kotlin - 在文本编辑中设置文本 '' 未找到结果 ''

Question

在修改我的代码时需要您的帮助，我正在尝试通过通过 data json 搜索航类号来构建一个包含航类时刻表的应用程序。我正在使用编辑文本和 AsyncTask 以及自定义列表适配器 ListView 。我的应用程序工作正常，但问题是当用户以错误的方式输入航类号时，我得到了 FATAL EXCEPTION .因为数据 json url 当用户输入正确的航类号时他有数据数组，其他方式如果用户输入错误的航类号数据 json url 他将返回数据 json 在 jsonobject我得到 FATAL EXCEPTION是

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.iraqairoirt.iraqairports, PID: 5380
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)
 Caused by: java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386) 
 Caused by: org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONArray
    at org.json.JSON.typeMismatch(JSON.java:111)
    at org.json.JSONArray.<init>(JSONArray.java:96)
    at org.json.JSONArray.<init>(JSONArray.java:108)
    at com.iraqairoirt.iraqairports.BaghdadAirport.FlightSearch$Arr.handleJson(FlightSearch.kt:106)
    at com.iraqairoirt.iraqairports.BaghdadAirport.FlightSearch$Arr.onPostExecute(FlightSearch.kt:90)
    at com.iraqairoirt.iraqairports.BaghdadAirport.FlightSearch$Arr.onPostExecute(FlightSearch.kt:58)
    at android.os.AsyncTask.finish(AsyncTask.java:660)
    at android.os.AsyncTask.-wrap1(AsyncTask.java)
    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:677)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6776)
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386) 

数据 json 如果输入正确 l 获取数据数组

{
  "result": {
    "request": {},
    "response": {
      "data": [
        {
          "identification": {
            "id": null,
            "row": 4849651452,
            "callsign": null,
            "codeshare": null
          },
          "status": {
            "live": false,
            "text": "Scheduled",
            "icon": null,
            "estimated": null,
            "ambiguous": false
          }
        }
      ]
    }
  }
}

如果输入错误 l 获取数据 json 对象和致命异常

{
  "result": {
    "request": {},
    "response": {
      "data": null
    }
  }
}

类事件，包括列表适配器

class FlightSearch : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_flight_search)
        flightlistlaout.bringToFront()

    }

    fun getflightsearchresult(view:View){

        val FlightNumber=flightnumbertext.text.toString()
//        val auto=autoCompleteTextView.text.toString()

        if(FlightNumber.trim().length>0) {
            val url = "flight/list.json?query="+FlightNumber+"&fetchBy=flight&page=1&limit=100&token="
            Arr().execute(url)

            Toast.makeText(applicationContext, "Message : ", Toast.LENGTH_SHORT).show()
        }else{
            Toast.makeText(applicationContext, "Please enter some message! ", Toast.LENGTH_SHORT).show()
        }
    }
    inner class Arr : AsyncTask<String, String, String>() {


        override fun onPreExecute() {
            super.onPreExecute()


        }

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

            var text: String
            val connection = URL(url[0]).openConnection() as HttpURLConnection
            connection.connectTimeout = 700

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


            } finally {

                connection.disconnect()

            }
            return text
        }

        override fun onPostExecute(result: String?) {

            super.onPostExecute(result)
            handleJson(result)


        }

        override fun onProgressUpdate(vararg text: String?) {


        }

        @SuppressLint("WrongViewCast")
        private fun handleJson(jsonString: String?) {

            val jsonObj = JSONObject(jsonString)
            val result = jsonObj.getJSONObject("result")
            val response = result.getJSONObject("response")
            val jsonArray = JSONArray(response.get("data").toString())


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

                            val jsonObject = jsonArray.getJSONObject(x)


                            list.add(
                                FlightShdu(
                                    jsonObject.getJSONObject("identification").getJSONObject("number").getString("default"),
                                    jsonObject.getJSONObject("airline").getString("name"),
                                    jsonObject.getJSONObject("status").getJSONObject("generic").getJSONObject("status").getString(
                                        "text"
                                    ),
                                    jsonObject.getJSONObject("airline").getJSONObject("code").getString("icao"),
                                    jsonObject.getJSONObject("time").getJSONObject("scheduled").getString("arrival"),
                                    jsonObject.getJSONObject("airport").getJSONObject("origin").getJSONObject("code").getString(
                                        "iata"


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

                        var adapter = FlightSearchAdpater(this@FlightSearch, list)
                        flightsearchlists.adapter = adapter
        }





        }


    }
    class FlightSearchAdpater (val context: Context, val list: ArrayList<FlightShdu>): BaseAdapter() {


        @SuppressLint("ViewHolder", "NewApi", "WrongViewCast")
        override fun getView(p0: Int, convertView: View?, parent: ViewGroup?): View {

            val view : View = LayoutInflater.from(context).inflate(R.layout.baghdad_arrivel_list,parent,false)

            val list = list[p0]
            val LogoAriline = view.findViewById(R.id.logo_image) as ImageView
            val status = view.findViewById(R.id.ali_id) as AppCompatTextView
            val Airport = view.findViewById(R.id.airportid) as AppCompatTextView
            val code = view.findViewById(R.id.code_id) as AppCompatTextView
            val TimeFlight = view.findViewById(R.id.time_id) as AppCompatTextView
            val checkiflive = view.checkifliveTextId
            view.callsign_id.text=list.Callsign
            view.airline_id.text=list.Airline
            code.text = list.code
            view.ali_id.text=list.Stauts
            status.text= list.Stauts
            TimeFlight.text = getDateTime(list.TimeFlight)

            Picasso.with(context).load(Uri.parse("/data/operators/"+status.text.toString()+"_logo0.png"))
                .error(R.drawable.logo).into(LogoAriline)

            Airport.text= list.Airport
            view.model_id.text=list.Model
            checkiflive.text=list.IfLive




        private fun getDateTime(s: String): String? {
            try {
                val sdf = SimpleDateFormat("EE, MMM d KK:mm a")
                val netDate = Date(s.toLong() * 1000)
                return sdf.format(netDate)
            } catch (e: Exception) {
                return e.toString()

            }
        }

        override fun getItem(p0: Int): Any {
            return list [p0]
        }

        override fun getItemId(p0: Int): Long {
            return p0.toLong()
        }

        override fun getCount(): Int {
            return list.size
        }



    }

当我跟踪 FATAL EXCEPTION: main使用此代码在第 106 行找到了主要问题 val jsonArray = JSONArray(response.get("data").toString())
请我想用代码人回答，我想在用户输入错误信息时添加文本，他得到响应示例“未找到航类，请确保航类号”

谢谢你

Answer 1

Caused by: org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONArray

你应该检查 getJSONArray 是否为空

如果您的 Json "data":[]，下面的代码将起作用

  val jsonData  = response.getJSONArray("data")
    if(jsonData.length()!=0)
    {
        // Do your work        
    }

仅供引用

您应该检查您的 Json 数据 JSONArray 或 String .

 Object dataVal= response.get("data");
     if (dataValis is JSONArray)
        {
              // Your code                 
        }
     else
      { 
           // null value
      }