需要注意的两点:
1. 在setIcon时,需要使用setTitle方法,否则icon不会显示
2.如果同时调用setMessage 和 setItems(或者setSingleChoiceItems setMultiChoiceItems)函数会导致dialog没有显示内容
============================================================
AlertDialog的构造方法全部是Protected的,所以不能直接通过new一个AlertDialog来创建出一个AlertDialog。
要创建一个AlertDialog,就要用到AlertDialog.Builder中的create()方法。
使用AlertDialog.Builder创建对话框需要了解以下几个方法:
setTitle :为对话框设置标题
 setIcon :为对话框设置图标
 setMessage:为对话框设置内容
 setView : 给对话框设置自定义样式
 setItems :设置对话框要显示的一个list,一般用于显示几个命令时
 setMultiChoiceItems :用来设置对话框显示一系列的复选框
 setNeutralButton    :普通按钮
setPositiveButton   :给对话框添加"Yes"按钮
 setNegativeButton :对话框添加"No"按钮
 create : 创建对话框
 show :显示对话框
 一、简单的AlertDialog
下面,创建一个简单的ALertDialog并显示它:
 [java]  package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.os.Bundle; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("对话框的标题"). 
                 setMessage("对话框的内容"). 
                 setIcon(R.drawable.ic_launcher). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.os.Bundle;
public class Dialog_AlertDialogDemoActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
  Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("对话框的标题").
     setMessage("对话框的内容").
     setIcon(R.drawable.ic_launcher).
     create();
   alertDialog.show();
  }
 }运行结果如下:

 二、带按钮的AlertDialog
上面的例子很简单,下面我们在这个AlertDialog上面加几个Button,实现删除操作的提示对话框
 [java] package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.content.DialogInterface; 
 import android.os.Bundle; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("确定删除?"). 
                 setMessage("您确定删除该条信息吗?"). 
                 setIcon(R.drawable.ic_launcher). 
                 setPositiveButton("确定", new DialogInterface.OnClickListener() { 
                      
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 setNegativeButton("取消", new DialogInterface.OnClickListener() { 
                      
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 setNeutralButton("查看详情", new DialogInterface.OnClickListener() { 
                      
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
public class Dialog_AlertDialogDemoActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
  Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("确定删除?").
     setMessage("您确定删除该条信息吗?").
     setIcon(R.drawable.ic_launcher).
     setPositiveButton("确定", new DialogInterface.OnClickListener() {
      
      @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     setNegativeButton("取消", new DialogInterface.OnClickListener() {
      
      @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     setNeutralButton("查看详情", new DialogInterface.OnClickListener() {
      
      @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     create();
   alertDialog.show();
  }
 }在这个例子中,我们定义了三个按钮,分别是"Yes"按钮,"No"按钮以及一个普通按钮,每个按钮都有onClick事件,TODO的地方可以放点了按钮之后想要做的一些处理
看一下运行结果:

 可以看到三个按钮添加到了AlertDialog上,三个没有添加事件处理的按钮,点了只是关闭对话框,没有任何其他操作。
三、类似ListView的AlertDialog
 用setItems(CharSequence[] items, final OnClickListener listener)方法来实现类似ListView的AlertDialog
第一个参数是要显示的数据的数组,第二个参数是点击某个item的触发事件
 [java] package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.content.DialogInterface; 
 import android.os.Bundle; 
 import android.widget.Toast; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" }; 
  
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("你喜欢吃哪种水果?"). 
                 setIcon(R.drawable.ic_launcher) 
                 .setItems(arrayFruit, new DialogInterface.OnClickListener() { 
   
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         Toast.makeText(Dialog_AlertDialogDemoActivity.this, arrayFruit[which], Toast.LENGTH_SHORT).show(); 
                     } 
                 }). 
                 setNegativeButton("取消", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.widget.Toast;
public class Dialog_AlertDialogDemoActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" };
  Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("你喜欢吃哪种水果?").
     setIcon(R.drawable.ic_launcher)
     .setItems(arrayFruit, new DialogInterface.OnClickListener() {
  
      @Override
      public void onClick(DialogInterface dialog, int which) {
       Toast.makeText(Dialog_AlertDialogDemoActivity.this, arrayFruit[which], Toast.LENGTH_SHORT).show();
      }
     }).
     setNegativeButton("取消", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     create();
   alertDialog.show();
  }
 }运行结果如下:

