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am 64d14b5c: am 37826fa9: am 4e73847a: am 5cdadb48: initial shuffle of the API guide nav to add introduction * revise to the Compatibility doc, put it in Intro * put Permissions in Intro * put App Fundamentals in Intro * move Manifest docs to the top of side nav tree

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* commit '64d14b5cd9c548b313da1a9b211c3ea02deb753d':
  initial shuffle of the API guide nav to add introduction * revise to the Compatibility doc, put it in Intro * put Permissions in Intro * put App Fundamentals in Intro * move Manifest docs to the top of side nav tree * move App Resources above UI Will perform another fix to the Best Practices section later to deprecate some docs there and point to Training instead
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@@ -4,24 +4,9 @@ page.title=Application Fundamentals
<div id="qv-wrapper">
<div id="qv">
<h2>Quickview</h2>
<ul>
<li>Android applications are composed of one or more application components (activities,
services, content providers, and broadcast receivers)</li>
<li>Each component performs a different role in the overall application behavior, and each
one can be activated individually (even by other applications)</li>
<li>The manifest file must declare all components in the application and should also declare
all application requirements, such as the minimum version of Android required and any hardware
configurations required</li>
<li>Non-code application resources (images, strings, layout files, etc.) should include
alternatives for different device configurations (such as different strings for different
languages and different layouts for different screen sizes)</li>
</ul>
<h2>In this document</h2>
<ol>
<li><a href="#Components">Application Components</a>
<li><a href="#Components">App Components</a>
<ol>
<li><a href="#ActivatingComponents">Activating components</a></li>
</ol>
@@ -29,98 +14,91 @@ languages and different layouts for different screen sizes)</li>
<li><a href="#Manifest">The Manifest File</a>
<ol>
<li><a href="#DeclaringComponents">Declaring components</a></li>
<li><a href="#DeclaringRequirements">Declaring application requirements</a></li>
<li><a href="#DeclaringRequirements">Declaring app requirements</a></li>
</ol>
</li>
<li><a href="#Resources">Application Resources</a></li>
<li><a href="#Resources">App Resources</a></li>
</ol>
</div>
</div>
<p>Android applications are written in the Java programming language. The Android SDK tools compile
the code&mdash;along with any data and resource files&mdash;into an <i>Android package</i>, an
archive file with an {@code .apk} suffix. All the code in a single {@code .apk} file is considered
to be one application and is the file that Android-powered devices use to install the
application.</p>
<p>Android apps are written in the Java programming language. The Android SDK tools compile
your code&mdash;along with any data and resource files&mdash;into an APK: an <i>Android package</i>,
which is an archive file with an {@code .apk} suffix. One APK file contains all the contents
of an Android app and is the file that Android-powered devices use to install the app.</p>
<p>Once installed on a device, each Android application lives in its own security sandbox: </p>
<p>Once installed on a device, each Android app lives in its own security sandbox: </p>
<ul>
<li>The Android operating system is a multi-user Linux system in which each application is a
<li>The Android operating system is a multi-user Linux system in which each app is a
different user.</li>
<li>By default, the system assigns each application a unique Linux user ID (the ID is used only by
the system and is unknown to the application). The system sets permissions for all the files in an
application so that only the user ID assigned to that application can access them. </li>
<li>By default, the system assigns each app a unique Linux user ID (the ID is used only by
the system and is unknown to the app). The system sets permissions for all the files in an
app so that only the user ID assigned to that app can access them. </li>
<li>Each process has its own virtual machine (VM), so an application's code runs in isolation from
other applications.</li>
<li>Each process has its own virtual machine (VM), so an app's code runs in isolation from
other apps.</li>
<li>By default, every application runs in its own Linux process. Android starts the process when any
of the application's components need to be executed, then shuts down the process when it's no longer
needed or when the system must recover memory for other applications.</li>
<li>By default, every app runs in its own Linux process. Android starts the process when any
of the app's components need to be executed, then shuts down the process when it's no longer
needed or when the system must recover memory for other apps.</li>
</ul>
<p>In this way, the Android system implements the <em>principle of least privilege</em>. That is,
each application, by default, has access only to the components that it requires to do its work and
no more. This creates a very secure environment in which an application cannot access parts of
each app, by default, has access only to the components that it requires to do its work and
no more. This creates a very secure environment in which an app cannot access parts of
the system for which it is not given permission.</p>
<p>However, there are ways for an application to share data with other applications and for an
application to access system services:</p>
<p>However, there are ways for an app to share data with other apps and for an
app to access system services:</p>
<ul>
<li>It's possible to arrange for two applications to share the same Linux user ID, in which case
they are able to access each other's files. To conserve system resources, applications with the
<li>It's possible to arrange for two apps to share the same Linux user ID, in which case
they are able to access each other's files. To conserve system resources, apps with the
same user ID can also arrange to run in the same Linux process and share the same VM (the
applications must also be signed with the same certificate).</li>
<li>An application can request permission to access device data such as the user's
apps must also be signed with the same certificate).</li>
<li>An app can request permission to access device data such as the user's
contacts, SMS messages, the mountable storage (SD card), camera, Bluetooth, and more. All
application permissions must be granted by the user at install time.</li>
app permissions must be granted by the user at install time.</li>
</ul>
<p>That covers the basics regarding how an Android application exists within the system. The rest of
<p>That covers the basics regarding how an Android app exists within the system. The rest of
this document introduces you to:</p>
<ul>
<li>The core framework components that define your application.</li>
<li>The core framework components that define your app.</li>
<li>The manifest file in which you declare components and required device features for your
application.</li>
<li>Resources that are separate from the application code and allow your application to
app.</li>
<li>Resources that are separate from the app code and allow your app to
gracefully optimize its behavior for a variety of device configurations.</li>
</ul>
<!--
<p class="note"><strong>Tip:</strong> If you're new to Android development, we suggest that you
follow the Beginner's Path link at the bottom of this page. For each document in the Application
Fundamentals, the Beginner's Path points you to the document we suggest you read next, in order
to get up to speed on the core Android concepts.</p>
-->
<h2 id="Components">Application Components</h2>
<h2 id="Components">App Components</h2>
<p>Application components are the essential building blocks of an Android application. Each
component is a different point through which the system can enter your application. Not all
<p>App components are the essential building blocks of an Android app. Each
component is a different point through which the system can enter your app. Not all
components are actual entry points for the user and some depend on each other, but each one exists
as its own entity and plays a specific role&mdash;each one is a unique building block that
helps define your application's overall behavior.</p>
helps define your app's overall behavior.</p>
<p>There are four different types of application components. Each type serves a distinct purpose
<p>There are four different types of app components. Each type serves a distinct purpose
and has a distinct lifecycle that defines how the component is created and destroyed.</p>
<p>Here are the four types of application components:</p>
<p>Here are the four types of app components:</p>
<dl>
<dt><b>Activities</b></dt>
<dd>An <i>activity</i> represents a single screen with a user interface. For example,
an email application might have one activity that shows a list of new
an email app might have one activity that shows a list of new
emails, another activity to compose an email, and another activity for reading emails. Although
the activities work together to form a cohesive user experience in the email application, each one
is independent of the others. As such, a different application can start any one of these
activities (if the email application allows it). For example, a camera application can start the
activity in the email application that composes new mail, in order for the user to share a picture.
the activities work together to form a cohesive user experience in the email app, each one
is independent of the others. As such, a different app can start any one of these
activities (if the email app allows it). For example, a camera app can start the
activity in the email app that composes new mail, in order for the user to share a picture.
<p>An activity is implemented as a subclass of {@link android.app.Activity} and you can learn more
about it in the <a href="{@docRoot}guide/components/activities.html">Activities</a>
@@ -133,7 +111,7 @@ developer guide.</p>
<dd>A <i>service</i> is a component that runs in the background to perform long-running
operations or to perform work for remote processes. A service
does not provide a user interface. For example, a service might play music in the background while
the user is in a different application, or it might fetch data over the network without
the user is in a different app, or it might fetch data over the network without
blocking user interaction with an activity. Another component, such as an activity, can start the
service and let it run or bind to it in order to interact with it.
@@ -145,21 +123,21 @@ guide.</p>
<dt><b>Content providers</b></dt>
<dd>A <i>content provider</i> manages a shared set of application data. You can store the data in
<dd>A <i>content provider</i> manages a shared set of app data. You can store the data in
the file system, an SQLite database, on the web, or any other persistent storage location your
application can access. Through the content provider, other applications can query or even modify
app can access. Through the content provider, other apps can query or even modify
the data (if the content provider allows it). For example, the Android system provides a content
provider that manages the user's contact information. As such, any application with the proper
provider that manages the user's contact information. As such, any app with the proper
permissions can query part of the content provider (such as {@link
android.provider.ContactsContract.Data}) to read and write information about a particular person.
