java.lang.ClassCastException：在 Kotlin 中无法将 CustomAdapter 强制转换为 android.widget.ArrayAdapter

Question

当我尝试在 Kotlin 中创建自定义适配器类时遇到上述错误

源代码

MainActivity.kt

 var adapterC:CustomAdapter = CustomAdapter(this,Statearray)
 spinnerState.adapter=adapterC

CustomAdapter.kt

class CustomAdapter(val activity: Activity,val array:JSONArray) : BaseAdapter(), ListAdapter
{
    lateinit var ItemName: TextView

    override fun getView(position: Int, convertView: View?, parent: ViewGroup?): View? {
    var view=convertView
    if (view == null)
        view = activity.layoutInflater.inflate(R.layout.spinnerlayout, null)
    try {

        ItemName = view?.findViewById(R.id.ItemName) as TextView
        val obj = array.getJSONObject(position)
        ItemName.setText(obj.getString("Name"))
        view.setTag(obj.getString("Id"))

    } catch ( e:JSONException) {
        Log.e("At Custom Class",e.toString())
    }

    return view
}

override fun getItem(position: Int): JSONObject {
    return array.optJSONObject(position)
}

override fun getItemId(position: Int): Long {
    var jsonObject=getItem(position)
    return jsonObject.optLong("id")
}

override fun getCount(): Int {
    return array.length()
}

}

需要帮助我不知道我做错了什么。

Answer 1

我终于弄明白了.. 问题是，我使用了一个只支持 ArrayAdapter 的微调库

我使用的库是

com.toptoche.searchablespinner:searchablespinnerlibrary:1.3.1

只支持arrayadapter

Answer 2

ClassCastException

抛出以指示代码已尝试将对象强制转换为 它不是实例的子类。

仅供参考

您添加了 Multiple Adapter。删除第二个。

不要

class CustomAdapter(val activity: Activity,val array:JSONArray) : BaseAdapter(), ListAdapter

做

class CustomAdapter(context: Context,var arrayLIST: ArrayList<Response>) : BaseAdapter() {

演示

var arrayLIST: ArrayList<Response>? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        arrayLIST=ArrayList()
        val jsonObj = ("[{\"Id\":\"35\",\"Name\":\"Kerala\"},{\"Id\":\"36\",\"Name\":\"Tamilnadu\"}]")
        val jo = JSONArray(jsonObj)
        val num = 0 until jo.length()
        for (i in num) {
            val loanObj = jo.getJSONObject(i)
            val Id      = loanObj.getString("Id")
            val Name    = loanObj.getString("Name")

            arrayLIST!!.add(Response(Id,Name))


        }
      var adapterC:CustomAdapter = CustomAdapter(this@MainActivity,arrayLIST)

Response.kt

data class Response
(
        @SerializedName("id")               val id               : String,
        @SerializedName("name")            val  name             : String
)

注意

确保添加，

   implementation "com.google.code.gson:gson:2.3.0"
    implementation "com.squareup.retrofit2:converter-gson:2.3.0"