How to fetch data from JSON in Kotlin Android

Question

I want to fetch some json data, see in the image the green arrow:

The problem is that Android Studio doesn't let me get the data I want. It stops until a step before (I think). In my adapter class check:

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

Also it shows me in the emulator the red arrow, what is this?

Below is my main Activity's json method with the classes i want to fetch data for, and the associated Adapter class.

Main 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) { }

Adapter

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) { }

Akaki Kapanadze · Accepted Answer · 2018-08-20 14:53:59Z

2

You can format the data manually

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

or use data classes

edited Aug 20, 2018 at 14:53

answered Aug 20, 2018 at 12:16

Akaki Kapanadze

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4 Comments

user2340612 Over a year ago

I think the OP should not use either manual formatting or data classes, but both of them: WeatherData looks like a simple data container, so a data class would perfectly fit the use case. Also, I think manual formatting is better than overriding toString, since the latter should be used to return "a string representation of the object", not something specific to a specific use case

Alex Over a year ago

it still gives me an error on the "main" word "Unresolved reference main"

Akaki Kapanadze Over a year ago

weatherFor.weather is a collection of WeatherData objects, you can iterate over it. for example: holder?.view?.textWeather?.text ="weather ${weatherFor.weather.map{it.main}.joinToString(", ")}"

Alex Over a year ago

@akaki Thank you so much!!(If you want edit your post and put the answer you gave me now on it!)

shkschneider · Accepted Answer · 2018-08-20 12:04:33Z

0

You need to overwrite WeatherData.toString() to have a hand on what's displayed.

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

    override fun toString(): String {
        return "$main $icon"
    }

}

Further more you should use a RecyclerView with a ViewHolder to handle properties one-by-one and enable more complex layouts. If needed.

answered Aug 20, 2018 at 12:04

shkschneider

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1 Comment

Alex Over a year ago

Ok but how can i get only the main or only the icon??

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