<p>Content providers are also useful for reading and writing data that is private to your
application and not shared. For example, the <a
href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample application uses a
app and not shared. For example, the <a
href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample app uses a
content provider to save notes.</p>
<p>A content provider is implemented as a subclass of {@link android.content.ContentProvider}
and must implement a standard set of APIs that enable other applications to perform
and must implement a standard set of APIs that enable other apps to perform
transactions. For more information, see the <a
href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a> developer
guide.</p>
@@ -171,7 +149,7 @@ guide.</p>
<dd>A <i>broadcast receiver</i> is a component that responds to system-wide broadcast
announcements. Many broadcasts originate from the system&mdash;for example, a broadcast announcing
that the screen has turned off, the battery is low, or a picture was captured.
Applications can also initiate broadcasts&mdash;for example, to let other applications know that
Apps can also initiate broadcasts&mdash;for example, to let other apps know that
some data has been downloaded to the device and is available for them to use. Although broadcast
receivers don't display a user interface, they may <a
href="{@docRoot}guide/topics/ui/notifiers/notifications.html">create a status bar notification</a>
@@ -188,26 +166,26 @@ see the {@link android.content.BroadcastReceiver} class.</p>
<p>A unique aspect of the Android system design is that any application can start another
application’s component. For example, if you want the user to capture a
photo with the device camera, there's probably another application that does that and your
application can use it, instead of developing an activity to capture a photo yourself. You don't
need to incorporate or even link to the code from the camera application.
Instead, you can simply start the activity in the camera application that captures a
photo. When complete, the photo is even returned to your application so you can use it. To the user,
it seems as if the camera is actually a part of your application.</p>
<p>A unique aspect of the Android system design is that any app can start another
app’s component. For example, if you want the user to capture a
photo with the device camera, there's probably another app that does that and your
app can use it, instead of developing an activity to capture a photo yourself. You don't
need to incorporate or even link to the code from the camera app.
Instead, you can simply start the activity in the camera app that captures a
photo. When complete, the photo is even returned to your app so you can use it. To the user,
it seems as if the camera is actually a part of your app.</p>
<p>When the system starts a component, it starts the process for that application (if it's not
<p>When the system starts a component, it starts the process for that app (if it's not
already running) and instantiates the classes needed for the component. For example, if your
application starts the activity in the camera application that captures a photo, that activity
runs in the process that belongs to the camera application, not in your application's process.
Therefore, unlike applications on most other systems, Android applications don't have a single entry
app starts the activity in the camera app that captures a photo, that activity
runs in the process that belongs to the camera app, not in your app's process.
Therefore, unlike apps on most other systems, Android apps don't have a single entry
point (there's no {@code main()} function, for example).</p>
<p>Because the system runs each application in a separate process with file permissions that
restrict access to other applications, your application cannot directly activate a component from
another application. The Android system, however, can. So, to activate a component in
another application, you must deliver a message to the system that specifies your <em>intent</em> to
<p>Because the system runs each app in a separate process with file permissions that
restrict access to other apps, your app cannot directly activate a component from
another app. The Android system, however, can. So, to activate a component in
another app, you must deliver a message to the system that specifies your <em>intent</em> to
start a particular component. The system then activates the component for you.</p>
@@ -217,7 +195,7 @@ start a particular component. The system then activates the component for you.</
broadcast receivers&mdash;are activated by an asynchronous message called an <em>intent</em>.
Intents bind individual components to each other at runtime (you can think of them
as the messengers that request an action from other components), whether the component belongs
to your application or another.</p>
to your app or another.</p>
<p>An intent is created with an {@link android.content.Intent} object, which defines a message to
activate either a specific component or a specific <em>type</em> of component&mdash;an intent
@@ -273,21 +251,21 @@ href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers
<h2 id="Manifest">The Manifest File</h2>
<p>Before the Android system can start an application component, the system must know that the
component exists by reading the application's {@code AndroidManifest.xml} file (the "manifest"
file). Your application must declare all its components in this file, which must be at the root of
the application project directory.</p>
<p>Before the Android system can start an app component, the system must know that the
component exists by reading the app's {@code AndroidManifest.xml} file (the "manifest"
file). Your app must declare all its components in this file, which must be at the root of
the app project directory.</p>
<p>The manifest does a number of things in addition to declaring the application's components,
<p>The manifest does a number of things in addition to declaring the app's components,
such as:</p>
<ul>
<li>Identify any user permissions the application requires, such as Internet access or
<li>Identify any user permissions the app requires, such as Internet access or
read-access to the user's contacts.</li>
<li>Declare the minimum <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a>
required by the application, based on which APIs the application uses.</li>
<li>Declare hardware and software features used or required by the application, such as a camera,
required by the app, based on which APIs the app uses.</li>
<li>Declare hardware and software features used or required by the app, such as a camera,
bluetooth services, or a multitouch screen.</li>
<li>API libraries the application needs to be linked against (other than the Android framework
<li>API libraries the app needs to be linked against (other than the Android framework
APIs), such as the <a
href="http://code.google.com/android/add-ons/google-apis/maps-overview.html">Google Maps
library</a>.</li>
@@ -297,7 +275,7 @@ library</a>.</li>
<h3 id="DeclaringComponents">Declaring components</h3>
<p>The primary task of the manifest is to inform the system about the application's components. For
<p>The primary task of the manifest is to inform the system about the app's components. For
example, a manifest file can declare an activity as follows: </p>
<pre>
@@ -314,7 +292,7 @@ example, a manifest file can declare an activity as follows: </p>
<p>In the <code><a
href="{@docRoot}guide/topics/manifest/application-element.html">&lt;application&gt;</a></code>
element, the {@code android:icon} attribute points to resources for an icon that identifies the
application.</p>
app.</p>
<p>In the <code><a
href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> element,
@@ -322,7 +300,7 @@ the {@code android:name} attribute specifies the fully qualified class name of t
android.app.Activity} subclass and the {@code android:label} attributes specifies a string
to use as the user-visible label for the activity.</p>
<p>You must declare all application components this way:</p>
<p>You must declare all app components this way:</p>
<ul>
<li><code><a
href="{@docRoot}guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></code> elements
@@ -345,7 +323,7 @@ receivers can be either declared in the manifest or created dynamically in code
{@link android.content.BroadcastReceiver} objects) and registered with the system by calling
{@link android.content.Context#registerReceiver registerReceiver()}.</p>
<p>For more about how to structure the manifest file for your application, see <a
<p>For more about how to structure the manifest file for your app, see <a
href="{@docRoot}guide/topics/manifest/manifest-intro.html">The AndroidManifest.xml File</a>
documentation. </p>
@@ -356,28 +334,43 @@ documentation. </p>
<p>As discussed above, in <a href="#ActivatingComponents">Activating Components</a>, you can use an
{@link android.content.Intent} to start activities, services, and broadcast receivers. You can do so
by explicitly naming the target component (using the component class name) in the intent. However,
the real power of intents lies in the concept of intent actions. With intent actions, you simply
describe the type of action you want to perform (and optionally, the data upon which you’d like to
the real power of intents lies in the concept of <em>implicit intents</em>. An implicit intent
simply describe the type of action to perform (and optionally, the data upon which you’d like to
perform the action) and allow the system to find a component on the device that can perform the
action and start it. If there are multiple components that can perform the action described by the
intent, then the user selects which one to use.</p>
<p>The way the system identifies the components that can respond to an intent is by comparing the
intent received to the <i>intent filters</i> provided in the manifest file of other applications on
intent received to the <i>intent filters</i> provided in the manifest file of other apps on
the device.</p>
<p>When you declare a component in your application's manifest, you can optionally include
intent filters that declare the capabilities of the component so it can respond to intents
from other applications. You can declare an intent filter for your component by
<p>When you declare an activity in your app's manifest, you can optionally include
intent filters that declare the capabilities of the activity so it can respond to intents
from other apps. You can declare an intent filter for your component by
adding an <a href="{@docRoot}guide/topics/manifest/intent-filter-element.html">{@code
&lt;intent-filter&gt;}</a> element as a child of the component's declaration element.</p>
<p>For example, an email application with an activity for composing a new email might declare an
intent filter in its manifest entry to respond to "send" intents (in order to send email). An
activity in your application can then create an intent with the “send” action ({@link
android.content.Intent#ACTION_SEND}), which the system matches to the email application’s “send”
activity and launches it when you invoke the intent with {@link android.app.Activity#startActivity
startActivity()}.</p>
<p>For example, if you've built an email app with an activity for composing a new email, you can
declare an intent filter to respond to "send" intents (in order to send a new email) like this:</p>
<pre>
&lt;manifest ... >
...
&lt;application ... &gt;
&lt;activity android:name="com.example.project.ComposeEmailActivity">
&lt;intent-filter>
&lt;action android:name="android.intent.action.SEND" />
&lt;data android:type="*/*" />
&lt;category android:name="android.intent.category.DEFAULT" />
