<?xml version="1.0" encoding="utf-8"?> <ViewGroupxmlns:android="http://schemas.android.com/apk/res/android"android:id="@[+][package:]id/resource_name"android:layout_height=["dimension" | "match_parent" | "wrap_content"]android:layout_width=["dimension" | "match_parent" | "wrap_content"][ViewGroup-specific attributes] ><Viewandroid:id="@[+][package:]id/resource_name"android:layout_height=["dimension" | "match_parent" | "wrap_content"]android:layout_width=["dimension" | "match_parent" | "wrap_content"][View-specific attributes] ><requestFocus/></View><ViewGroup ><View /></ViewGroup><include layout="@layout/layout_resource"/> </ViewGroup>

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<include>

Includes a layout file into this layout.

attributes:

layout

Layout resource.?Required. Reference to a layout resource.

android:id

Resource ID. Overrides the ID given to the root view in the included layout.

android:layout_height

Dimension or keyword. Overrides the height given to the root view in the included layout. Only effective if?android:layout_width?is also declared.

android:layout_width

Dimension or keyword. Overrides the width given to the root view in the included layout. Only effective if?android:layout_height?is also declared.

You can include any other layout attributes in the?<include>?that are supported by the root element in the included layout and they will override those defined in the root element.

Caution:?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.

Another way to include a layout is to use?ViewStub. It is a lightweight View that consumes no layout space until you explicitly inflate it, at which point, it includes a layout file defined by its?android:layout?attribute. For more information about using?ViewStub, read?Loading Views On Demand.

Note:?One drawback of?ViewStub?is that it doesn’t currently support the?<merge>?tag in the layouts to be inflated.

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?<requestFocus>

Any element representing a?View?object can include this empty element, which gives its parent initial focus on the screen. You can have only one of these elements per file.<3>

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?<merge>

An alternative root element that is not drawn in the layout hierarchy. Using this as the root element is useful when you know that this layout will be placed into a layout that already contains the appropriate parent View to contain the children of the?<merge>?element. This is particularly useful when you plan to include this layout in another layout file using?<include>?and this layout doesn't require a different?ViewGroup?container. For more information about merging layouts, read?Re-using Layouts with <include/>.

From:https://developer.android.com/guide/topics/resources/layout-resource.html

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Define a ViewStub

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ViewStub?is a lightweight view with no dimension that doesn’t draw anything or participate in the layout. As such, it's cheap to inflate and cheap to leave in a view hierarchy. Each?ViewStub?simply needs to include the?android:layout?attribute to specify the layout to inflate.

The following?ViewStub?is for a translucent progress bar overlay. It should be visible only when new items are being imported into the application.

<ViewStubandroid:id="@+id/stub_import"android:inflatedId="@+id/panel_import"android:layout="@layout/progress_overlay"android:layout_width="fill_parent"android:layout_height="wrap_content"android:layout_gravity="bottom" />

Load the ViewStub Layout

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When you want to load the layout specified by the?ViewStub, either set it visible by calling?setVisibility(View.VISIBLE)?or call?inflate().

findViewById(R.id.stub_import)).setVisibility(View.VISIBLE); // or View importPanel = ((ViewStub) findViewById(R.id.stub_import)).inflate();

Note:?The?inflate()?method returns the inflated?View?once complete. so you don't need to call?findViewById()?if you need to interact with the layout.

Once visible/inflated, the?ViewStub?element is no longer part of the view hierarchy. It is replaced by the inflated layout and the ID for the root view of that layout is the one specified by the?android:inflatedId?attribute of the ViewStub. (The ID?android:id?specified for the?ViewStub?is valid only until the?ViewStub?layout is visible/inflated.)

Note:?One drawback of?ViewStub?is that it doesn’t currently support the?<merge>?tag in the layouts to be inflated.

From:?https://developer.android.com/training/improving-layouts/loading-ondemand.html

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