Can't figure out what I have to do, to create a ListView by using ArrayAdapter. So far here's my code:

class GetSongListAsync(private val activity: LastSongs) : AsyncTask<Void, Void, Array<String>>() {
        override fun doInBackground(vararg params: Void): Array<String> {
            val url =
                URL("https://vivalaresistance.ru/radio/stuff/vlrradiobot.php?type=getPlaylist")
            val connection = url.openConnection() as HttpURLConnection
            connection.requestMethod = "GET"
            connection.connect()

            val songList = BufferedReader(InputStreamReader(connection.inputStream, "windows-1251"))

            connection.disconnect()
            return songList
                .readText()
                .replace("и&#774;", "й")
                .replace("И&#774;", "Й")
                .split("\n").dropLast(1).toTypedArray()
        }

        override fun onPostExecute(result: Array<String>) {
            super.onPostExecute(result)
            val list = LastSongs().view?.findViewById<ListView>(R.id.list)
            val arrayAdapter = ArrayAdapter(activity.requireContext(), android.R.layout.simple_list_item_1, result)
            list?.adapter = arrayAdapter
        }
    }

Right now the app is crashing everytime I'm switching to LastSongs fragment and I'm getting java.lang.IllegalStateException: Fragment LastSongs{79211d9} (2b2b2711-f9a8-4352-92ec-55a25a224ea0) not attached to a context.

If I comment three lines and try to Log the result, everything is fine. The result is exactly what i need.

override fun onPostExecute(result: Array<String>) {
            super.onPostExecute(result)
            Log.d("Songs", result.joinToString("; "))
            // val list = LastSongs().view?.findViewById<ListView>(R.id.list)
            // val arrayAdapter = ArrayAdapter(activity.requireContext(), android.R.layout.simple_list_item_1, result)
            // list?.adapter = arrayAdapter
        }

So far I find, that the problem is with activity.requireContext(). I'm making a mistake that I can't understand. How can I get the right context here?

CodePudding user response：

Looks like your code isn't providing the correct params, if you are using the androidx.fragment.app.Fragment you can simply call requireContext() or requireActivity()

private View view;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
   view = inflater.inflate(R.layout.fragment_page, container, false);
   return view;
}

val list = view?.findViewById<ListView>(R.id.list)
val arrayAdapter = ArrayAdapter(view.getContext(), android.R.layout.simple_list_item_1, counties)```


Please check your imports.

CodePudding user response：

I finally fixed it. I added two parameters to my GetSongListAsync class: one for context and one for list. Now it looks like this:

class GetSongListAsync(private val context: Context, private val list: ListView) : AsyncTask<Void, Void, Array<String>>() {
        override fun doInBackground(vararg params: Void): Array<String> {
            *stuff*
        }

        override fun onPostExecute(result: Array<String>) {
            super.onPostExecute(result)
            val arrayAdapter = ArrayAdapter(context, android.R.layout.simple_list_item_1, result)
            list.adapter = arrayAdapter
        }
    }

Now every time I'm calling this class from view, I have to add this parameters.

    val reqCon = requireContext()
    val swipe: SwipeRefreshLayout = view.findViewById(R.id.swipe)
    val list = view.findViewById<ListView>(R.id.list)

    swipe.setOnRefreshListener {
        GetSongListAsync(reqCon, list).execute()
        swipe.isRefreshing = false
    }

Maybe not the best way to do it, but it works.