kotlin-migrate-main-activity-kotlin-class-refectored

package dev.bipin.doit

import android.os.Bundle
import android.view.View
import android.widget.ArrayAdapter
import android.widget.EditText
import android.widget.LinearLayout.LayoutParams
import android.widget.ListView
import android.widget.TextView
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AlertDialog.Builder
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.floatingactionbutton.FloatingActionButton

class MainActivity : AppCompatActivity() {

    private val doItList: MutableList<String> = ArrayList()

    private val listItemAdapter: ArrayAdapter<String> by lazy {
        ArrayAdapter(this, android.R.layout.simple_list_item_1, doItList)
    }

    private val listView: ListView by lazy {
        findViewById<ListView>(R.id.listview)
    }

    private val emptyView: TextView by lazy {
        findViewById<TextView>(R.id.empty_view)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        setSupportActionBar(findViewById(R.id.toolbar))
        listView.apply {
            this.adapter = listItemAdapter
        }
        findViewById<FloatingActionButton>(R.id.fab)
                .setOnClickListener { showAddDoItItem() }
        refreshUI()
    }

    private fun refreshUI() {

        if (doItList.size > 0) {
            listView.visibility = View.VISIBLE
            emptyView.visibility = View.GONE
            listItemAdapter.notifyDataSetChanged()
        } else {
            listView.visibility = View.GONE
            emptyView.visibility = View.VISIBLE
        }
    }

    private fun showAddDoItItem() {
        val inputView = EditText(this)
        inputView.hint = "Add Do Item Name"
        val lp = LayoutParams(
                LayoutParams.MATCH_PARENT,
                LayoutParams.WRAP_CONTENT
        )
        lp.setMargins(10, 10, 10, 10)
        inputView.layoutParams = lp
        val alertDialog: AlertDialog = Builder(this)
                .setTitle("Do It")
                .setCancelable(true)
                .setView(inputView)
                .setNegativeButton("Cancel") { dialogInterface, _ -> dialogInterface.dismiss() }
                .setPositiveButton("Add") { dialogInterface, _ ->
                    dialogInterface.dismiss()
                    doItList.add(inputView.text.toString())
                    refreshUI()
                }
                .create()
        alertDialog.show()
    }
}