Android对话框

layout.xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    <Button
        android:id="@+id/bt_alert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="显示对话框！"


        />
    <Button
        android:id="@+id/btn_single"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="这是一个单选按钮"
        />
</LinearLayout>

activity.java文件

package com.example.myapplication;

import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

public class AlertDialog extends AppCompatActivity implements View.OnClickListener{
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_alert);
        Button bt_alert=findViewById(R.id.bt_alert);
        Button btn_single=findViewById(R.id.btn_single);
        bt_alert.setOnClickListener(this);
        btn_single.setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        androidx.appcompat.app.AlertDialog.Builder builder=new androidx.appcompat.app.AlertDialog.Builder(this);
        switch (v.getId())
        {
            case R.id.bt_alert:
                builder.setTitle("对话框").setIcon(R.mipmap.ic_launcher).setMessage("Drink some small beer!")
                        .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(AlertDialog.this,"Yes,your treat!",Toast.LENGTH_SHORT).show();
                            }
                        })
                        .setNegativeButton("No", new DialogInterface.OnClickListener() {
                            @Override
                            public void onClick(DialogInterface dialog, int which) {
                                Toast.makeText(AlertDialog.this,"I've no time,sorry!",Toast.LENGTH_SHORT).show();
                            }
                        });
            case R.id.btn_single:
                builder.setTitle("单选对话框").setIcon(R.mipmap.ic_launcher).setSingleChoiceItems(new String[]{}, 0, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        Toast.makeText(AlertDialog.this,"选中的",Toast.LENGTH_SHORT).show();
                    }
                });
        }
    }
}