1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="vertical"
 6     >
 7     <Button
 8         android:id="@+id/bt_alert"
 9         android:layout_width="wrap_content"
10         android:layout_height="wrap_content"
11         android:text="显示对话框！"
12 
13 
14         />
15     <Button
16         android:id="@+id/btn_single"
17         android:layout_width="wrap_content"
18         android:layout_height="wrap_content"
19         android:text="这是一个单选按钮"
20         />
21 </LinearLayout>

 1 package com.example.myapplication;
 2 
 3 import android.content.DialogInterface;
 4 import android.os.Bundle;
 5 import android.view.View;
 6 import android.widget.Button;
 7 import android.widget.Toast;
 8 import androidx.annotation.Nullable;
 9 import androidx.appcompat.app.AppCompatActivity;
10 
11 public class AlertDialog extends AppCompatActivity implements View.OnClickListener{
12     @Override
13     protected void onCreate(@Nullable Bundle savedInstanceState) {
14         super.onCreate(savedInstanceState);
15         setContentView(R.layout.activity_alert);
16         Button bt_alert=findViewById(R.id.bt_alert);
17         Button btn_single=findViewById(R.id.btn_single);
18         bt_alert.setOnClickListener(this);
19         btn_single.setOnClickListener(this);
20     }
21     @Override
22     public void onClick(View v) {
23         androidx.appcompat.app.AlertDialog.Builder builder=new androidx.appcompat.app.AlertDialog.Builder(this);
24         switch (v.getId())
25         {
26             case R.id.bt_alert:
27                 builder.setTitle("对话框").setIcon(R.mipmap.ic_launcher).setMessage("Drink some small beer!")
28                         .setPositiveButton("OK", new DialogInterface.OnClickListener() {
29                             @Override
30                             public void onClick(DialogInterface dialog, int which) {
31                                 Toast.makeText(AlertDialog.this,"Yes,your treat!",Toast.LENGTH_SHORT).show();
32                             }
33                         })
34                         .setNegativeButton("No", new DialogInterface.OnClickListener() {
35                             @Override
36                             public void onClick(DialogInterface dialog, int which) {
37                                 Toast.makeText(AlertDialog.this,"I've no time,sorry!",Toast.LENGTH_SHORT).show();
38                             }
39                         });
40             case R.id.btn_single:
41                 builder.setTitle("单选对话框").setIcon(R.mipmap.ic_launcher).setSingleChoiceItems(new String[]{}, 0, new DialogInterface.OnClickListener() {
42                     @Override
43                     public void onClick(DialogInterface dialog, int which) {
44                         Toast.makeText(AlertDialog.this,"选中的",Toast.LENGTH_SHORT).show();
45                     }
46                 });
47         }
48     }
49 }