Kotlin JSON's array is not a primitive array

Question

Good morning,

I'm currently coding on android (kotlin), and I'm trying to parse a json file with the url.

Everything is working fine when it comes with the request, but since the json is a little bit tricky, I can't seem to find a way to get my informations properly.

Every time I get a JSON exeption error or an error telling me that the array is not a primitive one.

This is the essential part of my code were the magic happens.

try {
            // Create JSONObject from string response if your response start from Array [ then create JSONArray
            val rootJsonObject = JSONObject(results)
            val isSucess = rootJsonObject.optString("code")

            if (isSucess == "200") {

                val streetArray = rootJsonObject.getJSONObject("data").getJSONObject("nearstations")
                val mJsonArray = JSONArray(streetArray)

                for (i in 0 until mJsonArray.length()) {

                    val sObject = mJsonArray.getJSONObject(i).toString()
                    val mItemObject = JSONObject(sObject)

                    val id = mItemObject.getString("id")
                    val street_name = mItemObject.getString("street_name")


                    val mHash = HashMap<String, String>()

                    mHash["id"] = "Id: $id"
                    mHash["street_name"] = "Name: $street_name"

                    streetList.add(mHash)
                }

                // This is simple Adapter (android widget) for ListView
                val simpleAdapter = SimpleAdapter(
                    applicationContext, streetList,
                    R.layout.simple_listview_item,
                    // Add String[] name same as HashMap Key
                    arrayOf("id", "street_name"),
                    intArrayOf(R.id.tv_id, R.id.tv_street_name))

                Lv_client.adapter = simpleAdapter

                Lv_client.setOnItemClickListener { parent, view, position, id ->
                    Toast.makeText(applicationContext, "Selected item is " + position, Toast.LENGTH_SHORT).show()
                }

            }

This is a small part of the JSON from the following (http://barcelonaapi.marcpous.com/bus/nearstation/latlon/%2041.3985182/2.1917991/1.json)

"code": 200,
  "data": {
    "nearstations": [
      {
        "id": "1",
        "street_name": "Almogàvers-Àvila",
        "city": "BARCELONA",
        "utm_x": "432542,5460",
        "utm_y": "4583524,2340",
        "lat": "41.3985182",
        "lon": "2.1917991",
        "furniture": "Pal",
        "buses": "06 - 40 - 42 - 141 - B25 - N11",
        "distance": "0"
      },
      {
        "id": "2721",
        "street_name": "Àvila-Almogàvers",
        "city": "BARCELONA",
        "utm_x": "432641,0420",
        "utm_y": "4583509,2710",
        "lat": "41.3985182",
        "lon": "2.1917991",
        "furniture": "Pal",
        "buses": "92",
        "distance": "0"
      },

Chris · Accepted Answer · 2020-03-01 14:24:42Z

3

First thing is you never actually asked a question. You said that there was a problem but never specified where. One thing I noticed is that you're checking the value of isSucess as a String, the json link shows the code is returned as a numerical value. - Use optInt instead of optString and then remove the double quotes around the if condition may help you along.

if (isSucess == 200) {

However, I think you could simplify your task greatly by using a library which deals with the parsing of the json response automatically and then return a model of the response in the form of data objects.

One such library is gson. You'd use it as follows..

val rootJsonObject = Gson().fromJson(json, RootJsonObject::class.java)

To begin with you'd need to declare your data model classes :

data class RootJsonObject(
    val code: Int,
    val data: DataJsonObject
)

data class DataJsonObject(
    val nearstations: List<NearStation>
)

data class NearStation(
    val id: String,
    val street_name: String,
    val city: String,
    val utm_x: String,
    val utm_y: String,
    val lat: String,
    val lon: String,
    val furniture: String,
    val buses: String,
    val distance: String
)

Then you'd parse the json like this :

val rootJsonObject = Gson().fromJson(json, RootJsonObject::class.java)
if (rootJsonObject.code != 200) {
    return
}

And you would use the rootJsonObject.data.nearstations variable as the adapters list.

Hope this helps.

answered Mar 1, 2020 at 14:24

Chris

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4 Comments

Tim Soph Over a year ago

Thank you very much, I'm gonna look into it immediately :)

Tim Soph Over a year ago

HEY! It finally worked! Thank you! So hum, how can I post the modifications I made for other people?

Chris Over a year ago

awesome. you could just post a response to your question stating what you did to resolve the problem. Good Work!

Tim Soph Over a year ago

Okay Thanks again!

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