跳转到相应内容

最常访问

最近访问

navigation

Re-using Layouts with <include/>

Although Android offers a variety of widgets to provide small and re-usable interactive elements, you might also need to re-use larger components that require a special layout. To efficiently re-use complete layouts, you can use the <include/> and <merge/> tags to embed another layout inside the current layout.

Reusing layouts is particularly powerful as it allows you create reusable complex layouts. For example, a yes/no button panel, or custom progress bar with description text. It also means that any elements of your application that are common across multiple layouts can be extracted, managed separately, then included in each layout. So while you can create individual UI components by writing a custom View, you can do it even more easily by re-using a layout file.

Create a Re-usable Layout

If you already know the layout that you want to re-use, create a new XML file and define the layout. For example, here's a layout that defines a title bar to be included in each activity (titlebar.xml):

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/titlebar_bg"
    tools:showIn="@layout/activity_main" >

    <ImageView android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:src="@drawable/gafricalogo" />
</FrameLayout>

The root View should be exactly how you'd like it to appear in each layout to which you add this layout.

Note: The tools:showIn attribute in the XML above is a special attribute that is removed during compilation and used only at design-time in Android Studio—it specifies a layout that includes this file, so you can preview (and edit) this file as it appears while embedded in a parent layout.

Use the <include> Tag

Inside the layout to which you want to add the re-usable component, add the <include/> tag. For example, here's a layout that includes the title bar from above:

Here's the layout file:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/app_bg"
    android:gravity="center_horizontal">

    <include layout="@layout/titlebar"/>

    <TextView android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:text="@string/hello"
              android:padding="10dp" />

    ...

</LinearLayout>

You can also override all the layout parameters (any android:layout_* attributes) of the included layout's root view by specifying them in the <include/> tag. For example:

<include android:id="@+id/news_title"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         layout="@layout/title"/>

However, if you want to override layout attributes using the <include> tag, you must override both android:layout_height and android:layout_width in order for other layout attributes to take effect.

Use the <merge> Tag

The <merge /> tag helps eliminate redundant view groups in your view hierarchy when including one layout within another. For example, if your main layout is a vertical LinearLayout in which two consecutive views can be re-used in multiple layouts, then the re-usable layout in which you place the two views requires its own root view. However, using another LinearLayout as the root for the re-usable layout would result in a vertical LinearLayout inside a vertical LinearLayout. The nested LinearLayout serves no real purpose other than to slow down your UI performance.

To avoid including such a redundant view group, you can instead use the <merge> element as the root view for the re-usable layout. For example:

<merge xmlns:android="http://schemas.android.com/apk/res/android">

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/add"/>

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/delete"/>

</merge>

Now, when you include this layout in another layout (using the <include/> tag), the system ignores the <merge> element and places the two buttons directly in the layout, in place of the <include/> tag.

此网站会使用 Cookie 来存储您在此网站上指定的语言和显示选项偏好设置。

获取最新的 Android Developers 资讯和提示,助您在 Google Play 上取得成功。

* 必填字段

成功!

在微信上关注 Google Developers

要以浏览此网站吗?

您请求访问的是网页,但是您为此网站设置的语言偏好为

要更改您的语言偏好设置并以浏览此网站吗?如果以后您想要更改语言偏好设置,请使用每个页面底部的语言菜单。

该类需要 或更高的 API 级别

此文档已被隐藏,因为您为该文档选择的 API 级别是 。您可以使用左侧导航栏上方的选择器来更改文档的 API 级别。

要详细了解如何根据您的应用需求指定 API 级别,请参阅支持不同平台版本

Take a short survey?
Help us improve the Android developer experience. (April 2018 — Developer Survey)