&lt;/intent-filter>
&lt;/activity>
&lt;/application&gt;
&lt;/manifest>
</pre>
<p>Then, if another app creates an intent with the {@link
android.content.Intent#ACTION_SEND} action and pass it to {@link android.app.Activity#startActivity
startActivity()}, the system may start your activity so the user can draft and send an
email.</p>
<p>For more about creating intent filters, see the <a
href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a> document.
@@ -385,102 +378,57 @@ href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filter
<h3 id="DeclaringRequirements">Declaring application requirements</h3>
<h3 id="DeclaringRequirements">Declaring app requirements</h3>
<p>There are a variety of devices powered by Android and not all of them provide the
same features and capabilities. In order to prevent your application from being installed on devices
that lack features needed by your application, it's important that you clearly define a profile for
the types of devices your application supports by declaring device and software requirements in your
same features and capabilities. In order to prevent your app from being installed on devices
that lack features needed by your app, it's important that you clearly define a profile for
the types of devices your app supports by declaring device and software requirements in your
manifest file. Most of these declarations are informational only and the system does not read
them, but external services such as Google Play do read them in order to provide filtering
for users when they search for applications from their device.</p>
for users when they search for apps from their device.</p>
<p>For example, if your application requires a camera and uses APIs introduced in Android 2.1 (<a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> 7), you should declare these as
requirements in your manifest file. That way, devices that do <em>not</em> have a camera and have an
Android version <em>lower</em> than 2.1 cannot install your application from Google Play.</p>
<p>For example, if your app requires a camera and uses APIs introduced in Android 2.1 (<a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> 7),
you should declare these as requirements in your manifest file like this:</p>
<p>However, you can also declare that your application uses the camera, but does not
<em>require</em> it. In that case, your application must perform a check at runtime to determine
if the device has a camera and disable any features that use the camera if one is not available.</p>
<pre>
&lt;manifest ... >
&lt;uses-feature android:name="android.hardware.camera.any"
android:required="true" />
&lt;uses-sdk android:minSdkVersion="7" android:targetSdkVersion="19" />
...
&lt;/manifest>
</pre>
<p>Here are some of the important device characteristics that you should consider as you design and
develop your application:</p>
<p>Now, devices that do <em>not</em> have a camera and have an
Android version <em>lower</em> than 2.1 cannot install your app from Google Play.</p>
<dl>
<dt>Screen size and density</dt>
<dd>In order to categorize devices by their screen type, Android defines two characteristics for
each device: screen size (the physical dimensions of the screen) and screen density (the physical
density of the pixels on the screen, or dpi&mdash;dots per inch). To simplify all the different
types of screen configurations, the Android system generalizes them into select groups that make
them easier to target.
<p>The screen sizes are: small, normal, large, and extra large.<br/>
The screen densities are: low density, medium density, high density, and extra high density.</p>
<p>However, you can also declare that your app uses the camera, but does not
<em>require</em> it. In that case, your app must set the <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html#required">{@code required}</a>
attribute to {@code "false"} and check at runtime whether
the device has a camera and disable any camera features as appropriate.</p>
<p>By default, your application is compatible with all screen sizes and densities,
because the Android system makes the appropriate adjustments to your UI layout and image
resources. However, you should create specialized layouts for certain screen sizes and provide
specialized images for certain densities, using alternative layout resources, and by declaring in
your manifest exactly which screen sizes your application supports with the <a
href="{@docRoot}guide/topics/manifest/supports-screens-element.html">{@code
&lt;supports-screens&gt;}</a> element.</p>
<p>For more information, see the <a
href="{@docRoot}guide/practices/screens_support.html">Supporting Multiple Screens</a>
document.</p></dd>
<dt>Input configurations</dt>
<dd>Many devices provide a different type of user input mechanism, such as a hardware keyboard, a
trackball, or a five-way navigation pad. If your application requires a particular kind of input
hardware, then you should declare it in your manifest with the <a
href="{@docRoot}guide/topics/manifest/uses-configuration-element.html">{@code
&lt;uses-configuration&gt;}</a> element. However, it is rare that an application should require
a certain input configuration.</dd>
<dt>Device features</dt>
<dd>There are many hardware and software features that may or may not exist on a given
Android-powered device, such as a camera, a light sensor, bluetooth, a certain
version of OpenGL, or the fidelity of the touchscreen. You should never assume that a certain
feature is available on all Android-powered devices (other than the availability of the standard
Android library), so you should declare any features used by your application with the <a
href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code &lt;uses-feature&gt;}</a>
element.</dd>
<dt>Platform Version</dt>
<dd>Different Android-powered devices often run different versions of the Android platform,
such as Android 1.6 or Android 2.3. Each successive version often includes additional APIs not
available in the previous version. In order to indicate which set of APIs are available, each
platform version specifies an <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API Level</a> (for example, Android 1.0 is API Level
1 and Android 2.3 is API Level 9). If you use any APIs that were added to the platform after
version 1.0, you should declare the minimum API Level in which those APIs were introduced using the
<a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code &lt;uses-sdk&gt;}</a>
element.</dd>
</dl>
<p>It's important that you declare all such requirements for your application, because, when you
distribute your application on Google Play, the store uses these declarations to filter which
applications are available on each device. As such, your application should be available only to
devices that meet all your application requirements.</p>
<p>For more information about how Google Play filters applications based on these (and other)
requirements, see the <a href="{@docRoot}google/play/filters.html">Filters on Google Play</a>
<p>More information about how you can manage your app's compatibility with different devices
is provided in the <a href="{@docRoot}guide/practices/compatibility.html">Device Compatibility</a>
document.</p>
<h2 id="Resources">Application Resources</h2>
<h2 id="Resources">App Resources</h2>
<p>An Android application is composed of more than just code&mdash;it requires resources that are
<p>An Android app is composed of more than just code&mdash;it requires resources that are
separate from the source code, such as images, audio files, and anything relating to the visual
presentation of the application. For example, you should define animations, menus, styles, colors,
and the layout of activity user interfaces with XML files. Using application resources makes it easy
to update various characteristics of your application without modifying code and&mdash;by providing
sets of alternative resources&mdash;enables you to optimize your application for a variety of
presentation of the app. For example, you should define animations, menus, styles, colors,
and the layout of activity user interfaces with XML files. Using app resources makes it easy
to update various characteristics of your app without modifying code and&mdash;by providing
sets of alternative resources&mdash;enables you to optimize your app for a variety of
device configurations (such as different languages and screen sizes).</p>
<p>For every resource that you include in your Android project, the SDK build tools define a unique
integer ID, which you can use to reference the resource from your application code or from
other resources defined in XML. For example, if your application contains an image file named {@code
integer ID, which you can use to reference the resource from your app code or from
other resources defined in XML. For example, if your app contains an image file named {@code
logo.png} (saved in the {@code res/drawable/} directory), the SDK tools generate a resource ID
named {@code R.drawable.logo}, which you can use to reference the image and insert it in your
user interface.</p>
@@ -504,15 +452,45 @@ depending on the orientation, you can define two different layouts and apply the
qualifier to each layout's directory name. Then, the system automatically applies the appropriate
layout depending on the current device orientation.</p>
<p>For more about the different kinds of resources you can include in your application and how
to create alternative resources for various device configurations, see the <a
href="{@docRoot}guide/topics/resources/index.html">Application Resources</a> developer guide.</p>
<p>For more about the different kinds of resources you can include in your application and how to
create alternative resources for different device configurations, read <a href=
"{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a>.</p>
<!--
<h2>Beginner's Path</h2>
<p>For a close look at implementing activities&mdash;the components your users use to
interact with your application&mdash;continue with the <b><a
href="{@docRoot}guide/components/activities.html">Activities</a></b> document.</p>
-->
<div class="next-docs">
<div class="col-6">
<h2 class="norule">Continue reading about:</h2>
<dl>
<dt><a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a>
</dt>
<dd>Information about how to use the {@link android.content.Intent} APIs to
activate app components, such as activities and services, and how to make your app components
available for use by other apps.</dd>
<dt><a href="{@docRoot}guide/components/activities.html">Activities</a></dt>
<dd>Information about how to create an instance of the {@link android.app.Activity} class,
which provides a distinct screen in your application with a user interface.</dd>
<dt><a
href="{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a></dt>
<dd>Information about how Android apps are structured to separate app resources from the
app code, including how you can provide alternative resources for specific device
configurations.
</dd>
</dl>
</div>
<div class="col-6">
<h2 class="norule">You might also be interested in:</h2>
<dl>
<dt><a href="{@docRoot}guide/practices/compatibility.html"
>Device Compatibility</a></dt>
<dd>Information about Android works on different types of devices and an introduction
to how you can optimize your app for each device or restrict your app's availability
to different devices.</dd>
<dt><a href="{@docRoot}guide/topics/security/permissions.html"
>System Permissions</a></dt>
<dd>Information about how Android restricts app access to certain APIs with a permission
system that requires the user's consent for your app to use those APIs.</dd>
</dl>
</div>
</div>