四、类似RadioButton的AlertDialog
 用setSingleChoiceItems(CharSequence[] items, int checkedItem, final OnClickListener listener)方法来实现类似RadioButton的AlertDialog
第一个参数是要显示的数据的数组,第二个参数是初始值(初始被选中的item),第三个参数是点击某个item的触发事件
在这个例子里面我们设了一个selectedFruitIndex用来记住选中的item的index
 [java] package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.content.DialogInterface; 
 import android.os.Bundle; 
 import android.widget.Toast; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
      
     private int selectedFruitIndex = 0; 
      
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" }; 
  
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("你喜欢吃哪种水果?"). 
                 setIcon(R.drawable.ic_launcher) 
                 .setSingleChoiceItems(arrayFruit, 0, new DialogInterface.OnClickListener() { 
   
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         selectedFruitIndex = which; 
                     } 
                 }). 
                 setPositiveButton("确认", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         Toast.makeText(Dialog_AlertDialogDemoActivity.this, arrayFruit[selectedFruitIndex], Toast.LENGTH_SHORT).show(); 
                     } 
                 }). 
                 setNegativeButton("取消", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.widget.Toast;
public class Dialog_AlertDialogDemoActivity extends Activity {
  
  private int selectedFruitIndex = 0;
  
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" };
  Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("你喜欢吃哪种水果?").
     setIcon(R.drawable.ic_launcher)
     .setSingleChoiceItems(arrayFruit, 0, new DialogInterface.OnClickListener() {
  
      @Override
      public void onClick(DialogInterface dialog, int which) {
       selectedFruitIndex = which;
      }
     }).
     setPositiveButton("确认", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       Toast.makeText(Dialog_AlertDialogDemoActivity.this, arrayFruit[selectedFruitIndex], Toast.LENGTH_SHORT).show();
      }
     }).
     setNegativeButton("取消", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     create();
   alertDialog.show();
  }
 }
运行结果如下:

 五、类似CheckBox的AlertDialog
 用setMultiChoiceItems(CharSequence[] items, boolean[] checkedItems, final OnMultiChoiceClickListener listener)方法来实现类似CheckBox的AlertDialog
 第一个参数是要显示的数据的数组,第二个参数是选中状态的数组,第三个参数是点击某个item的触发事件
 [java] package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.content.DialogInterface; 
 import android.os.Bundle; 
 import android.widget.Toast; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" }; 
         final boolean[] arrayFruitSelected = new boolean[] {true, true, false, false}; 
  
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("你喜欢吃哪种水果?"). 
                 setIcon(R.drawable.ic_launcher) 
                 .setMultiChoiceItems(arrayFruit, arrayFruitSelected, new DialogInterface.OnMultiChoiceClickListener() { 
                      
                     @Override 
                     public void onClick(DialogInterface dialog, int which, boolean isChecked) { 
                         arrayFruitSelected[which] = isChecked; 
                     } 
                 }). 
                 setPositiveButton("确认", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         StringBuilder stringBuilder = new StringBuilder(); 
                         for (int i = 0; i < arrayFruitSelected.length; i++) { 
                             if (arrayFruitSelected[i] == true) 
                             { 
                                 stringBuilder.append(arrayFruit[i] + "、"); 
                             } 
                         } 
                         Toast.makeText(Dialog_AlertDialogDemoActivity.this, stringBuilder.toString(), Toast.LENGTH_SHORT).show(); 
                     } 
                 }). 
                 setNegativeButton("取消", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.widget.Toast;
public class Dialog_AlertDialogDemoActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
  final String[] arrayFruit = new String[] { "苹果", "橘子", "草莓", "香蕉" };
   final boolean[] arrayFruitSelected = new boolean[] {true, true, false, false};
  Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("你喜欢吃哪种水果?").
     setIcon(R.drawable.ic_launcher)
     .setMultiChoiceItems(arrayFruit, arrayFruitSelected, new DialogInterface.OnMultiChoiceClickListener() {
      
      @Override
      public void onClick(DialogInterface dialog, int which, boolean isChecked) {
       arrayFruitSelected[which] = isChecked;
      }
     }).
     setPositiveButton("确认", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       StringBuilder stringBuilder = new StringBuilder();
       for (int i = 0; i < arrayFruitSelected.length; i++) {
        if (arrayFruitSelected[i] == true)
        {
         stringBuilder.append(arrayFruit[i] + "、");
        }
       }
       Toast.makeText(Dialog_AlertDialogDemoActivity.this, stringBuilder.toString(), Toast.LENGTH_SHORT).show();
      }
     }).
     setNegativeButton("取消", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     create();
   alertDialog.show();
  }
 }运行结果如下:

