如何在kotlin中添加加载对话框

当我的应用程序加载数据json url时，我试图添加加载对话框，因为在午餐应用程序出现数据之前，屏幕显示为空白

这是密码

inner class Dep : AsyncTask<String, String, String>(){


        //        for build connection
        override fun doInBackground(vararg url: String?): String{

            var text : String
            val connection = URL(url[0]).openConnection() as HttpURLConnection

            try {
                connection.connect()
                text = connection.inputStream.use { it.reader().use{reader -> reader.readText()} }


            } finally{

                connection.disconnect()

            }
            return text
        }

        override fun onPostExecute(result: String?) {

            val progressDialog = ProgressDialog(Context,this@MainActivity)
            progressDialog.setMessage("loading")
            progressDialog.setCancelable(false)
            progressDialog.show()

            super.onPostExecute(result)
            handleJson(result)

            if (progressDialog != null)
                progressDialog.dismiss();

        }

        private fun handleJson (jsonString: String?){

            val jsonObj = JSONObject(jsonString)
            val result = jsonObj.getJSONObject("result")
            val response = result.getJSONObject("response")
            val airport = response.getJSONObject("airport")
            val pluginData = airport.getJSONObject("pluginData")
            val schedule = pluginData.getJSONObject("schedule")
            val arrivals = schedule.getJSONObject("departures")
//        val data = arrivals.getJSONObject("data")
            val jsonArray = JSONArray(arrivals.get("data").toString())

            val list =  ArrayList<FlightShdu>()
            var x = 0
            while (x < jsonArray.length()){

                val jsonObject = jsonArray.getJSONObject(x)



                list.add(FlightShdu(

                    jsonObject.getJSONObject("flight").getJSONObject("identification").getJSONObject("number").getString("default"),
                    jsonObject.getJSONObject("flight").getJSONObject("airline").getString("name"),
                    jsonObject.getJSONObject("flight").getJSONObject("status").getString("text"),
                    jsonObject.getJSONObject("flight").getJSONObject("airline").getJSONObject("code").getString("icao"),
                    jsonObject.getJSONObject("flight").getJSONObject("time").getJSONObject("scheduled").getString("departure")


                    ))


                x++
            }
            list.forEach(::println)

            val adapter = ListAdapte(this@MainActivity,list)
            flight_dep_list.adapter = adapter

        }

        //    for get items from json api
        override fun onProgressUpdate(vararg values: String?) {

        }


    }

我犯了红线错误

分类器“上下文”没有伴生对象，因此必须在此处初始化

---

我需要添加进度对话框xml吗

您需要像下面这样创建上下文实例：lateinit var context2:Context，然后是context2=container！！。在activity或Fragment方法中添加上下文，只需通过ProgressDialog传递context2

就可以在内部类下声明ProgressDialog。然后在onBeforeExecute（）下显示对话框并显示它。将其隐藏在onPostExecuteFunction下（在OnPostExecute中显示对话框太迟）progressdialog已被弃用，请改用progressbar您能给我举个例子吗

 override fun onPostExecute(result: String?) {

        val progressDialog = ProgressDialog(Context,this@MainActivity)
        progressDialog.setMessage("loading")
        progressDialog.setCancelable(false)
        progressDialog.show()

        super.onPostExecute(result)
        handleJson(result)

        if (progressDialog != null)
            progressDialog.dismiss();

    }