2
docs/html/guide/components/index.jd
View File

@@ -1,6 +1,6 @@
page.title=App Components
page.landing=true
page.landing.intro=Android's application framework lets you create extremely rich and innovative apps using a set of reusable components. This section explains how Android apps work and how you use components to build them.
page.landing.intro=Android's application framework lets you create rich and innovative apps using a set of reusable components. This section explains how you can build the components that define the building blocks of your app and how to connect them together using intents.
page.landing.image=images/develop/app_components.png
@jd:body

273
docs/html/guide/guide_toc.cs
View File

@@ -6,16 +6,40 @@
localized titles are added in the language order specified below.
?>
<ul id="nav">
<!-- Walkthrough for Developers -- quick overview of what it's like to develop on Android -->
<!--<li style="color:red">Overview</li> -->
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/index.html">
<span class="en">Introduction</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/components/fundamentals.html">
<span class="en">App Fundamentals</span></a>
</li>
<li><a href="<?cs var:toroot ?>guide/practices/compatibility.html">
<span class="en">Device Compatibility</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/security/permissions.html">
<span class="en">System Permissions</span>
</a>
</li>
</ul>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/components/index.html">
<span class="en">App Components</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/components/fundamentals.html">
<span class="en">App Fundamentals</span></a>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/components/intents-filters.html">
<span class="en">Intents and Intent Filters</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/components/intents-common.html">
<span class="en">Common Intents</span>
</a></li>
</ul>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/components/activities.html">
@@ -68,24 +92,6 @@
</a></li>
</ul>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/components/intents-filters.html">
<span class="en">Intents and Intent Filters</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/components/intents-common.html">
<span class="en">Common Intents</span>
</a></li>
</ul>
</li>
<li><a href="<?cs var:toroot ?>guide/components/processes-and-threads.html">
<span class="en">Processes and Threads</span>
</a>
</li>
<li><a href="<?cs var:toroot ?>guide/topics/security/permissions.html">
<span class="en">Permissions</span>
</a>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/appwidgets/index.html">
<span class="en">App Widgets</span>
@@ -96,43 +102,90 @@
</a></li>
</ul>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/manifest/manifest-intro.html">
<span class="en">Android Manifest</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/action-element.html">&lt;action&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/activity-alias-element.html">&lt;activity-alias&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/application-element.html">&lt;application&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/category-element.html">&lt;category&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/compatible-screens-element.html">&lt;compatible-screens&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/data-element.html">&lt;data&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/grant-uri-permission-element.html">&lt;grant-uri-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/instrumentation-element.html">&lt;instrumentation&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/intent-filter-element.html">&lt;intent-filter&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/manifest-element.html">&lt;manifest&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/meta-data-element.html">&lt;meta-data&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/path-permission-element.html">&lt;path-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-element.html">&lt;permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-group-element.html">&lt;permission-group&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-tree-element.html">&lt;permission-tree&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/receiver-element.html">&lt;receiver&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/service-element.html">&lt;service&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/supports-gl-texture-element.html">&lt;supports-gl-texture&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/supports-screens-element.html">&lt;supports-screens&gt;</a></li><!-- ##api level 4## -->
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-configuration-element.html">&lt;uses-configuration&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-feature-element.html">&lt;uses-feature&gt;</a></li> <!-- ##api level 4## -->
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-library-element.html">&lt;uses-library&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-sdk-element.html">&lt;uses-sdk&gt;</a></li>
</ul>
</li><!-- end of the manifest file -->
<li><a href="<?cs var:toroot ?>guide/components/processes-and-threads.html">
<span class="en">Processes and Threads</span>
</a>
</li>
</ul>
</li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/resources/index.html">
<span class="en">App Resources</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/resources/overview.html">
<span class="en">Overview</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/providing-resources.html">
<span class="en">Providing Resources</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/accessing-resources.html">
<span class="en">Accessing Resources</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/runtime-changes.html">
<span class="en">Handling Runtime Changes</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/localization.html">
<span class="en">Localization</span>
</a></li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/resources/available-resources.html">
<span class="en">Resource Types</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/resources/animation-resource.html">Animation</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/color-list-resource.html">Color State List</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/drawable-resource.html">Drawable</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/layout-resource.html">Layout</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/menu-resource.html">Menu</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/string-resource.html">String</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/style-resource.html">Style</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/more-resources.html">More Types</a></li>
</ul>
</li><!-- end of resource types -->
</ul>
</li><!-- end of app resources -->
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/manifest/manifest-intro.html">
<span class="en">App Manifest</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/action-element.html">&lt;action&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/activity-element.html">&lt;activity&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/activity-alias-element.html">&lt;activity-alias&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/application-element.html">&lt;application&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/category-element.html">&lt;category&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/compatible-screens-element.html">&lt;compatible-screens&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/data-element.html">&lt;data&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/grant-uri-permission-element.html">&lt;grant-uri-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/instrumentation-element.html">&lt;instrumentation&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/intent-filter-element.html">&lt;intent-filter&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/manifest-element.html">&lt;manifest&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/meta-data-element.html">&lt;meta-data&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/path-permission-element.html">&lt;path-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-element.html">&lt;permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-group-element.html">&lt;permission-group&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/permission-tree-element.html">&lt;permission-tree&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/provider-element.html">&lt;provider&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/receiver-element.html">&lt;receiver&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/service-element.html">&lt;service&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/supports-gl-texture-element.html">&lt;supports-gl-texture&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/supports-screens-element.html">&lt;supports-screens&gt;</a></li><!-- ##api level 4## -->
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-configuration-element.html">&lt;uses-configuration&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-feature-element.html">&lt;uses-feature&gt;</a></li> <!-- ##api level 4## -->
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-library-element.html">&lt;uses-library&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/manifest/uses-sdk-element.html">&lt;uses-sdk&gt;</a></li>
</ul>
</li><!-- end of the manifest file -->
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/ui/index.html">
<span class="en">User Interface</span>
@@ -259,44 +312,6 @@
</ul>
</li><!-- end of User Interface -->
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/resources/index.html">
<span class="en">App Resources</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/resources/overview.html">
<span class="en">Overview</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/providing-resources.html">
<span class="en">Providing Resources</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/accessing-resources.html">
<span class="en">Accessing Resources</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/runtime-changes.html">
<span class="en">Handling Runtime Changes</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/localization.html">
<span class="en">Localization</span>
</a></li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/resources/available-resources.html">
<span class="en">Resource Types</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/topics/resources/animation-resource.html">Animation</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/color-list-resource.html">Color State List</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/drawable-resource.html">Drawable</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/layout-resource.html">Layout</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/menu-resource.html">Menu</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/string-resource.html">String</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/style-resource.html">Style</a></li>
<li><a href="<?cs var:toroot ?>guide/topics/resources/more-resources.html">More Types</a></li>
</ul>
</li><!-- end of resource types -->
</ul>
</li><!-- end of app resources -->
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/topics/graphics/index.html">
<span class="en">Animation and Graphics</span>
@@ -527,9 +542,6 @@
<span class="zh-tw" style="display:none">最佳實務</span>
</div></a>
<ul>
<li><a href="<?cs var:toroot ?>guide/practices/compatibility.html">
<span class="en">Compatibility</span>
</a></li>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/practices/screens_support.html">
<span class="en">Supporting Multiple Screens</span>
@@ -550,74 +562,7 @@
</ul>
</li>
<!-- this needs to move
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/index.html">
<span class="en">UI Guidelines</span>
</a></div>
<ul>
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design.html">
<span class="en">Icon Design</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_launcher.html">
<span class="en">Launcher Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_menu.html">
<span class="en">Menu Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_action_bar.html">
<span class="en">Action Bar Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_status_bar.html">
<span class="en">Status Bar Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_tab.html">
<span class="en">Tab Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_dialog.html">
<span class="en">Dialog Icons</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/icon_design_list.html">
<span class="en">List View Icons</span>
</a></li>
</ul>
</li>
<li><div><a href="<?cs var:toroot ?>guide/practices/ui_guidelines/widget_design.html">
<span class="en">App Widget Design</span>
</a></div>
</li>
</ul>
</li>
</ul> -->
<!-- Remove
<li class="nav-section">
<div class="nav-section-header"><a href="<?cs var:toroot ?>guide/appendix/index.html">
<span class="en">Appendix</span>
<span class="de" style="display:none">Anhang</span>
<span class="es" style="display:none">Apéndice</span>
<span class="fr" style="display:none">Annexes</span>
<span class="it" style="display:none">Appendice</span>
<span class="ja" style="display:none">付録</span>
<span class="zh-cn" style="display:none">附录</span>
<span class="zh-tw" style="display:none">附錄</span>
</a></div>
<ul>
<li><a href="<?cs var:toroot ?>guide/appendix/g-app-intents.html">
<span class="en">Intents List: Google Apps</span>
</a></li>
<li><a href="<?cs var:toroot ?>guide/appendix/glossary.html">
<span class="en">Glossary</span>
</a></li>
</ul>
</li>
</li>
-->
</ul>

