xref: /frameworks/base/docs/html/guide/topics/manifest/activity-alias-element.jd

page.title=<activity-alias>
parent.title=The AndroidManifest.xml File
parent.link=manifest-intro.html
@jd:body

<dl class="xml">
<dt>syntax:</dt>
<dd><pre class="stx">&lt;activity-alias android:<a href="#enabled">enabled</a>=["true" | "false"]
                android:<a href="#exported">exported</a>=["true" | "false"]
                android:<a href="#icon">icon</a>="<i>drawable resource</i>"
                android:<a href="#label">label</a>="<i>string resource</i>"
                android:<a href="#nm">name</a>="<i>string</i>"
                android:<a href="#prmsn">permission</a>="<i>string</i>"
                android:<a href="#trgt">targetActivity</a>="<i>string</i>" &gt;
    . . .
&lt;/activity-alias&gt;</pre></dd>

<dt>contained in:</dt>
<dd><code><a href="{@docRoot}guide/topics/manifest/application-element.html">&lt;application&gt;</a></code></dd>

<dt>can contain:</dt>
<dd><code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html">&lt;intent-filter&gt;</a></code>
<br/><code><a href="{@docRoot}guide/topics/manifest/meta-data-element.html">&lt;meta-data&gt;</a></code></dd>

<dt>description:</dt>
<dd itemprop="description">An alias for an activity, named by the {@code targetActivity}
attribute.  The target must be in the same application as the
alias and it must be declared before the alias in the manifest.

<p>
The alias presents the target activity as a independent entity.
It can have its own set of intent filters, and they, rather than the 
intent filters on the target activity itself, determine which intents 
can activate the target through the alias and how the system
treats the alias.  For example, the intent filters on the alias may 
specify the "<code>{@link android.content.Intent#ACTION_MAIN 
android.intent.action.MAIN}</code>" 
and "<code>{@link android.content.Intent#CATEGORY_LAUNCHER 
android.intent.category.LAUNCHER}</code>" flags, causing it to be 
represented in the application launcher, even though none of the 
filters on the target activity itself set these flags.
</p>

<p>
With the exception of {@code targetActivity}, {@code &lt;activity-alias&gt;} 
attributes are a subset of <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> attributes.  
For attributes in the subset, none of the values set for the target carry over
to the alias.  However, for attributes not in the subset, the values set for 
the target activity also apply to the alias.
</p></dd>

<dt>attributes:</dt>
<dd><dl class="attr">
<dt><a name="enabled"></a>{@code android:enabled}</dt>
<dd>Whether or not the target activity can be instantiated by the system through 
this alias &mdash; "{@code true}" if it can be, and "{@code false}" if not.  
The default value is "{@code true}".

<p>
The <code><a href="{@docRoot}guide/topics/manifest/application-element.html">&lt;application&gt;</a></code> element has its own 
<code><a href="{@docRoot}guide/topics/manifest/application-element.html#enabled">enabled</a></code> attribute that applies to all 
application components, including activity aliases.  The 
<code><a href="{@docRoot}guide/topics/manifest/application-element.html">&lt;application&gt;</a></code> and {@code &lt;activity-alias&gt;} 
attributes must both be "{@code true}" for the system to be able to instantiate 
the target activity through the alias.  If either is "{@code false}", the alias 
does not work.
</p></dd>

<dt><a name="exported"></a>{@code android:exported}</dt>
<dd>Whether or not components of other applications can launch the target activity 
through this alias &mdash; "{@code true}" if they can, and "{@code false}" if not.  
If "{@code false}", the target activity can be launched through the alias only by 
components of the same application as the alias or applications with the same user ID.  

<p>
The default value depends on whether the alias contains intent filters.  The 
absence of any filters means that the activity can be invoked through the alias
only by specifying the exact name of the alias.  This implies that the alias 
is intended only for application-internal use (since others would not know its name)  
&mdash; so the default value is "{@code false}".
On the other hand, the presence of at least one filter implies that the alias 
is intended for external use &mdash; so the default value is "{@code true}".
</p></dd>

<dt><a name="icon"></a>{@code android:icon}</dt>
<dd>An icon for the target activity when presented to users through the alias.  
See the <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> element's 
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html#icon">icon</a></code> attribute for more information.

<dt><a name="label"></a>{@code android:label}</dt>
<dd>A user-readable label for the alias when presented to users through the alias.
See the <code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> element's
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html#label">label</a></code> attribute for more information.
</p></dd>

<dt><a name="nm">{@code android:name}</dt>
<dd>A unique name for the alias.  The name should resemble a fully
qualified class name.  But, unlike the name of the target activity, 
the alias name is arbitrary; it does not refer to an actual class.  
</p></dd>

<dt><a name="prmsn"></a>{@code android:permission}</dt>
<dd>The name of a permission that clients must have to launch the target activity 
or get it to do something via the alias.  If a caller of 
<code>{@link android.content.Context#startActivity startActivity()}</code> or
<code>{@link android.app.Activity#startActivityForResult startActivityForResult()}</code>
has not been granted the specified permission, the target activity will not be
activated. 

<p>This attribute supplants any permission set for the target activity itself.  If
it is not set, a permission is not needed to activate the target through the alias.
</p>

<p>
For more information on permissions, see the 
<a href="{@docRoot}guide/topics/manifest/manifest-intro.html#perms">Permissions</a> 
section in the introduction.
</p></dd>

<dt><a name="trgt"></a>{@code android:targetActivity}</dt>
<dd>The name of the activity that can be activated through the alias.
This name must match the {@code name} attribute of an 
<code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> element that precedes
the alias in the manifest.
</p></dd>
</dl></dd>

<!-- ##api level indication## -->
<dt>introduced in:</dt>
<dd>API Level 1</dd>

<dt>see also:</dt>
<dd><code><a href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code></dd>

</dl>