How to convert ArrayList to JSONArray() in Kotlin

Question

I have a list in my POJO class:

"userQuoteTravellers": [ 
     {
        "id": 1354,
        "quoteId": 526,
        "travellerId": null
     }
]

I want to pass this list as it is in JSONArray and passing it as:

JSONArray.put(list)

It is being sent as:

"userQuoteTravellers": [ "[]" ]

But I want to send it as

"userQuoteTravellers": []

How can I achieve this in Kotlin without using any loop?

have a look https://discuss.kotlinlang.org/t/send-json-post-req-with-json-array-and-multiple-json-object-in-volley/11034 — Abhinav Suman, Jan 28 '20 at 05:30
Does this answer your question? [convert ArrayList to JSONArray](https://stackoverflow.com/questions/4841952/convert-arraylistmycustomclass-to-jsonarray) — Md. Asaduzzaman, Jan 28 '20 at 05:52

Kalpesh Rupani · Answer 1 · 2020-01-28T05:41:48.693

6

With Dependencies

Add to your gradle:

implementation 'com.squareup.retrofit2:converter-gson:2.3.0'

Convert ArrayList to JsonArray

val jsonElements = (JsonArray) new Gson().toJsonTree(itemsArrayList)

Without Dependencies

val jsonElements = JSONArray(itemsArrayList)

edited Jan 28 '20 at 05:41

answered Jan 28 '20 at 05:29

Kalpesh Rupani

991
4
12

Is this using the same JSON library as the original question is asking about? – Simson Jan 28 '20 at 05:32
Yes, But If you don't want to use library than default is val jsArray = JSONArray(mylist). Just pass your generic array list to JSONArray arguments – Kalpesh Rupani Jan 28 '20 at 05:36
Here JSONArray is come from Collection only. No need to add library for that – Kalpesh Rupani Jan 28 '20 at 05:38
@KalpeshRupani No, it will not solve my problem because I have already tried in the same way. Read the question again. – Kartika Vij Jan 28 '20 at 06:28

Willi Mentzel · Accepted Answer · 2020-01-29T09:28:06.443

put adds the list as an element to the JSONArray. Thats not what you want. You want your JSONArray to represent the list.

JSONArray offers a constructor for that:

val jsonArray = JSONArray(listOf(1, 2, 3))

But there is a much easier way. You don't need to worry about single properties. Just pass the whole POJO.

Let's say you have this:

class QuoteData(val id: Int, val quoteId: Int, travellerId: Int?)
class TravelerData(val userQuoteTravellers: List<QuoteData>)

val travelerData = TravelerData(listOf(QuoteData(1354, 546, null)))

You just have to pass travelerData to the JSONArray constructor:

val travelerDataJson = JSONArray(travelerData)

and it will be represented like this:

"userQuoteTravellers": [ { "id": 1354, "quoteId": 526, "travellerId": null } ]

score 3 · Answer 3 · answered Jan 28 '20 at 07:08

If I read the JSONArray constructors correctly, you can build them from any Collection (arrayList is a subclass of Collection) like so:

val list = ArrayList<String?>()
list.add("jigar")
list.add("patel")
val jsArray = JSONArray(list)

You can also use GSON for read json see below example:

import com.google.gson.annotations.Expose
import com.google.gson.annotations.SerializedName
class userQuoteTravellers {
    @SerializedName("id")
    @Expose
    var id: Int? = null
    @SerializedName("quoteId")
    @Expose
    var quoteId: Int? = null
    @SerializedName("travellerId")
    @Expose
    var travellerId: Any? = null
}

score 1 · Answer 4 · edited Jan 29 '20 at 08:42

1

try this: val userQuote = response.getJSONArray("userQuoteTravellers")

then call the data inside like this:

for (i in 0 until userQuote.length()) {
    val quotes = userQuote.getJSONObject(i)
    // then call the other data here
}

edited Jan 29 '20 at 08:42

Simson

3,373
2
24
38

answered Jan 28 '20 at 06:34

score 1 · Answer 5 · answered Jan 28 '20 at 07:40

1

You can achieve this by using this

  implementation 'com.squareup.retrofit2:converter-gson:2.3.0'


  var gson = Gson()
  var jsonData = gson.toJson(PostPojo::class.java)

answered Jan 28 '20 at 07:40

Rajat Kumar Tyagi

116
5

How to convert ArrayList to JSONArray() in Kotlin

5 Answers5