75
docs/html/guide/index.jd Normal file
View File

@@ -0,0 +1,75 @@
page.title=Introduction to Android
@jd:body
<div class="sidebox" style="width:220px"><!-- width to match col-4 below -->
<p>To learn how apps work, start with
<a href="{@docRoot}guide/components/fundamentals.html">App Fundamentals</a>.</p>
<p>To begin coding right away, read <a
href="{@docRoot}training/basics/firstapp/index.html">Building Your First App</a>.</p>
</div>
<p>Android provides a rich application framework that allows you to build innovative apps and games
for mobile devices in a Java language environment. The documents listed in the left
navigation provide details about how to build apps using Android's various APIs.</p>
<p>If you're new to Android development, it's important that you understand
the following fundamental concepts about the Android app framework:</p>
<div class="landing-banner">
<div class="col-6">
<h4>Apps provide multiple entry points</h4>
<p>Android apps are built as a combination of distinct components that can be invoked
individually. For instance, an individual <em>activity</em> provides a single
screen for a user interface, and a <em>service</em> independently performs
work in the background.</p>
<p>From one component you can start another component using an <em>intent</em>. You can even start
a component in a different app, such an activity in a maps app to show an address. This model
provides multiple entry points for a single app and allows any app to behave as a user's "default"
for an action that other apps may invoke.</p>
<p><b>Learn more:</b></p>
<ul class="nolist">
<li><a href="{@docRoot}guide/components/fundamentals.html">App Fundamentals</a>
<li><a href="{@docRoot}guide/components/intents-filters.html">Intents and Intent Filters</a>
<li><a href="{@docRoot}guide/components/activities.html">Activities</a>
</ul>
</div>
<div class="col-6">
<h4>Apps adapt to different devices</h4>
<p>Android provides an adaptive app framework that allows you to provide unique resources
for different device configurations. For example, you can create different XML
layout files for different screen sizes and the system
determines which layout to apply based on the current device's screen size.</p>
<p>You can query the availability of device features at runtime if any app features require
specific hardware such as a camera. If necessary, you can also declare features your app requires
so app markets such as Google Play Store do not allow installation on devices that do not support
that feature.</p>
<p><b>Learn more:</b></p>
<ul class="nolist">
<li><a href="{@docRoot}guide/practices/compatibility.html">Device Compatibility</a>
<li><a href="{@docRoot}guide/topics/resources/overview.html">Resources Overview</a>
<li><a href="{@docRoot}guide/topics/ui/overview.html">User Interface Overview</a>
</ul>
</div>
</div><!-- end landing-banner -->

