andoid studio kotlin - java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

Question

i am new to kotlin and i'm trying to call an api that has a array form ["value1","value2"] to display in my main activity textView and i keep getting this error java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $ can someone help i'm using kotlin

this is the Data Class:

data class ApiValuesItem(

    val values:Array<String?>

)

this is my interface:

import retrofit2.Call
import retrofit2.http.GET

interface ApiInterface {

    @GET("values")
    fun getApiValue(): Call<ApiValuesItem?>

}

and this is what i wrote in the mainActivity:

class MainActivity : AppCompatActivity() {

    companion object {
        
       const val BASE_URL = "http://xx.xx.xx.xx/sfa/api/"
    }
    
    
    @SuppressLint("ResourceType")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

get_Api.setOnClickListener {
getApiValues()
}
}

private fun getApiValues() {
val retrofitBuilder = Retrofit.Builder()
.addConverterFactory(GsonConverterFactory.create())
.baseUrl(BASE_URL)
.build()
.create(ApiInterface::class.java)

        val retrofitData = retrofitBuilder.getApiValue()
    
        retrofitData.enqueue(object : Callback<ApiValuesItem?> {
            override fun onResponse(
                call: Call<ApiValuesItem?>,
                response: Response<ApiValuesItem?>
            ) {
                val responseBody = response.body()!!
    
               val myStringBuilder = StringBuilder()
                for (ApiValues in responseBody){
                   myStringBuilder.append(ApiValues.values)
                   myStringBuilder.append(", ")
               }
                Api_Res.text = myStringBuilder
    
               }
    
            override fun onFailure(call: Call<ApiValuesItem?>, t: Throwable) {
                Log.d("MainActivity","onFailure: "+t.message)
                Api_Res.text = t.message
            }
        })
    }
    
    }

Answer 1

Your Json:

["value1","value2"]

This is actually json array of strings.

If you define like below, it will be expecting json object. In that object , it will be expecting String Array with key "values"

data class ApiValuesItem(
    val values:Array<String?>
)

You model class will be mapped like this.

{"values":["value1","value2"]}

But your root is directly an array.

So instead of Callback<ApiValuesItem?> you should make it as any Iterable<String>. You can use arraylist like below.

Callback<ArrayList<String>?>
Call<ArrayList<String>?>
Response<ArrayList<String>?>