docs/html/guide/appendix/glossary.jd - platform/frameworks/base - Git at Google


            
            page.title=Glossary

            
            excludeFromSuggestions=true

            
            @jd:body


            <p>The list below defines some of the basic terminology of the Android platform. </p>

            
                <dl>

            
                <dt id="apk">.apk file</dt> <dd>Android application package file. Each

            
                Android application is compiled and packaged in a single file that

            
                includes all of the application's code (.dex files), resources, assets,

            
                and manifest file. The application package file can have any name but

            
                <em>must</em> use the <code>.apk</code> extension. For example:

            
                <code>myExampleAppname.apk</code>. For convenience, an application package

            
                file is often referred to as an ".apk".

            
                <p>Related: <a href="#application">Application</a>.</p>

            
            </dd>


                <dt id="dex">.dex file </dt>

            
                <dd>Compiled Android application code file.

            
                   <p>Android programs are compiled into .dex (Dalvik Executable) files, which

            
                    are in turn zipped into a single .apk file on the device. .dex files can

            
                    be created by automatically translating compiled applications written in

            
                    the Java programming language.</dd>


                <dt id="action">Action</dt>

            
                <dd>A description of something that an Intent sender wants done. An action is

            
                    a string value assigned to an Intent. Action strings can be defined by Android

            
                    or by a third-party developer. For example, android.intent.action.VIEW

            
                    for a Web URL, or com.example.rumbler.SHAKE_PHONE for a custom application

            
                    to vibrate the phone.

            
                <p>Related: <a href="#intent">Intent</a>.</p>

            
                </dd>


                <dt id="activity">Activity</dt>

            
                <dd>A single screen in an application, with supporting Java code, derived

            
                from the {@link android.app.Activity} class. Most commonly, an activity is

            
                visibly represented by a full screen window that can receive and handle UI

            
                events and perform complex tasks, because of the Window it uses to render

            
                its window. Though an Activity is typically full screen, it can also be

            
                floating or transparent.</dd>


                <dt id="adb">adb</dt>

            
                <dd>Android Debug Bridge, a command-line debugging application included with the

            
                    SDK. It provides tools to browse the device, copy tools on the device, and

            
                    forward ports for debugging. If you are developing in Eclipse using the

            
            		ADT Plugin, adb is integrated into your development environment. See

            
            		<a href="{@docRoot}tools/help/adb.html">Android Debug Bridge</a>

            
            		for more information. </dd>


                <dt id="application">Application</dt>

            
                <dd>From a component perspective, an Android application consists of one

            
                or more activities, services, listeners, and intent receivers. From a

            
                source file perspective, an Android application consists of code,

            
                resources, assets, and a single manifest. During compilation, these files

            
                are packaged in a single file called an application package file (.apk).

            
                <p>Related: <a href="#apk">.apk</a>, <a href="#activity">Activity</a></p></dd>


                <dt id="canvas">Canvas</dt>

            
                <dd>A drawing surface that handles compositing of the actual bits against

            
                a Bitmap or Surface object. It has methods for standard computer drawing

            
                of bitmaps, lines, circles, rectangles, text, and so on, and is bound to a

            
                Bitmap or Surface. Canvas is the simplest, easiest way to draw 2D objects

            
                on the screen. However, it does not support hardware acceleration, as

            
                OpenGL ES does. The base class is {@link android.graphics.Canvas}.

            
                <p>Related: <a href="#drawable">Drawable</a>, <a href="#opengles">OpenGL

            
                ES</a>.</p></dd>


                <dt id="contentprovider">Content Provider</dt>

            
                <dd>A data-abstraction layer that you can use to safely expose your

            
                application's data to other applications. A content provider is built on

            
                the {@link android.content.ContentProvider} class, which handles content

            
                query strings of a specific format to return data in a specific format.

            
                See <a href="{@docRoot}guide/topics/providers/content-providers.html">

            
            	Content Providers</a> topic for more information.

            
                <p>Related: <a href="#uri">URI Usage in Android</a></p></dd>


                <dt id="dalvik">Dalvik</dt>

            
                <dd>The Android platform's virtual machine. The Dalvik VM is an

            
                interpreter-only virtual machine that executes files in the Dalvik

            
                Executable (.dex) format, a format that is optimized for efficient storage

            
                and memory-mappable execution. The virtual machine is register-based, and

            
                it can run classes compiled by a Java language compiler that have been

            
                transformed into its native format using the included &quot;dx&quot; tool.

            
                The VM runs on top of Posix-compliant operating systems, which it relies

            
                on for underlying functionality (such as threading and low level memory

            
                management). The Dalvik core class library is intended to provide a

            
                familiar development base for those used to programming with Java Standard

            
                Edition, but it is geared specifically to the needs of a small mobile

            
                device.</dd>


                <dt id="ddms">DDMS</dt>

            
                <dd>Dalvik Debug Monitor Service, a GUI debugging application included

            
                with the SDK. It provides screen capture, log dump, and process

            
                examination capabilities. If you are developing in Eclipse using the ADT

            
                Plugin, DDMS is integrated into your development environment. See <a

            
                href="{@docRoot}tools/debugging/ddms.html">Using DDMS</a> to learn more about the program.</dd>


                <dt id="dialog">Dialog</dt> <dd> A floating window that acts as a lightweight

            
                form. A dialog can have button controls only and is intended to perform a

            
                simple action (such as button choice) and perhaps return a value. A dialog

            
                is not intended to persist in the history stack, contain complex layout,

            
                or perform complex actions. Android provides a default simple dialog for

            
                you with optional buttons, though you can define your own dialog layout.