489
docs/html/guide/practices/compatibility.jd
View File

@@ -1,248 +1,333 @@
page.title=Android Compatibility
page.title=Device Compatibility
excludeFromSuggestions=true
@jd:body
<div id="qv-wrapper">
<div id="qv">
<h2>In this document</h2>
<ol>
<li><a href="#defined">What Does "Compatibility" Mean?</a></li>
<li><a href="#how">Controlling Your App's Availability to Devices</a>
<ol>
<li><a href="#Features">Device features</a></li>
<li><a href="#Versions">Platform version</a></li>
<li><a href="#Screens">Screen configuration</a></li>
</ol>
</li>
<li><a href="#filtering">Controlling Your App's Availability for Business Reasons</a></li>
</ol>
<h2>See also</h2>
<ol>
<li><a
href="{@docRoot}google/play/filters.html">Filtering on Google Play</a></li>
<li><a
href="{@docRoot}guide/topics/resources/providing-resources.html#AlternativeResources">Providing Alternative Resources</a></li>
<li><a
href="{@docRoot}guide/practices/screens_support.html">Supporting Multiple Screens</a></li>
<li style="margin-top:3px;"><code><a
href="{@docRoot}guide/topics/manifest/supports-screens-element.html">&lt;supports-screens&gt;</a></code></li>
<li><code><a
href="{@docRoot}guide/topics/manifest/uses-configuration-element.html">&lt;uses-configuration&gt;</a></code></li>
<li><code><a
href="{@docRoot}guide/topics/manifest/uses-feature-element.html">&lt;uses-feature&gt;</a></code></li>
<li><code><a
href="{@docRoot}guide/topics/manifest/uses-library-element.html">&lt;uses-library&gt;</a></code></li>
<li><code><a
href="{@docRoot}guide/topics/manifest/uses-permission-element.html">&lt;uses-permission&gt;</a></code></li>
<li><code><a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">&lt;uses-sdk&gt;</code></a></li>
href="{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a></li>
<li><a href="http://source.android.com/compatibility/index.html" class="external-link">
Android Compatibility</a></li>
</ol>
</div> </div>
<p>Android is designed to run on many different types of devices. For
developers, the range and number of devices means a huge potential audience: the
more devices that run Android apps, the more users who can access your app. In
exchange, however, it also means that your apps will have to cope with that same
variety of hardware.</p>
<p>Android is designed to run on many different types of devices, from phones
to tablets and televisions. As a developer,
the range of devices provides a huge potential audience for your app. In order for your app
to be successful on all these devices, it should tolerate some feature variability
and provide a flexible user interface that adapts to different screen
configurations.</p>
<p>Fortunately, Android has built-in tools and support that make it easy for
your apps to do that, while at the same time letting you maintain control of
what types of devices your app is available to. With a bit of forethought and
some minor changes in your app's manifest file, you can ensure that users
whose devices can’t run your app will never see it on Google Play, and
will not get in trouble by downloading it. This page explains how you can
control which devices have access to your apps, and how to prepare your apps to
make sure they reach the right audience.</p>
<p>To facilitate your effort toward that goal, Android provides a dynamic app framework in which
you can provide configuration-specific <a href="{@docRoot}guide/topics/resources/overview.html"
>app resources</a> in static files (such as different XML layouts
for different screen sizes). Android then loads the appropriate resources based on
the current device configuration. So with some forethought to your app design and some additional
app resources, you can publish a single application package (APK) that provides an optimized user
experience on a variety of devices.
<p>If necessary, however, you can specify your app's feature requirements and control
which types of devices can install your app from Google Play Store. This page explains how you can
control which devices have access to your apps, and how to prepare your apps to make sure they
reach the right audience. For more information about how you can make your app adapt
to different devices, read <a href="{@docRoot}training/basics/supporting-devices/index.html"
>Supporting Different Devices</a>.</p>
<h3 id="defined">What does “compatibility” mean?</h3>
<p>A device is “Android compatible” if it can correctly run apps written for the
<h2 id="defined">What Does "Compatibility" Mean?</h2>
<p>As you read more about Android development, you'll probably encounter the term "compatibility"
in various situations. There are two types of compatibility: <em>device compatibility</em>
and <em>app compatibility</em>.
<p>Because Android is an open source project, any hardware manufacturer can build a device
that runs the Android operating system. Yet, a <b>device is "Android compatible"</b> only if
it can correctly run apps written for the
<em>Android execution environment</em>. The exact details of the Android execution
environment</em> are defined by the Android Compatibility Definition Document,
but the single most important characteristic of a compatible device is the
ability to install and correctly run an Android <code>.apk</code> file.</p>
environment are defined by the <a href="http://source.android.com/compatibility/overview.html"
class="external-link">Android compatibility program</a> and each device must pass the Compatibility
Test Suite (CTS) in order to be considered compatible.</p>
<p>There is exactly one Android API for each <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API level</a>, and it’s the same
API no matter what kind of device it’s installed on. No parts of the API are
optional, and you never have to worry about parts of the API missing on some
devices. Every compatible Android device your app will land on will include
every class and every API for that API level.</p>
<p>As an app developer, you don't need to worry about whether a device is Android compatible, because
only devices that are Android compatible include Google Play Store. So you can rest assured that
users who install your app from Google Play Store are using an Android compatible device.</p>
<p>Of course, some APIs won’t work correctly if a particular device lacks the
corresponding hardware or feature. But that’s not a problem: we also designed
Android to prevent apps from being visible to devices which don’t have features
the apps require. We’ve built support for this right into the SDK tools, and
it’s part of the Android platform itself, as well as part of Google Play.</p>
<p>As a developer, you have complete control of how and where your apps are
available. Android provides tools as a first-class part of the platform that let
you manage this. You control the availability of your apps, so that they reach
only the devices capable of running them.</p>
<p>However, you do need to consider whether your <b>app is compatible</b> with each potential
device configuration. Because Android runs on a wide range of device configurations, some features are not
available on all devices. For example, some devices may not include a
compass sensor. If your app's core functionality requires the use
of a compass sensor, then your app is compatible only with devices that
include a compass sensor.</p>
<h3 id="how">How does it work?</h3>
<p>You manage your app’s availability through a simple three-step process:</p>
<ol>
<li>You state the features your app requires by declaring <a
href="{@docRoot}guide/topics/manifest/uses-feature-element.html"><code>&lt;uses-feature&gt;</code></a>
elements its manifest file.</li>
<li>Devices are required to declare the features they include to Google
Play.</li>
<li>Google Play uses your app’s stated requirements to filter it from devices
that don’t meet those requirements.</li>
</ol>
<p>This way, users never even see apps that won’t work properly on their
devices. As long as you accurately describe your app’s requirements, you don’t
need to worry about users blaming you for compatibility problems.</p>
<h2 id="how">Controlling Your App's Availability to Devices</h2>
<p>If you’re familiar with web development, you may recognize this model as
“capability detection”. Web developers typically prefer this approach to
“browser detection”, because it’s very difficult to keep up as new browsers and
new versions of current browsers are released. By checking for support for
specific required capabilities instead of the current browser, web developers
get better fine-grained control. That’s the same approach Android uses: since
it’s impossible to keep up with all the Android devices being released, you
instead use the fine-grained controls Android provides.</p>
<p>Android supports a variety of features your app can leverage through platform APIs. Some
features are hardware-based (such as a compass sensor), some are software-based (such as app
widgets), and some are dependent on the platform version. Not every device supports every feature,
so you may need to control your app's availability to devices based on your app's required
features.</p>
<h3>Filtering for technical reasons</h3>
<div class="sidebox-wrapper">
<img id="rule" src="{@docRoot}assets/images/grad-rule-qv.png">
<div id="qv-sub-rule">
<img src="{@docRoot}assets/images/icon_play.png" style="float:left;margin:0;padding:0;">
<p style="color:#669999;">Filtering on Google Play</p>
<p>To achieve the largest user-base possible for your app, you should strive to support as many
device configurations as possible using a single APK. In most situations, you can do so by
disabling optional features at runtime and <a
href="{@docRoot}guide/topics/resources/providing-resources.html">providing app resources</a>
with alternatives for different configurations (such as different layouts for different
screen sizes).
If necessary, however, you can restrict your app's availability to devices through Google Play
Store based on the following device characteristics:</p>
<p>Google Play filters the applications that are visible to users, so
that users can see and download only those applications that are compatible with
their devices.</p>
<ul>
<li><a href="#Features">Device features</a>
<li><a href="#Version">Platform version</a>
<li><a href="#Screens">Screen configuration</a>
</ul>
<p style="margin-top:1em;">One of the ways Google Play filters applications is by
feature compatibility. To do this, Google Play checks the
<code>&lt;uses-feature&gt;</code> elements in each application's manifest, to
establish the app's feature needs. Google Play then shows or hides the application to
each user, based on a comparison with the features available on the user's
device.
<p style="margin-top:1em;">For information about other filters that you can
use to control the availability of your apps, see the
<h3 id="Features">Device features</h3>
<p>In order for you to manage your app’s availability based on device features,
Android defines <em>feature IDs</em> for any hardware or software feature
that may not be available on all devices. For instance, the
feature ID for the compass sensor is {@link
android.content.pm.PackageManager#FEATURE_SENSOR_COMPASS} and the feature ID for app widgets
is {@link android.content.pm.PackageManager#FEATURE_APP_WIDGETS}.</p>
<p>If necessary, you can prevent users from installing your app when their devices don't provide a
given feature by declaring it with a <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code &lt;uses-feature&gt;}</a>
element in your app's <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">manifest
file</a>.</p>
<p>For example, if your app does not make sense on a device that lacks a compass sensor,
you can declare the compass sensor as required with the following manifest tag:</p>
<pre>
&lt;manifest ... >
&lt;uses-feature android:name="android.hardware.sensor.compass"
android:required="true" />
...
&lt;/manifest>
</pre>
<p>Google Play Store compares the features your app requires to the features available on
each user's device to determine whether your app is compatible with each device.
If the device does not provide all the features your app requires, the user cannot install
your app.</p>
<p>However, if your app's primary functionality does not <em>require</em>
a device feature, you should set the <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html#required">{@code required}</a>
attribute to {@code "false"} and check
for the device feature at runtime. If the app feature is not available on the current device,
gracefully degrade the corresponding app feature. For example, you can query whether
a feature is available by calling
{@link android.content.pm.PackageManager#hasSystemFeature hasSystemFeature()} like this:</p>
<pre>
PackageManager pm = getPackageManager();
if (!pm.hasSystemFeature(PackageManager.FEATURE_SENSOR_COMPASS)) {
// This device does not have a compass, turn off the compass feature
disableCompassFeature();
}
</pre>
<p>For information about all the filters you can
use to control the availability of your app to users through Google Play Store, see the
<a href="{@docRoot}google/play/filters.html">Filters on Google Play</a>
document.</p>
</div>
</div>
<p>Android includes support for a lot of features, some hardware and some
software. Examples include compass and accelerometer sensors, cameras, and Live
Wallpapers. However, not every device will support every feature. For instance,
some devices don’t have the hardware horsepower to display Live Wallpapers
well.</p>
<p>To manage this, Android defines <em>feature IDs</em>. Every capability has a