六、自定义View的AlertDialog
 有时候我们不能满足系统自带的AlertDialog风格,就比如说我们要实现一个Login画面,有用户名和密码,这时我们就要用到自定义View的AlertDialog
先创建Login画面的布局文件
[html] <?xml version="1.0" encoding="utf-8"?> 
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     android:layout_width="fill_parent" 
     android:layout_height="fill_parent" 
     android:orientation="vertical" > 
  
     <LinearLayout 
         android:layout_width="fill_parent" 
         android:layout_height="wrap_content" 
         android:gravity="center" > 
  
         <TextView 
             android:layout_width="0dip" 
             android:layout_height="wrap_content" 
             android:layout_weight="1" 
             android:text="@string/user" /> 
  
         <EditText 
             android:layout_width="0dip" 
             android:layout_height="wrap_content" 
             android:layout_weight="1" /> 
     </LinearLayout> 
  
     <LinearLayout 
         android:layout_width="fill_parent" 
         android:layout_height="wrap_content" 
         android:gravity="center" > 
  
         <TextView 
             android:layout_width="0dip" 
             android:layout_height="wrap_content" 
             android:layout_weight="1" 
             android:text="@string/passward" /> 
  
         <EditText 
             android:layout_width="0dip" 
             android:layout_height="wrap_content" 
             android:layout_weight="1" /> 
     </LinearLayout> 
  
 </LinearLayout> 
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:orientation="vertical" >
    <LinearLayout
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:gravity="center" >
        <TextView
             android:layout_width="0dip"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:text="@string/user" />
        <EditText
             android:layout_width="0dip"
             android:layout_height="wrap_content"
             android:layout_weight="1" />
     </LinearLayout>
    <LinearLayout
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:gravity="center" >
        <TextView
             android:layout_width="0dip"
             android:layout_height="wrap_content"
             android:layout_weight="1"
             android:text="@string/passward" />
        <EditText
             android:layout_width="0dip"
             android:layout_height="wrap_content"
             android:layout_weight="1" />
     </LinearLayout>
</LinearLayout>
 然后在Activity里面把Login画面的布局文件添加到AlertDialog上
[java] package com.tianjf; 
  
 import android.app.Activity; 
 import android.app.AlertDialog; 
 import android.app.Dialog; 
 import android.content.DialogInterface; 
 import android.os.Bundle; 
 import android.view.LayoutInflater; 
 import android.view.View; 
  
 public class Dialog_AlertDialogDemoActivity extends Activity { 
     /** Called when the activity is first created. */ 
     @Override 
     public void onCreate(Bundle savedInstanceState) { 
         super.onCreate(savedInstanceState); 
         setContentView(R.layout.main); 
  
         // 取得自定义View  
         LayoutInflater layoutInflater = LayoutInflater.from(this); 
         View myLoginView = layoutInflater.inflate(R.layout.login, null); 
          
         Dialog alertDialog = new AlertDialog.Builder(this). 
                 setTitle("用户登录"). 
                 setIcon(R.drawable.ic_launcher). 
                 setView(myLoginView). 
                 setPositiveButton("登录", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 setNegativeButton("取消", new DialogInterface.OnClickListener() { 
  
                     @Override 
                     public void onClick(DialogInterface dialog, int which) { 
                         // TODO Auto-generated method stub  
                     } 
                 }). 
                 create(); 
         alertDialog.show(); 
     } 
 } 
 package com.tianjf;
import android.app.Activity;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
public class Dialog_AlertDialogDemoActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.main);
  // 取得自定义View
   LayoutInflater layoutInflater = LayoutInflater.from(this);
   View myLoginView = layoutInflater.inflate(R.layout.login, null);
   
   Dialog alertDialog = new AlertDialog.Builder(this).
     setTitle("用户登录").
     setIcon(R.drawable.ic_launcher).
     setView(myLoginView).
     setPositiveButton("登录", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     setNegativeButton("取消", new DialogInterface.OnClickListener() {
     @Override
      public void onClick(DialogInterface dialog, int which) {
       // TODO Auto-generated method stub
      }
     }).
     create();
   alertDialog.show();
  }
 }运行结果如下:


















