android.view.InflateException:

Question

android.view.InflateException: строка двоичного XML-файла # 26: попытка вызвать виртуальный метод 'boolean java.lang.String.equals (java.lang.Object)' для ссылки на пустой объект Я создаю приложение для музыкального плеера. Приложение работало нормально, прежде чем я сделал несколько изменений в mainactivity.kt и добавил код для navigationdraweradapter.kt. Теперь, когда я запускаю приложение, отображается экран-заставка, но когда он входит в основную деятельность, приложение вылетает и вышеуказанная ошибка показана. Я приложил код ниже, пожалуйста, помогите. MAINACTIVITY.KT

package com.asr.suno.activities

import android.os.Bundle
import android.support.v4.widget.DrawerLayout
import android.support.v7.app.ActionBarDrawerToggle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.DefaultItemAnimator
import android.support.v7.widget.LinearLayoutManager
import android.support.v7.widget.RecyclerView
import android.support.v7.widget.Toolbar
import com.asr.suno.fragments.MainScreenFragment
import com.asr.suno.R
import com.asr.suno.adapter.NavigationDrawerAdapter

class MainActivity : AppCompatActivity() {

var navigationDrawerIconList: ArrayList<String> = arrayListOf()
var images_for_navdrawer= 
intArrayOf(R.drawable.navigation_allsongs,R.drawable.navigation_favorites,
        R.drawable.navigation_settings,R.drawable.navigation_aboutus)
object Statified {
    var drawerLayout: DrawerLayout? = null
}
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    val toolbar=findViewById<Toolbar>(R.id.toolbar)
    setSupportActionBar(toolbar)
    MainActivity.Statified.drawerLayout=findViewById(R.id.drawer_layout)

    navigationDrawerIconList.add ("All Songs")
    navigationDrawerIconList.add("Favorite")
    navigationDrawerIconList.add("Settings")
    navigationDrawerIconList.add("About Us")

    val toggle=ActionBarDrawerToggle(this@MainActivity, 
MainActivity.Statified.drawerLayout,
            toolbar, R.string.navigation_drawer_open, 
R.string.navigation_drawer_close)
   // MainActivity.Statified.drawerLayout?.setDrawerListener(toggle)
    MainActivity.Statified.drawerLayout?.addDrawerListener(toggle)
    toggle.syncState()
    val mainScreenFragment = MainScreenFragment()
    this.supportFragmentManager
            .beginTransaction()

.add(R.id.details_fragment,mainScreenFragment,"MainScreenFragment")
            .commit()

    var _navigationAdapter = 
NavigationDrawerAdapter(navigationDrawerIconList,images_for_navdrawer,this)
    _navigationAdapter.notifyDataSetChanged()

    var navigation_recycler_view =findViewById<RecyclerView> 
(R.id.navigation_recycler_view)
    navigation_recycler_view.layoutManager= LinearLayoutManager(this)
    navigation_recycler_view.itemAnimator= DefaultItemAnimator()
    navigation_recycler_view.adapter = _navigationAdapter
    navigation_recycler_view.setHasFixedSize(true)
}

override fun onStart() {
    super.onStart()
}
}

NAVIGATIONDRAWERADAPTER.KT

package com.asr.suno.adapter

import android.content.Context
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.RelativeLayout
import android.widget.TextView
import com.asr.suno.R
import com.asr.suno.activities.MainActivity
import com.asr.suno.fragments.AboutUsFragment
import com.asr.suno.fragments.FavoriteFragment
import com.asr.suno.fragments.MainScreenFragment
import com.asr.suno.fragments.SettingsFragment

class 
 NavigationDrawerAdapter(_contentList:ArrayList<String>,
       _getImages:IntArray,_context:Context)
             :RecyclerView.Adapter<NavigationDrawerAdapter.NavViewHolder>(){
var contentList: ArrayList<String>?=null
var getImages: IntArray?=null
var mContext: Context?=null
init {
    this.contentList=_contentList
    this.getImages=_getImages
    this.mContext=_context
}
override fun onCreateViewHolder(parent: ViewGroup?, viewType: Int): 
NavViewHolder {
    var itemView =  
 LayoutInflater.from(parent?.context)
.inflate(R.layout.row_custom_navigationdrawer,parent,false)
    val returnThis=NavViewHolder(itemView)
    return returnThis
}

override fun onBindViewHolder(holder: NavViewHolder?, position: Int) {
    holder?.icon_GET?.setBackgroundResource(getImages?.get(position)as Int)
    holder?.text_GET?.setText(contentList?.get(position))
    holder?.contentHolder?.setOnClickListener({
        if(position==0){
            val mainScreenFragment = MainScreenFragment()
            (mContext as MainActivity).supportFragmentManager
                    .beginTransaction()
                    .replace(R.id.details_fragment,mainScreenFragment)
                    .commit()
        }else if(position==1){

            val favorateFragment = FavoriteFragment()
            (mContext as MainActivity).supportFragmentManager
                    .beginTransaction()
                    .replace(R.id.details_fragment,favorateFragment)
                    .commit()

        }else if(position==2) {

            val settingsFragment = SettingsFragment()
            (mContext as MainActivity).supportFragmentManager
                    .beginTransaction()
                    .replace(R.id.details_fragment,settingsFragment)
                    .commit()
        }else {

            val aboutUsFragment = AboutUsFragment()
            (mContext as MainActivity).supportFragmentManager
                    .beginTransaction()
                    .replace(R.id.details_fragment,aboutUsFragment)
                    .commit()
        }
        MainActivity.Statified.drawerLayout?.closeDrawers()
    })


}
override fun getItemCount(): Int {
    return (contentList as ArrayList).size

}

class NavViewHolder(itemView: View?) : RecyclerView.ViewHolder(itemView) {
    var icon_GET: ImageView? = null
    var text_GET: TextView? = null
    var contentHolder: RelativeLayout? = null

    init {
        icon_GET = itemView?.findViewById(R.id.icon_navdrawer)
        text_GET = itemView?.findViewById(R.id.text_navdrawer)
        contentHolder = 
itemView?.findViewById(R.id.navdrawer_item_content_holder)
    }
}
}