corresponding feature ID defined by the Android platform. For instance, the
feature ID for compass is <code>“android.hardware.sensor.compass”</code>,
while the feature
ID for Live Wallpapers is <code>“android.software.live_wallpapers”</code>. Each of these IDs
also has a corresponding Java-language constant on the
{@link android.content.pm.PackageManager} class that you can use to query whether
feature is supported at runtime. As Android adds support for new features in
future versions, new feature IDs will be added as well.</p>
<p>When you write your application, you specify which features your app requires
by listing their feature IDs in <code>&lt;uses-feature&gt;</code> elements in
the <code>AndroidManifest.xml</code> file. This is the information that Google
Play uses to match your app to devices that can run it. For instance, if you
state that your app requires android.software.live_wallpapers, it won’t be shown
to devices that don’t support Live Wallpapers.</p>
<p>This puts you in total control of your app &mdash; because you don’t have to
declare these features. Consider an example involving cameras.</p>
<p>If you’re building a really impressive next-generation augmented-reality app,
your app won’t function at all without a camera. However, if you’re building a
shopping app that only uses the camera for barcode scanning, users without
cameras might still find it useful even if they can’t scan barcodes. While both
apps need to acquire the permission to access the camera, only the first app
needs to state that it requires a camera. (The shopping app can simply check at
runtime and disable the camera-related features if there’s no camera
present.)</p>
<p>Since only you can say what the best approach is for your app, Android
provides the tools and lets you make your own tradeoff between maximizing
audience size and minimizing development costs.</p>
<p class="note"><strong>Note:</strong> Some <a href=
"{@docRoot}guide/topics/security/permissions.html">system permissions</a> implicitly require the
availability of a device feature. For example, if your app requests permission to access to {@link
android.Manifest.permission#BLUETOOTH}, this implicitly requires the {@link
android.content.pm.PackageManager#FEATURE_BLUETOOTH} device feature. You can disable filtering based
on this feature and make your app available to devices without Bluetooth by setting the <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html#required">{@code required}</a> attribute
to {@code "false"} in the <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code &lt;uses-feature&gt;}</a> tag.
For more information about implicitly required device features, read <a href=
"{@docRoot}guide/topics/manifest/uses-feature-element.html#permissions">Permissions that Imply
Feature Requirements</a>.</p>
<h3 id="filtering">Filtering for business reasons</h3>
<p>It’s possible that you may need to restrict your app’s availability for
<h3 id="Versions">Platform version</h3>
<p>Different devices may run different versions of the Android platform,
such as Android 4.0 or Android 4.4. Each successive platform version often adds new APIs not
available in the previous version. To indicate which set of APIs are available, each
platform version specifies an <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">API level</a>. For instance,
Android 1.0 is API level 1 and Android 4.4 is API level 19.</p>
<p>The API level allows you to declare the minimum version with which your app is
compatible, using the <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">{@code
&lt;uses-sdk>}</a> manifest tag and its <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code minSdkVersion}</a> attribute.</p>
<p>For example, the <a href="{@docRoot}guide/topics/providers/calendar-provider.html">Calendar
Provider</a> APIs were added in Android 4.0 (API level 14). If your app cannot function without
these APIs, you should declare API level 14 as your app's minimum supported
version like this:</p>
<pre>
&lt;manifest ... >
&lt;uses-sdk android:minSdkVersion="14" android:targetSdkVersion="19" />
...
&lt;/manifest>
</pre>
<p>The <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code
minSdkVersion}</a> attribute declares the minimum version with which your app is compatible
and the <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code
targetSdkVersion}</a> attribute declares the highest version on which you've optimized
your app.</p>
<p>Each successive version of Android provides compatibility for apps that were built using
the APIs from previous platform versions, so your app should always be compitible with future
versions of Android while using the documented Android APIs.</p>
<p class="note"><strong>Note:</strong>
The <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code
targetSdkVersion}</a> attribute does not prevent your app from being installed on platform
versions that are higher than the specified value,
but it is important because it indicates to the system whether your
app should inherit behavior changes in newer versions. If you don't update the
<a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code
targetSdkVersion}</a> to the latest version, the system assumes that your
app requires some backward-compatibility behaviors when running on the latest version.
For example, among the <a href="{@docRoot}about/versions/android-4.4.html#Behaviors"
>behavior changes in Android 4.4</a>, alarms created with the {@link android.app.AlarmManager} APIs
are now inexact by default so the system can batch app alarms and preserve system power,
but the system will retain the previous API behavior for your app if your target API level
is lower than "19".</p>
<p>However, if your app uses APIs added in a more recent
platform version, but does not require them for its primary functionality,
you should check the API level at runtime and gracefully degrade
the corresponding features when the API level is too low. In this case,
set the <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code
minSdkVersion}</a> to the lowest value possible for your app's primary functionality,
then compare the current system's version, {@link android.os.Build.VERSION#SDK_INT}, to one the
codename constants in {@link android.os.Build.VERSION_CODES} that corresponds to the
API level you want to check. For example:</p>
<pre>
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB) {
// Running on something older than API level 11, so disable
// the drag/drop features that use {@link android.content.ClipboardManager} APIs
disableDragAndDrop();
}
</pre>
<h3 id="Screens">Screen configuration</h3>
<p>Android runs on devices of various sizes, from phones to tablets and TVs.
In order to categorize devices by their screen type, Android defines two characteristics for
each device: screen size (the physical size of the screen) and screen density (the physical
density of the pixels on the screen, known as <acronym title="dots per inch">DPI</acronym>).
To simplify the different configurations, Android generalizes these variants into groups that make
them easier to target:</p>
<ul>
<li>Four generalized sizes: small, normal, large, and xlarge.</li>
<li>And several generalized densities: mdpi (medium), hdpi (hdpi), xhdpi (extra high),
xxhdpi (extra-extra high), and others.</li>
</ul>
<p>By default, your app is compatible with all screen sizes and densities,
because the system makes the appropriate adjustments to your UI layout and image
resources as necessary for each screen. However, you should optimize the user experience for each
screen configuration by adding specialized layouts for different screen sizes and
optimized bitmap images for common screen densities.</p>
<p>For information about how to create alternative resources for different screens
and how to restrict your app to certain screen sizes when necessary, read <a
href="{@docRoot}training/basics/supporting-devices/screens.html">Supporting Different Screens</a>.
</p>
<h2 id="filtering">Controlling Your App's Availability for Business Reasons</h2>
<p>In addition to restricting your app's availability based on device characteristics,
it’s possible you may need to restrict your app’s availability for
business or legal reasons. For instance, an app that displays train schedules
for the London Underground is unlikely to be useful to users outside the United
Kingdom. Other apps might not be permitted in certain countries for business or
legal reasons. For cases such as these, Google Play itself provides
developers with filtering options that allow them control their app’s
availability for non-technical reasons.</p>
<p>The help information for Google Play provides full details, but in a
nutshell, developers can use the Google Play publisher UI to:</p>
<ul>
<li>List the countries an app is available in.</li>
<li>Select which carrier’s users are able to access the app.</li>
</ul>
Kingdom. For this type of situation, Google Play Store provides
filtering options in the developer console that allow you to control your app’s
availability for non-technical reasons such as the user's locale or wireless carrier.</p>
<p>Filtering for technical compatibility (such as required hardware components)
is always based on information contained within your <code>.apk</code> file. But
filtering for non-technical reasons (such as geographic restrictions) is always
handled in the Google Play user interface.</p>
<h3 id="futureproofing">Future-proofing</h3>
<p>There’s one additional quirk that we haven’t yet addressed: protecting apps
from changes made to future versions of Android. If the Android platform
introduces a new feature or changes how existing features are handled, what
happens to existing apps that were written without any knowledge of the new
behavior?</p>
<p>Simply put, Android commits to not making existing apps available to devices
where they won’t work properly, even when the platform changes. The best way to
explain this is through examples, so here are two:</p>
<ul>
<li>Android 1.0 through 1.5 required a 2 megapixel camera with auto-focus.
However, with version 1.6, Android devices were permitted to omit the auto-focus
capability, though a (fixed-focus) camera was still required. Some apps such as
barcode scanners do not function as well with cameras that do not auto-focus. To
prevent users from having a bad experience with those apps, existing apps that
obtain permission to use the Camera were assumed by default to require
auto-focus. This allowed Google Play to filter those apps from devices that
lack auto-focus.</li>
<li>Android 2.2, meanwhile, allowed the microphone to be optional on some
devices, such as set-top boxes. Android 2.2 included a new feature ID for the
microphone which allows developers to filter their apps if necessary, but
&mdash; as with camera &mdash; apps that obtain permission to record audio are
assumed to require the microphone feature by default. If your app can use a
microphone but doesn’t strictly need it, you can explicitly state that you don’t
require it; but unless you do that, your app won’t be shown to devices without
microphones.</li>
</ul>
<p>In other words, whenever Android introduces new features or changes existing
ones, we will always take steps to protect existing applications so that they
don’t end up being available to devices where they won’t work.</p>
<p>This is implemented, in part, using the <code>aapt</code> tool in the SDK.
To see which features your app explicitly requires or is implicitly assumed to
require, you can use the command <code>aapt dump badging</code>.</p>
<h3 id="conclusion">Conclusion</h3>
<p>The goal of Android is to create a huge installed base for developers to take
advantage of. One of the ways we will achieve this is through different kinds of
hardware running the same software environment. But we also recognize that only
developers know which kinds of devices their apps make sense on. We’ve built in
tools to the SDK and set up policies and requirements to ensure that developers
remain in control of their apps, today and in the future. With the information
you just read, and the resources listed in the sidebar of this document, you
can publish your app with the confidence that only users who can run it will
see it.</p>
<p>For more information about Android device compatibility, please visit:</p>
<p style="margin-left:2em;"><a href="http://source.android.com/compatibility/index.html">http://source.android.com/compatibility/index.html</a></p>
is always based on information contained within your APK file. But
filtering for non-technical reasons (such as geographic locale) is always
handled in the Google Play developer console.</p>
<div class="next-docs">
<div class="col-6">
<h2 class="norule">Continue reading about:</h2>
<dl>
<dt><a
href="{@docRoot}guide/topics/resources/providing-resources.html">Providing Resources</a></dt>
<dd>Information about how Android apps are structured to separate app resources from the
app code, including how you can provide alternative resources for specific device
configurations.
</dd>
<dt><a href="{@docRoot}google/play/filters.html">Filters on Google Play</a></dt>
<dd>Information about the different ways that Google Play Store can prevent your app
from being installed on different devices.</dd>
</dl>
</div>
<div class="col-6">
<h2 class="norule">You might also be interested in:</h2>
<dl>
<dt><a href="{@docRoot}guide/topics/security/permissions.html"
>System Permissions</a></dt>
<dd>How Android restricts app access to certain APIs with a permission system that requires
the user's consent for your app to use those APIs.</dd>
</dl>
</div>
</div>

