Xamarin.Android 的自动完成

  • 项目

AutoCompleteTextView 是一个可编辑的文本视图元素，可以在用户键入时自动显示完成建议。 建议列表显示在下拉菜单中，用户可以从菜单中选择一个项来替换编辑框的内容。

Example of Auto Complete

概述

要创建提供自动完成建议的文本输入小组件，请使用 AutoCompleteTextView 小组件。 建议是通过 ArrayAdapter 从与该小组件关联的字符串集合接收的。

在本教程中，你将创建一个 提供国家/地区名称建议的 AutoCompleteTextView 小组件。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="5dp">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Country" />
    <AutoCompleteTextView android:id="@+id/autocomplete_country"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="5dp"/>
</LinearLayout>

TextView 是一个标签，用于引入 AutoCompleteTextView 小组件。

教程

启动名为 HelloAutoComplete 的新项目。

创建名为 list_item.xml 的 XML 文件并将其保存在“资源/布局”文件夹中。 将此文件的生成操作设置为 AndroidResource。 编辑文件，如下所示：

<?xml version="1.0" encoding="utf-8"?>

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp"
    android:textSize="16sp"
    android:textColor="#000">
</TextView>

此文件定义了一个简单的 TextView，它将用于显示在建议列表中的每个项。

打开 Resources/Layout/Main.axml 并插入以下内容：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="5dp">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Country" />
    <AutoCompleteTextView android:id="@+id/autocomplete_country"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="5dp"/>
</LinearLayout>

打开 MainActivity.cs 并插入 OnCreate() 方法的代码：

protected override void OnCreate (Bundle bundle)
{
    base.OnCreate (bundle);

    // Set our view from the "Main" layout resource
    SetContentView (Resource.Layout.Main);

    AutoCompleteTextView textView = FindViewById<AutoCompleteTextView> (Resource.Id.autocomplete_country);
    var adapter = new ArrayAdapter<String> (this, Resource.Layout.list_item, COUNTRIES);

    textView.Adapter = adapter;
}

将内容视图设置为 main.xml 布局后，将会使用 FindViewById 从布局中捕获 AutoCompleteTextView 小组件。 然后，将会初始化一个新的 ArrayAdapter，以将 list_item.xml 布局绑定到 COUNTRIES 字符串数组中的每个列表项（将在下一步中定义）。 最后，调用 SetAdapter() 将 ArrayAdapter 与 AutoCompleteTextView 小组件相关联，以便字符串数组填充建议列表。

在 MainActivity 类中，添加该字符串数组：

static string[] COUNTRIES = new string[] {
  "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
  "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
  "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
  "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium",
  "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia",
  "Bosnia and Herzegovina", "Botswana", "Bouvet Island", "Brazil", "British Indian Ocean Territory",
  "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi",
  "Cote d'Ivoire", "Cambodia", "Cameroon", "Canada", "Cape Verde",
  "Cayman Islands", "Central African Republic", "Chad", "Chile", "China",
  "Christmas Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo",
  "Cook Islands", "Costa Rica", "Croatia", "Cuba", "Cyprus", "Czech Republic",
  "Democratic Republic of the Congo", "Denmark", "Djibouti", "Dominica", "Dominican Republic",
  "East Timor", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea",
  "Estonia", "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji", "Finland",
  "Former Yugoslav Republic of Macedonia", "France", "French Guiana", "French Polynesia",
  "French Southern Territories", "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar",
  "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
  "Guyana", "Haiti", "Heard Island and McDonald Islands", "Honduras", "Hong Kong", "Hungary",
  "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Israel", "Italy", "Jamaica",
  "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",
  "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
  "Macau", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands",
  "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
  "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",
  "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand",
  "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "North Korea", "Northern Marianas",
  "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru",
  "Philippines", "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",
  "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe", "Saint Helena",
  "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon",
  "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Saudi Arabia", "Senegal",
  "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands",
  "Somalia", "South Africa", "South Georgia and the South Sandwich Islands", "South Korea",
  "Spain", "Sri Lanka", "Sudan", "Suriname", "Svalbard and Jan Mayen", "Swaziland", "Sweden",
  "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "The Bahamas",
  "The Gambia", "Togo", "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
  "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",
  "Ukraine", "United Arab Emirates", "United Kingdom",
  "United States", "United States Minor Outlying Islands", "Uruguay", "Uzbekistan",
  "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Wallis and Futuna", "Western Sahara",
  "Yemen", "Yugoslavia", "Zambia", "Zimbabwe"
};

这是下拉列表中将会提供的建议列表，只要用户在 AutoCompleteTextView 小组件中键入内容即可显示。

运行该应用程序。 键入时，应会看到如下所示的内容：

Example auto-complete screenshot listing names that contain

更多信息

请注意，使用硬编码字符串数组并不是建议的设计做法，因为应用程序代码应专注于行为，而不是内容。 应用程序内容（如字符串）应从代码外部化，以便更轻松地对内容进行修改，并为本地化内容提供便利。 本教程使用硬编码字符串只是为了简便起见，并专注于 AutoCompleteTextView 小组件。 相反，应用程序应在 XML 文件中声明此类字符串数组。 这可以通过项目 res/values/strings.xml 文件中的 <string-array> 资源来完成。 例如：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="countries_array">
        <item>Bahrain</item>
        <item>Bangladesh</item>
        <item>Barbados</item>
        <item>Belarus</item>
        <item>Belgium</item>
        <item>Belize</item>
        <item>Benin</item>
    </string-array>
</resources>

要将这些资源字符串用于 ArrayAdapter，请将原始 ArrayAdapter 构造函数行替换为以下内容：

string[] countries = Resources.GetStringArray (Resource.array.countries_array);
var adapter = new ArrayAdapter<String> (this, Resource.layout.list_item, countries);

参考

本页的部分内容是根据 Android 开放源代码项目创建和共享的工作进行的修改，并根据知识共享署名 2.5 通用许可协议中的条款进行使用。 本教程基于 Android 自动完成教程*。