안드로이드 popup창

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/popup_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="팝업창"/>

    <TextView
        android:id="@+id/result"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="테스트"
        android:textSize="40sp"/>



</LinearLayout>

package com.gohool.popup;

import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private Button btn;
    private TextView result;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        result = (TextView) findViewById(R.id.result);
        btn = (Button) findViewById(R.id.popup_btn);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                AlertDialog.Builder ad = new AlertDialog.Builder(MainActivity.this);
                ad.setIcon(R.mipmap.ic_launcher); //띄울 거
                ad.setTitle("경고");
                ad.setMessage("님은 존잘입니까?");



                // edit 만들어줘서 팝업창에 view로 넣어줌
                final EditText et = new EditText(MainActivity.this);
                ad.setView(et);

                //edit에서 값을 받아옴
                ad.setPositiveButton("확인", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        String answer = et.getText().toString();
                        result.setText(answer);
                        dialog.dismiss();//닫아라

                    }
                });

                ad.setNegativeButton("취소", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });

                ad.show(); //시작
            }
        });

    }
}