andorid之AlertDialog的实现

package com.example.administrator.myapplication;

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

public class MainActivity extends AppCompatActivity {

    public String[] list = new String[]{"zhangsan", "lisi", "wangwu", "zhaoliu"};
    public boolean[] checked = new boolean[]{false, true, false, true};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        View.OnClickListener onClickListener = new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                AlertDialog alertDialog =
                        new AlertDialog.Builder(MainActivity.this).create();
                alertDialog.setTitle("title");
                alertDialog.setMessage("this is a message");
                alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "OK", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(MainActivity.this, "OK click", Toast.LENGTH_SHORT).show();
                    }
                });
                alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                });
                alertDialog.show();
            }
        };
        Button btn1 = (Button)findViewById(R.id.btn1);
        btn1.setOnClickListener(onClickListener);
        Button btn2 = (Button)findViewById(R.id.btn2);
        btn2.setOnClickListener(onClickListener);

        Button btn3 = (Button)findViewById(R.id.btn3);
        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setItems(list, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(MainActivity.this, list[i] + "clicked", Toast.LENGTH_SHORT).show();
                    }
                });
                builder.create().show();
            }
        });
        Button btn4 = (Button)findViewById(R.id.btn4);
        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setSingleChoiceItems(list, 0, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        Toast.makeText(MainActivity.this, list[i] + "clicked", Toast.LENGTH_SHORT).show();
                    }
                });
                builder.create().show();
            }
        });
        Button btn5 = (Button)findViewById(R.id.btn5);
        btn5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
                builder.setMultiChoiceItems(list, checked, new DialogInterface.OnMultiChoiceClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i, boolean b) {
                        if(b){
                            Toast.makeText(MainActivity.this, list[i] + "checked", Toast.LENGTH_SHORT).show();
                        }
                        else{
                            Toast.makeText(MainActivity.this, list[i] + "checked", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
                builder.create().show();
            }
        });
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.administrator.myapplication.MainActivity"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="btn1"/>
    <Button
        android:id="@+id/btn2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="btn2"
        />
    <Button
        android:id="@+id/btn3"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="btn3"/>
    <Button
        android:id="@+id/btn4"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="btn4"/>
    <Button
        android:id="@+id/btn5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="btn5"/>

</LinearLayout>