android - 如何在 Kotlin Android 中从 JSON 中获取数据

Question

我想获取一些json数据，见图中绿色箭头:

问题是 Android Studio 不允许我获取我想要的数据。它停止直到前一步(我认为)。在我的适配器类检查中:

holder?.view?.textWeather?.text = weatherFor.weather.toString()

还在模拟器中显示红色箭头，这是什么？

下面是我的主要 Activity 的 json 方法，其中包含我要为其获取数据的类，以及关联的 Adapter 类。

主要 Activity

fun fetchJson() {
     val url="https://api.openweathermap.org/data/2.5/forecast?q=Prague,CZ&appid=4cf7f6610d941a1ca7583f50e7e41ba3"
     val request=Request.Builder().url(url).build()
     val client= OkHttpClient()
     client.newCall(request).enqueue(object :Callback {

         override fun onResponse(call: Call?, response: Response?) {
             val body=response?.body()?.string()
             println(body)

             val gson=GsonBuilder().create()

             val forecastfeed=gson.fromJson(body,ForecastFeed::class.java)

             runOnUiThread{
                 recyclerView_main.adapter=MainAdapter(forecastfeed)
             }
         }

         override fun onFailure(call: Call?, e: IOException?) {
             println("Failed to execute request")
         }
     })
}

class ForecastFeed(val list:List<ForecastWeatherList>) { }

class ForecastWeatherList(val weather:List<WeatherData>) { }

class WeatherData(val main:String,val icon:String) { }

适配器

class MainAdapter(val forecastfeed: ForecastFeed): RecyclerView.Adapter<CustomViewHolder>() {

    val forecastWeather = listOf<String>("First","Second")

    override fun onBindViewHolder(holder: CustomViewHolder, position: Int) {
        val weatherFor = forecastfeed.list.get(position)
        holder?.view?.textWeather?.text = weatherFor.weather.toString()
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomViewHolder{
        //how do we even create a view
        val layoutInflater =LayoutInflater.from(parent?.context)
        val cellForRow=layoutInflater.inflate(R.layout.weather_row,parent,false)
        return CustomViewHolder(cellForRow)
    }    

    override fun getItemCount(): Int {
        return forecastfeed.list.count()
    }
}

class CustomViewHolder(val view: View):RecyclerView.ViewHolder(view) { }

Answer 1

您可以手动格式化数据

holder?.view?.textWeather?.text = "weather ${weatherFor.weather.map{it.main}.joinToString(", ")}"

或使用 data classes