AlertDialog的使用

package com.example.hndx.myapplication;

import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = (Button) findViewById(R.id.btn1);
        Button button1 = (Button) findViewById(R.id.btn2);
        Button button2 = (Button) findViewById(R.id.btn3);
        Button button3 = (Button) findViewById(R.id.btn4);
        Button button4 = (Button) findViewById(R.id.btn5);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                showDialog();
            }
        });
    }
    private void showDialog(){
        //android.support.v7.app.AlertDialog.Builder localBuilder = new android.support.v7.app.AlertDialog.Builder(this);
        AlertDialog localBuilder =null;
        localBuilder =new AlertDialog.Builder(this).create();
        localBuilder.setTitle("简单对话框");
        localBuilder.setIcon(R.drawable.ic_launcher_foreground);
        localBuilder.setMessage("提示信息？");
        localBuilder.setButton(DialogInterface.BUTTON1, "确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
        });
        localBuilder.show();
    }
}

<?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"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="AlertDialog"/>
    <Button
        android:id="@+id/btn1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="确认对话框"
        android:textSize="20dp"/>
    <Button
        android:id="@+id/btn2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="列表对话框"
        android:textSize="20dp"/>
    <Button
        android:id="@+id/btn3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="单选对话框"
        android:textSize="20dp"/>
    <Button
        android:id="@+id/btn4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="多选对话框"
        android:textSize="20dp"/>
    <Button
        android:id="@+id/btn5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="自定义对话框"
        android:textSize="20dp"/>


</LinearLayout>