check if JSON is a JSONObject or JSONArray in kotlin

Question

I am getting JSON string from my server. I have data which looks like this (JSON Array)

{
  "result": {
    "response": {
      "data": [
        {
          "identification": {
            "id": null,
            "number": {
              "default": "IA224",
              "alternative": null
            },
            "callsign": null,
            "codeshare": null
          }
        }
      ]
    }
  }
}

but some times this data can be (JSON object) or be null if l entered wrong information

data :  null

I want to do different operations when its object and different when its an array. I am getting following exception

Caused by: org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONArray

l did this code but he dose not work

val jsonArray = JSONArray(response.get("data").toString())

            if(jsonArray.isNull(0)){
               jsonArray.getJSONObject(0).getString("data");
            }

silwar · Accepted Answer · 2018-12-07 07:01:09Z

6

You can check using is operator to check if object is JsonObject or JsonArray as below

            val jsonObj = JSONObject(jsonString)

            if(jsonObj is JsonArray){
                  //handle operation with JsonArray
            }else if (jsonObj is JsonObject){
                  // treat this as JsonObject
            }

You can also use when expression in kotlin for checking these conditions like

            when(jsonObj){
                is JsonObject -> { // treat this as JsonObject}
                is JsonArray -> { //treat this as JsonArray}
                else -> { //I have to find some other way to handle this}
            }

Update - For your Json,parsing should be done like this

Create pojo for following json say Xyz.kt

 {
  "identification": {
    "id": null,
    "number": {
      "default": "IA224",
      "alternative": null
    },
    "callsign": null,
    "codeshare": null
  }
}

    val resultJson = JSONObject(jsonString)
    val responseJson = resultJson.getJsonObject("response")
    val dataList = responseJson.getJsonArray("data")

If everytime you are getting same structure for Json response then you dont have to check if dataList is JsonArray or JsonObject. You can simply iterate through dataList to get list of Xyz objects or get first JsonElement(object of Xyz) using get() method.

edited Dec 7, 2018 at 7:01

answered Dec 7, 2018 at 6:40

silwar

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4 Comments

Ali Ghassan Over a year ago

thank you for answered , your code is working fine , but there is problem with jsonarray . when l run app l got the response of all json data . !

silwar Over a year ago

check updated answer. I hope this will solve your issue

Ali Ghassan Over a year ago

actully its same l got structure for Json response . if l delete expression when or if and try to enter value in edit text and execute l got exception because l entered wrong information and the exception is Caused by: org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONArray l dont know what l have to do

silwar Over a year ago

you can also use Gson or Jackson converter which will directly return object with parsed response

Rohit Jagtap · Accepted Answer · 2019-08-02 12:24:10Z

3

Use the below code to identify whether the JSON string is a JSONObject or JSONArray,

var json = JSONTokener(yourJSONString).nextValue()
when (json) {
    is JSONObject -> { //it is a JsonObject
    }
    is JSONArray -> { //it is a JsonArray
    }
    else -> { //handle the odd scenario
    }
}

edited Aug 2, 2019 at 12:24

answered Aug 2, 2019 at 11:58

Rohit Jagtap

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Comments

Anshul Nema · Accepted Answer · 2025-04-21 05:38:56Z

0

Create a function like this. Pass a string in a parameter and return a value.

fun isJSONValid(test: String?): Boolean {
    try {
        JSONObject(test)
    } catch (ex: JSONException) {
        // edited, to include @Arthur's comment
        // e.g. in case JSONArray is valid as well...
        try {
            JSONArray(test)
        } catch (ex1: JSONException) {
            return false
        }
    }
    return true
}

answered Apr 21 at 5:38

Anshul Nema

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