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A dialog is a small window that prompts the user to make a decision or enter additional information. A dialog does not fill the screen and is normally used for modal events that require users to take an action before they can proceed.

java.lang.Object↳     android.app.DialogKnown Direct Subclasses
AlertDialog, CharacterPickerDialog, MediaRouteChooserDialog, MediaRouteControllerDialog, Presentation
Known Indirect Subclasses
DatePickerDialog, ProgressDialog, TimePickerDialog 

1.setPositiveButton(CharSequence text, DialogInterface.OnClickListener listener)
这是一个相当于OK、确定操作的按钮，2.setNegativeButton (CharSequence text, DialogInterface.OnClickListener listener)
这是一个相当于取消操作的按钮。3. setNeutralButton (CharSequence text, DialogInterface.OnClickListener listener)
这个是相当于一个忽略操作的按钮。

button.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){//    通过AlertDialog.Builder这个类来实例化我们的一个AlertDialog的对象AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);//    设置Title的图标
                builder.setIcon(R.drawable.ic_launcher);//    设置Title的内容builder.setTitle("弹出警告框");//    设置Content来显示一个信息builder.setMessage("确定删除吗？");//    设置一个PositiveButtonbuilder.setPositiveButton("确定", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){Toast.makeText(MainActivity.this, "positive: " + which, Toast.LENGTH_SHORT).show();}});//    设置一个NegativeButtonbuilder.setNegativeButton("取消", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){Toast.makeText(MainActivity.this, "negative: " + which, Toast.LENGTH_SHORT).show();}});//    设置一个NeutralButtonbuilder.setNeutralButton("忽略", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){Toast.makeText(MainActivity.this, "neutral: " + which, Toast.LENGTH_SHORT).show();}});//    显示出该对话框
                builder.show();}});

positive:  -1
negative:  -2
neutral:  -3

button2.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View arg0){AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(R.drawable.ic_launcher);builder.setTitle("选择一个城市");//    指定下拉列表的显示数据final String[] cities = {"广州", "上海", "北京", "香港", "澳门"};//    设置一个下拉的列表选择项builder.setItems(cities, new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){Toast.makeText(MainActivity.this, "选择的城市为：" + cities[which], Toast.LENGTH_SHORT).show();}});builder.show();}});

button3.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(R.drawable.ic_launcher);builder.setTitle("请选择性别");final String[] sex = {"男", "女", "未知性别"};//    设置一个单项选择下拉框/*** 第一个参数指定我们要显示的一组下拉单选框的数据集合* 第二个参数代表索引，指定默认哪一个单选框被勾选上，1表示默认'女' 会被勾选上* 第三个参数给每一个单选项绑定一个监听器*/builder.setSingleChoiceItems(sex, 1, new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){Toast.makeText(MainActivity.this, "性别为：" + sex[which], Toast.LENGTH_SHORT).show();}});builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){}});builder.setNegativeButton("取消", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){}});builder.show();}});

button4.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(R.drawable.ic_launcher);builder.setTitle("爱好");final String[] hobbies = {"篮球", "足球", "网球", "斯诺克"};//    设置一个单项选择下拉框/*** 第一个参数指定我们要显示的一组下拉多选框的数据集合* 第二个参数代表哪几个选项被选择，如果是null，则表示一个都不选择，如果希望指定哪一个多选选项框被选择，* 需要传递一个boolean[]数组进去，其长度要和第一个参数的长度相同，例如 {true, false, false, true};* 第三个参数给每一个多选项绑定一个监听器*/builder.setMultiChoiceItems(hobbies, null, new DialogInterface.OnMultiChoiceClickListener(){StringBuffer sb = new StringBuffer(100);@Overridepublic void onClick(DialogInterface dialog, int which, boolean isChecked){if(isChecked){sb.append(hobbies[which] + ", ");}Toast.makeText(MainActivity.this, "爱好为：" + sb.toString(), Toast.LENGTH_SHORT).show();}});builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){}});builder.setNegativeButton("取消", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){}});builder.show();}});

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent" ><EditText android:id="@+id/username"android:layout_width="match_parent"android:layout_height="wrap_content"android:hint="username"/><EditTextandroid:id="@+id/password"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_below="@id/username"android:hint="password"android:inputType="textPassword"/></RelativeLayout>

button5.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v){AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);builder.setIcon(R.drawable.ic_launcher);builder.setTitle("请输入用户名和密码");//    通过LayoutInflater来加载一个xml的布局文件作为一个View对象View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.dialog, null);//    设置我们自己定义的布局文件作为弹出框的Content
                builder.setView(view);final EditText username = (EditText)view.findViewById(R.id.username);final EditText password = (EditText)view.findViewById(R.id.password);builder.setPositiveButton("确定", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){String a = username.getText().toString().trim();String b = password.getText().toString().trim();//    将输入的用户名和密码打印出来Toast.makeText(MainActivity.this, "用户名: " + a + ", 密码: " + b, Toast.LENGTH_SHORT).show();} });builder.setNegativeButton("取消", new DialogInterface.OnClickListener(){@Overridepublic void onClick(DialogInterface dialog, int which){}});builder.show();}});