Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory. The manifest file presents essential information about your app to the Android system, information the system must have before it can run any of the app's code. Among other things, the manifest does the following:
- It names the Java package for the application. The package name serves as a unique identifier for the application.
- It describes the components of the application — the activities,
services, broadcast receivers, and content providers that the application is
composed of. It names the classes that implement each of the components and
publishes their capabilities (for example, which
Intentmessages they can handle). These declarations let the Android system know what the components are and under what conditions they can be launched.
- It determines which processes will host application components.
- It declares which permissions the application must have in order to access protected parts of the API and interact with other applications.
- It also declares the permissions that others are required to have in order to interact with the application's components.
- It lists the
Instrumentationclasses that provide profiling and other information as the application is running. These declarations are present in the manifest only while the application is being developed and tested; they're removed before the application is published.
- It declares the minimum level of the Android API that the application requires.
- It lists the libraries that the application must be linked against.
Structure of the Manifest File
The diagram below shows the general structure of the manifest file and every element that it can contain. Each element, along with all of its attributes, is documented in full in a separate file. To view detailed information about any element, click on the element name in the diagram, in the alphabetical list of elements that follows the diagram, or on any other mention of the element name.
<?xml version="1.0" encoding="utf-8"?> <manifest> <uses-permission /> <permission /> <permission-tree /> <permission-group /> <instrumentation /> <uses-sdk /> <uses-configuration /> <uses-feature /> <supports-screens /> <compatible-screens /> <supports-gl-texture /> <application> <activity> <intent-filter> <action /> <category /> <data /> </intent-filter> <meta-data /> </activity> <activity-alias> <intent-filter> . . . </intent-filter> <meta-data /> </activity-alias> <service> <intent-filter> . . . </intent-filter> <meta-data/> </service> <receiver> <intent-filter> . . . </intent-filter> <meta-data /> </receiver> <provider> <grant-uri-permission /> <meta-data /> <path-permission /> </provider> <uses-library /> </application> </manifest>
All the elements that can appear in the manifest file are listed below in alphabetical order. These are the only legal elements; you cannot add your own elements or attributes.
Some conventions and rules apply generally to all elements and attributes in the manifest:
- Only the
<application>elements are required, they each must be present and can occur only once. Most of the others can occur many times or not at all — although at least some of them must be present for the manifest to accomplish anything meaningful.
If an element contains anything at all, it contains other elements. All values are set through attributes, not as character data within an element.
Elements at the same level are generally not ordered. For example,
<service>elements can be intermixed in any sequence. There are two key exceptions to this rule, however:
- In a formal sense, all attributes are optional. However, there are some
that must be specified for an element to accomplish its purpose. Use the
documentation as a guide. For truly optional attributes, it mentions a default
value or states what happens in the absence of a specification.
Except for some attributes of the root
<manifest>element, all attribute names begin with an
android:prefix — for example,
android:alwaysRetainTaskState. Because the prefix is universal, the documentation generally omits it when referring to attributes by name.
- Declaring class names
- Many elements correspond to Java objects, including elements for the
application itself (the
<application>element) and its principal components — activities (
<activity>), services (
<service>), broadcast receivers (
<receiver>), and content providers (
If you define a subclass, as you almost always would for the component classes (
ContentProvider), the subclass is declared through a
nameattribute. The name must include the full package designation. For example, an
Servicesubclass might be declared as follows:
<manifest . . . > <application . . . > <service android:name="com.example.project.SecretService" . . . > . . . </service> . . . </application> </manifest>
However, as a shorthand, if the first character of the string is a period, the string is appended to the application's package name (as specified by the
packageattribute). The following assignment is the same as the one above:
<manifest package="com.example.project" . . . > <application . . . > <service android:name=".SecretService" . . . > . . . </service> . . . </application> </manifest>
When starting a component, Android creates an instance of the named subclass. If a subclass isn't specified, it creates an instance of the base class.
- Multiple values
- If more than one value can be specified, the element is almost always
repeated, rather than listing multiple values within a single element.
For example, an intent filter can list several actions:
<intent-filter . . . > <action android:name="android.intent.action.EDIT" /> <action android:name="android.intent.action.INSERT" /> <action android:name="android.intent.action.DELETE" /> . . . </intent-filter>
- Resource values
- Some attributes have values that can be displayed to users — for
example, a label and an icon for an activity. The values of these attributes
should be localized and therefore set from a resource or theme. Resource
values are expressed in the following format,
where the package name can be omitted if the resource is in the same package as the application, type is a type of resource — such as "string" or "drawable" — and name is the name that identifies the specific resource. For example:
<activity android:icon="@drawable/smallPic" . . . >
Values from a theme are expressed in a similar manner, but with an initial '
?' rather than '
- String values
- Where an attribute value is a string, double backslashes ('
\\') must be used to escape characters — for example, '
\\n' for a newline or '
\\uxxxx' for a Unicode character.
