一、activity_main.java中代码

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2     xmlns:tools="http://schemas.android.com/tools" 3     android:layout_width="match_parent" 4     android:layout_height="match_parent" 5     android:gravity="center" 6     tools:context="com.example.Dialog.MainActivity" > 7     <Button 8         android:onClick="click" 9         android:layout_width="wrap_content"10         android:layout_height="wrap_content"11         android:text="对话框" />12 </LinearLayout>

二、MainActivity.java中的代码
 1 package com.example.Dialog; 2  3 import android.app.Activity; 4 import android.app.AlertDialog; 5 import android.app.AlertDialog.Builder; 6 import android.app.Dialog; 7 import android.content.DialogInterface; 8 import android.content.DialogInterface.OnClickListener; 9 import android.os.Bundle;10 import android.view.KeyEvent;11 import android.view.View;12 import android.widget.Toast;13 14 public class MainActivity extends Activity {15 16     @Override17     protected void onCreate(Bundle savedInstanceState) {18         super.onCreate(savedInstanceState);19         setContentView(R.layout.activity_main);20     }21 22     public void click(View view) {23         AlertDialog.Builder builder = new Builder(this);24         builder.setTitle("提示");25         builder.setIcon(R.drawable.ic_launcher);26         builder.setMessage("是否要进行软件升级");27         // builder.setCancelable(false);28         builder.setPositiveButton("确定", new OnClickListener() {29             @Override30             public void onClick(DialogInterface dialog, int which) {31                 // TODO Auto-generated method stub32                 Toast.makeText(MainActivity.this, "确定被点击了", 0).show();33             }34         });35         builder.setNegativeButton("取消", new OnClickListener() {36 37             @Override38             public void onClick(DialogInterface dialog, int which) {39                 // TODO Auto-generated method stub40                 Toast.makeText(MainActivity.this, "取消被点击了", 0).show();41             }42         });43         builder.create().show();44     }45 46     @Override47     public boolean onKeyDown(int keyCode, KeyEvent event) {48         // TODO Auto-generated method stub49 50         if (keyCode == KeyEvent.KEYCODE_BACK) {51             AlertDialog.Builder builder = new Builder(this);52             builder.setTitle("提示");53             builder.setMessage("确定要退出吗");54             builder.create();55             Dialog dialog;56 57             builder.setPositiveButton("确定", new OnClickListener() {58 59                 @Override60                 public void onClick(DialogInterface dialog, int which) {61                     // TODO Auto-generated method stub62                     dialog.dismiss();63                 }64             });65             builder.setNegativeButton("取消", new OnClickListener() {66 67                 @Override68                 public void onClick(DialogInterface dialog, int which) {69                     // TODO Auto-generated method stub70 71                 }72             });73             dialog = builder.show();74 75         }76         return false;77     }78 }