AlertDialog kotlin android

alertdialog

package com.example.alerdialog

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AlertDialog

class MainActivity : AppCompatActivity() {
    lateinit var bottom:Button
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        init()
    }

    fun init(){
        bindView()
        bottom.setOnClickListener {
            var builder = AlertDialog.Builder(this)
            builder.setPositiveButton(R.string.yes){_,_ -> finish()}
            builder.setNegativeButton(R.string.no){_,_ -> }
            builder.setIcon(android.R.drawable.ic_dialog_alert)
            builder.setTitle("Quit App")
            builder.setMessage("are you sure to quit app?")
            var alertDialog:AlertDialog = builder.create()
            alertDialog.show()
            builder.show()

        }
    }

    fun bindView(){
        bottom = findViewById(R.id.btndialog)
    }
}