0,\"speedLimit\": 0},{\"lat\": \"14.2294576\",\"lng\": \"121.1509498\",\"time\": 1560262713000,\"speed\": 0,\"speedLimit\": 0},{\"lat\": \"14.2294576\",\"lng\": \"121.1509498\",\"time\": 1560262714000,\"speed\": 0,\"speedLimit\": 0}],\"name\": \"1.5645220491E12\"}  ]}"

    var obj = JSONObject(stringJson)
    System.out.println("obj1: $obj")
    var sessionArray: JSONArray = obj.optJSONArray("sessions")
    System.out.println("obj1: $sessionArray")
    var firstObject = sessionArray[0]
    System.out.println("obj1: $firstObject")
}

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