I’m new to android development, I decided to write a music player, but it gives an error in the lines recycler_view.LayoutManager = LayoutManager and in recycler_view.adapter = songListAdapter. I don’t understand what the problem might be, could those who know tell me? Here is the code from MainActivity:

package com.example.zevamusic

import android.annotation.SuppressLint
import android.database.Cursor
import android.os.Bundle
import android.provider.MediaStore
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.LinearLayoutManager
import com.example.zevamusic.adapters.SongListAdapter
import com.example.zevamusic.model.SongModel
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    var songModelData:ArrayList<SongModel> = ArrayList()
    var songListAdapter:SongListAdapter?=null

    @SuppressLint("Range")
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        var songCursor: Cursor? = contentResolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
            null,null,null,null)
        while (songCursor!=null && songCursor.moveToNext()){
            var songName = songCursor.getString(songCursor.getColumnIndex(MediaStore.Audio.Media.TITLE))
            var songDuration = songCursor.getString(songCursor.getColumnIndex(MediaStore.Audio.Media.DURATION))
            songModelData.add(SongModel(songName,songDuration))
        }
        songListAdapter = SongListAdapter(songModelData)
        var layoutManager = LinearLayoutManager(applicationContext)
        recycler_view.LayoutManager = layoutManager
        recycler_view.adapter = songListAdapter
    }
}

Here is the code from SongListAdapter:

package com.example.zevamusic.adapters

import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import com.example.zevamusic.R
import com.example.zevamusic.model.SongModel

class SongListAdapter(SongModel:ArrayList<SongModel>):RecyclerView.Adapter<SongListAdapter.SongListViewHolder>() {

    var mSongModel = SongModel

    override fun getItemCount(): Int {
        return mSongModel.size
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SongListViewHolder {
        var view = LayoutInflater.from(parent!!.context).inflate(R.layout.music_row,parent,false)
        return SongListViewHolder(view)
    }

    override fun onBindViewHolder(holder: SongListViewHolder, position: Int) {
        var model = mSongModel[position]
        var songName = model.mSongName
        var songDuration = model.mSongDuration
        holder!!.songTV.text = songName
        holder.durationTV.text = songDuration
    }



    class SongListViewHolder(itemView: View):RecyclerView.ViewHolder(itemView){
        var songTV:TextView
        var durationTV:TextView
        var albumnAtr:ImageView
        init {
            songTV = itemView.findViewById(R.id.song_name_tv)
            durationTV = itemView.findViewById(R.id.song_duration_tv)
            albumnAtr = itemView.findViewById(R.id.al_image_view)

        }
    }
}

Here is the code from SongModel:

package com.example.zevamusic.model

class SongModel(songName: String,songDuration:String) {
    var mSongName = songName
    var mSongDuration = songDuration

}

I am making this application based on a video clip, I noticed in it the import of which I did not have(import kotlinx.android.synthetic.main.activity_main.*), I decided to add it, but for some reason the word android is lit in red in this import and I tried to fix the problem in import, but I still didn’t figure out what the problem was.