The following sections describe how some Android features are reflected in the manifest file.
The core components of an application (its activities, services, and broadcast
receivers) are activated by intents. An intent is a
bundle of information (an
Intent object) describing a
desired action — including the data to be acted upon, the category of
component that should perform the action, and other pertinent instructions.
Android locates an appropriate component to respond to the intent, launches
a new instance of the component if one is needed, and passes it the
Components advertise their capabilities — the kinds of intents they can
respond to — through intent filters. Since the Android system
must learn which intents a component can handle before it launches the component,
intent filters are specified in the manifest as
elements. A component may have any number of filters, each one describing
a different capability.
An intent that explicitly names a target component will activate that component; the filter doesn't play a role. But an intent that doesn't specify a target by name can activate a component only if it can pass through one of the component's filters.
For information on how Intent objects are tested against intent filters, see a separate document, Intents and Intent Filters.
Icons and Labels
A number of elements have
label attributes for a
small icon and a text label that can be displayed to users. Some also have a
description attribute for longer explanatory text that can also be
shown on-screen. For example, the
element has all three of these attributes, so that when the user is asked whether
to grant the permission to an application that has requested it, an icon representing
the permission, the name of the permission, and a description of what it
entails can all be presented to the user.
In every case, the icon and label set in a containing element become the default
label settings for all of the container's subelements.
Thus, the icon and label set in the
element are the default icon and label for each of the application's components.
Similarly, the icon and label set for a component — for example, an
element — are the default settings for each of the component's
elements. If an
element sets a label, but an activity and its intent filter do not,
the application label is treated as the label for both the activity and
the intent filter.
The icon and label set for an intent filter are used to represent a component
whenever the component is presented to the user as fulfilling the function
advertised by the filter. For example, a filter with
android.intent.category.LAUNCHER" settings advertises an activity
as one that initiates an application — that is, as
one that should be displayed in the application launcher. The icon and label
set in the filter are therefore the ones displayed in the launcher.
A permission is a restriction limiting access to a part of the code or to data on the device. The limitation is imposed to protect critical data and code that could be misused to distort or damage the user experience.
Each permission is identified by a unique label. Often the label indicates the action that's restricted. For example, here are some permissions defined by Android:
A feature can be protected by at most one permission.
If an application needs access to a feature protected by a permission,
it must declare that it requires that permission with a
element in the manifest. Then, when the application is installed on
the device, the installer determines whether or not to grant the requested
permission by checking the authorities that signed the application's
certificates and, in some cases, asking the user.
If the permission is granted, the application is able to use the protected
features. If not, its attempts to access those features will simply fail
without any notification to the user.
An application can also protect its own components (activities, services,
broadcast receivers, and content providers) with permissions. It can employ
any of the permissions defined by Android (listed in
android.Manifest.permission) or declared
by other applications. Or it can define its own. A new permission is declared
element. For example, an activity could be protected as follows:
<manifest . . . > <permission android:name="com.example.project.DEBIT_ACCT" . . . /> <uses-permission android:name="com.example.project.DEBIT_ACCT" /> . . . <application . . .> <activity android:name="com.example.project.FreneticActivity" android:permission="com.example.project.DEBIT_ACCT" . . . > . . . </activity> </application> </manifest>
Note that, in this example, the
DEBIT_ACCT permission is not only
declared with the
element, its use is also requested with the
element. Its use must be requested in order for other components of the
application to launch the protected activity, even though the protection
is imposed by the application itself.
If, in the same example, the
permission attribute was set to a
permission declared elsewhere
android.permission.CALL_EMERGENCY_NUMBERS, it would not
have been necessary to declare it again with a
element. However, it would still have been necessary to request its use with
element declares a namespace for a group of permissions that will be defined in
defines a label for a set of permissions (both those declared in the manifest with
elements and those declared elsewhere). It affects only how the permissions are
grouped when presented to the user. The
element does not specify which permissions belong to the group;
it just gives the group a name. A permission is placed in the group
by assigning the group name to the
Every application is linked against the default Android library, which includes the basic packages for building applications (with common classes such as Activity, Service, Intent, View, Button, Application, ContentProvider, and so on).
However, some packages reside in their own libraries. If your application
uses code from any of these packages, it must explicitly asked to be linked
against them. The manifest must contain a separate
element to name each of the libraries. (The library name can be found in the
documentation for the package.)