3
docs/html/guide/practices/screens_support.jd
View File

@@ -25,8 +25,7 @@ page.title=Supporting Multiple Screens
<li><a href="#qualifiers">Using configuration qualifiers</a></li>
<li><a href="#DesigningResources">Designing alternative layouts and drawables</a></li>
</ol></li>
<li><a href="#DeclaringTabletLayouts">Declaring Tablet Layouts for Android 3.2</a> <span
class="new">new!</span>
<li><a href="#DeclaringTabletLayouts">Declaring Tablet Layouts for Android 3.2</a>
<ol>
<li><a href="#NewQualifiers">Using new size qualifiers</a></li>
<li><a href="#ConfigurationExamples">Configuration examples</a></li>

2
docs/html/guide/topics/manifest/manifest-intro.jd
View File

@@ -1,4 +1,4 @@
page.title=The AndroidManifest.xml File
page.title=App Manifest
@jd:body
<div id="qv-wrapper">

72
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View File

@@ -1,4 +1,4 @@
page.title=Permissions
page.title=System Permissions
@jd:body
<div id="qv-wrapper">
@@ -20,10 +20,6 @@ page.title=Permissions
</ol>
</div>
</div>
<p>This document describes how application developers can use the
security features provided by Android. A more general <a
href="http://source.android.com/tech/security/index.html"> Android Security
Overview</a> is provided in the Android Open Source Project.</p>
<p>Android is a privilege-separated operating system, in which each
application runs with a distinct system identity (Linux user ID and group
@@ -33,7 +29,13 @@ Linux thereby isolates applications from each other and from the system.</p>
<p>Additional finer-grained security features are provided through a
"permission" mechanism that enforces restrictions on the specific operations
that a particular process can perform, and per-URI permissions for granting
ad-hoc access to specific pieces of data.</p>
ad hoc access to specific pieces of data.</p>
<p>This document describes how application developers can use the
security features provided by Android. A more general <a
href="http://source.android.com/tech/security/index.html"> Android Security
Overview</a> is provided in the Android Open Source Project.</p>
<a name="arch"></a>
<h2>Security Architecture</h2>
@@ -42,10 +44,10 @@ ad-hoc access to specific pieces of data.</p>
application, by default, has permission to perform any operations that would
adversely impact other applications, the operating system, or the user. This
includes reading or writing the user's private data (such as contacts or
e-mails), reading or writing another application's files, performing
network access, keeping the device awake, etc.</p>
emails), reading or writing another application's files, performing
network access, keeping the device awake, and so on.</p>
<p>Because Android sandboxes applications from each other, applications
<p>Because each Android application operates in a process sandbox, applications
must explicitly share resources and data. They do this by declaring the
<em>permissions</em> they need for additional capabilities not provided by
the basic sandbox. Applications statically declare the permissions they
@@ -65,10 +67,10 @@ other.</p>
<a name="signing"></a>
<h2>Application Signing</h2>
<p>All Android applications (.apk files) must be signed with a certificate
<p>All APKs ({@code .apk} files) must be signed with a certificate
whose private key is held by their developer. This certificate identifies
the author of the application. The certificate does <em>not</em> need to be
signed by a certificate authority: it is perfectly allowable, and typical,
signed by a certificate authority; it is perfectly allowable, and typical,
for Android applications to use self-signed certificates. The purpose of
certificates in Android is to distinguish application authors. This allows
the system to grant or deny applications access to <a
@@ -86,7 +88,7 @@ device. On a different device, the same package may have a different UID;
what matters is that each package has a distinct UID on a given device.</p>
<p>Because security enforcement happens at the
process level, the code of any two packages can not normally
process level, the code of any two packages cannot normally
run in the same process, since they need to run as different Linux users.
You can use the {@link android.R.attr#sharedUserId} attribute in the
<code>AndroidManifest.xml</code>'s
@@ -114,7 +116,7 @@ been set appropriately so any other application can see it.</p>
<h2>Using Permissions</h2>
<p>A basic Android application has no permissions associated with it by default,
meaning it can not do anything that would adversely impact the user experience
meaning it cannot do anything that would adversely impact the user experience
or any data on the device. To make use of protected features of the device,
you must include in your <code>AndroidManifest.xml</code> one or more
<code>{@link android.R.styleable#AndroidManifestUsesPermission &lt;uses-permission&gt;}</code>
@@ -133,9 +135,9 @@ specify:</p>
granted to it by the package installer, based on checks against the
signatures of the applications declaring those permissions and/or interaction
with the user. <em>No</em> checks with the user
are done while an application is running: it either was granted a particular
are done while an application is running; the app is either granted a particular
permission when installed, and can use that feature as desired, or the
permission was not granted and any attempt to use the feature will fail
permission is not granted and any attempt to use the feature fails
without prompting the user.</p>
<p>Often times a permission failure will result in a {@link
@@ -146,6 +148,12 @@ being delivered to each receiver, after the method call has returned, so you
will not receive an exception if there are permission failures. In almost all
cases, however, a permission failure will be printed to the system log.</p>
<p>However, in a normal user situation (such as when the app is installed
from Google Play Store), an app cannot be installed if the user does not grant the app
each of the requested permissions. So you generally don't need to worry about runtime failures
caused by missing permissions because the mere fact that the app is installed at all
means that your app has been granted its desired permissions.</p>
<p>The permissions provided by the Android system can be found at {@link
android.Manifest.permission}. Any application may also define and enforce its
own permissions, so this is not a comprehensive list of all possible
@@ -433,3 +441,37 @@ android:grantUriPermissions} attribute or
{@link android.content.Context#checkUriPermission Context.checkUriPermission()}
methods.</p>
<div class="next-docs">
<div class="col-6">
<h2 class="norule">Continue reading about:</h2>
<dl>
<dt><a href="{@docRoot}guide/topics/manifest/uses-feature-element.html#permissions"
>Permissions that Imply Feature Requirements</a></dt>
<dd>Information about how requesting some permissions will implicitly restrict your app
to devices that include the corresponding hardware or software feature.</dd>
<dt><a href="{@docRoot}guide/topics/manifest/uses-permission-element.html">{@code
&lt;uses-permission>}</a></dt>
<dd>API reference for the manifest tag that declare's your app's required system permissions.
</dd>
<dt>{@link android.Manifest.permission}</dt>
<dd>API reference for all system permissions.</dd>
</dl>
</div>
<div class="col-6">
<h2 class="norule">You might also be interested in:</h2>
<dl>
<dt><a href="{@docRoot}guide/practices/compatibility.html"
>Device Compatibility</a></dt>
<dd>Information about Android works on different types of devices and an introduction
to how you can optimize your app for each device or restrict your app's availability
to different devices.</dd>
<dt><a href="{@docRoot}http://source.android.com/devices/tech/security/index.html"
class="external-link">Android Security Overview</a></dt>
<dd>A detailed discussion about the Android platform's security model.</dd>
</dl>
</div>
</div>