get array from inside many objects in kotlin - kotlin

Question

l am try to build simple app provide flight schedule . the problem is l have many object in json url and the array list inside of these object and l cant to get array list from objects because l got error fatal Caused by: org.json.JSONException: Value
my data json api
{
"result": {
"response": {
"airport": {
"pluginData": {
"schedule": {
"arrivals": {
"data": [
{
"flight": {
"identification": {
"id": null,
"row": 4832637003,
"number": {
"default": "ZP4801",
"alternative": null
},
"callsign": null,
"codeshare": null
}
}
}
]
}
}
}
}
}
}
}
my code for getting data json of array list
private fun handleJson (jsonString: String?){
val jsonArray = JSONArray(jsonString)
val list = ArrayList<FlightShdu>()
var x = 0
while (x < jsonArray.length()){
val jsonObject = jsonArray.getJSONObject(x)
list.add(FlightShdu(
jsonObject.getInt("id"),
jsonObject.getString("callsign")
))
x++
}
val adapter = ListAdapte(this#MainActivity,list)
flightShdu_list.adapter = adapter
}

Answer 1

I would normally suggest for a full structure of the JSON via data classes, as this methodology could potentially be expensive to run multiple times over and over... The following highlights a method to dig into the JSON through jsonObjects by name, and then take the final layer of "identification" and populates a data class that is serializable with the resulting object
import kotlinx.serialization.Serializable
import kotlinx.serialization.json.Json
import kotlinx.serialization.json.JsonConfiguration
import kotlinx.serialization.json.JsonDecodingException
import kotlinx.serialization.json.JsonElement
val data =
"""
{
"result": {
"response": {
"airport": {
"pluginData": {
"schedule": {
"arrivals": {
"data": [{
"flight": {
"identification": {
"id": null,
"row": 4832637003,
"number": {
"default": "ZP4801",
"alternative": null
},
"callsign": null,
"codeshare": null
}
}
}]
}
}
}
}
}
}
}
"""
#Serializable
data class FlightIdentification(
val id: Int?,
val row: String,
val number: IdentificationNumber,
val callsign: String?,
val codeshare: String?
) {
#Serializable
data class IdentificationNumber(
val default: String,
val alternative: String?
)
}
val json = Json(JsonConfiguration.Stable)
fun JsonElement?.get(name: String): JsonElement? {
return if (this == null) null
else this.jsonObject[name]
}
fun handleJson(jsonString: String) {
val obj = json.parseJson(jsonString)
val data = obj.get("result").get("response").get("airport").get("pluginData")
.get("schedule").get("arrivals").get("data")
if (data != null) {
val flight = data.jsonArray[0]
.get("flight").get("identification")
try {
val res = json.parse(FlightIdentification.serializer(), flight.toString())
println(res)
} catch (e: JsonDecodingException) {
println("Decode: ${e.message}")
}
}
}
handleJson(data)