AlertDialog的構造方法全部是Protected的，所以不能直接通過new一個AlertDialog來創建出一個AlertDialog。

要創建一個AlertDialog，就要用到AlertDialog.Builder中的create()方法。

使用AlertDialog.Builder創建對話框需要了解以下幾個方法：

setTitle ：為對話框設置標題
setIcon ：為對話框設置圖標
setMessage：為對話框設置內容
setView ： 給對話框設置自定義樣式
setItems ：設置對話框要顯示的一個list，一般用于顯示幾個命令時
setMultiChoiceItems ：用來設置對話框顯示一系列的復選框
setNeutralButton ：普通按鈕

setPositiveButton ：給對話框添加"Yes"按鈕
setNegativeButton ：對話框添加"No"按鈕
create ： 創建對話框
show ：顯示對話框
一、簡單的AlertDialog

下面，創建一個簡單的ALertDialog并顯示它：

[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("對話框的標題").
setMessage("對話框的內容").
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("對話框的標題").
setMessage("對話框的內容").
setIcon(R.drawable.ic_launcher).
create();
alertDialog.show();
}
}運行結果如下：

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畫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);

// 取得自定義View
LayoutInflater layoutInflater = LayoutInflater.from(this);
View myLoginView = layoutInflater.inflate(R.layout.login, null);

Dialog alertDialog = new AlertDialog.Builder(this).
setTitle("用戶登錄").
setIcon(R.drawable.ic_launcher).
setView(myLoginView).
setPositiveButton("登錄", 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);

// 取得自定義View
LayoutInflater layoutInflater = LayoutInflater.from(this);
View myLoginView = layoutInflater.inflate(R.layout.login, null);

Dialog alertDialog = new AlertDialog.Builder(this).
setTitle("用戶登錄").
setIcon(R.drawable.ic_launcher).
setView(myLoginView).
setPositiveButton("登錄", 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();
}
}運行結果如下：

摘自 殤雲的專欄

Android的AlertDialog詳解