            
                The base class for dialogs is {@link android.app.Dialog Dialog}.

            
                <p>Related: <a href="#activity">Activity</a>.</p></dd>


                <dt id="drawable">Drawable</dt>

            
                <dd>A compiled visual resource that can be used as a background, title, or

            
                other part of the screen. A drawable is typically loaded into another UI

            
                element, for example as a background image. A drawable is not able to

            
                receive events, but does assign various other properties such as "state"

            
                and scheduling, to enable subclasses such as animation objects or image

            
                libraries. Many drawable objects are loaded from drawable resource files

            
                &mdash; xml or bitmap files that describe the image. Drawable resources

            
                are compiled into subclasses of {@link android.graphics.drawable}. For

            
                more information about drawables and other resources, see <a

            
                href="{@docRoot}guide/topics/resources/resources-i18n.html">Resources</a>.

            
                <p>Related: <a href="#resources">Resources</a>, <a href="#canvas">Canvas

            
                </a></p></dd>


                <dt id="intent">Intent</dt>

            
                <dd>An message object that you can use to launch or communicate with other

            
                applications/activities asynchronously. An Intent object is an instance of

            
                {@link android.content.Intent}. It includes several criteria fields that you can

            
                supply, to determine what application/activity receives the Intent and

            
                what the receiver does when handling the Intent. Available criteria include

            
                include the desired action, a category, a data string, the MIME type of

            
                the data, a handling class, and others. An application sends

            
                an Intent to the Android system, rather than sending it directly to

            
                another application/activity. The application can send the Intent to a

            
                single target application or it can send it as a broadcast, which can in

            
                turn be handled by multiple applications sequentially. The Android system

            
                is responsible for resolving the best-available receiver for each Intent,

            
                based on the criteria supplied in the Intent and the Intent Filters

            
                defined by other applications. For more information, see <a

            
                href="{@docRoot}guide/components/intents-filters.html">Intents and

            
                Intent Filters</a>.

            
                <p>Related: <a href="#intentfilter">Intent Filter</a>, <a

            
                href="#broadcastreceiver">Broadcast Receiver</a>.</p></dd>


                <dt id="intentfilter">Intent Filter</dt>

            
                <dd>A filter object that an application declares in its manifest file, to

            
                tell the system what types of Intents each of its components is willing to

            
                accept and with what criteria. Through an intent filter, an application

            
                can express interest in specific data types, Intent actions, URI formats,

            
                and so on. When resolving an Intent, the system evaluates all of the

            
                available intent filters in all applications and passes the Intent to the

            
                application/activity that best matches the Intent and criteria. For more

            
                information, see <a

            
                href="{@docRoot}guide/components/intents-filters.html">Intents and

            
                Intent Filters</a>.

            
                <p>Related: <a href="#intent">Intent</a>, <a

            
                href="#broadcastreceiver">Broadcast Receiver</a>.</p></dd>


                <dt id="broadcastreceiver">Broadcast Receiver </dt>

            
                <dd>An application class that listens for Intents that are broadcast,

            
                rather than being sent to a single target application/activity. The system

            
                delivers a broadcast Intent to all interested broadcast receivers, which

            
                handle the Intent sequentially.

            
                <p>Related: <a href="#intent">Intent</a>, <a href="#intentfilter">Intent

            
                Filter</a>.</p> </dd>


                <dt id="layoutresource">Layout Resource</dt>

            
                <dd>An XML file that describes the layout of an Activity screen.

            
                <p>Related: <a href="#resources">Resources</a></p></dd>


                <dt id="manifest">Manifest File</dt>

            
                <dd>An XML file that each application must define, to describe the

            
                application's package name, version, components (activities, intent

            
                filters, services), imported libraries, and describes the various

            
                activities, and so on. See <a

            
                href="{@docRoot}guide/topics/manifest/manifest-intro.html">The

            
                AndroidManifest.xml File</a> for complete information.</dd>


                <dt id="ninepatch">Nine-patch / 9-patch / Ninepatch image</dt>

            
                <dd>A resizeable bitmap resource that can be used for backgrounds or other

            
                images on the device. See <a

            
                href="{@docRoot}guide/topics/resources/available-resources.html#ninepatch">

            
                Nine-Patch Stretchable Image</a> for more information.

            
                <p>Related: <a href="#resources">Resources</a>.</p></dd>


                <dt id="opengles">OpenGL ES</dt>

            
                <dd> Android provides OpenGL ES libraries that you can use for fast,

            
                complex 3D images. It is harder to use than a Canvas object, but

            
                better for 3D objects. The {@link android.opengl} and

            
                {@link javax.microedition.khronos.opengles} packages expose

            
                OpenGL ES functionality.

            
                <p>Related: <a href="#canvas">Canvas</a>, <a href="#surface">Surface</a></p></dd>


                <dt id="resources">Resources</dt>

            
                <dd>Nonprogrammatic application components that are external to the

            
                compiled application code, but which can be loaded from application code

            
                using a well-known reference format. Android supports a variety of

            
                resource types, but a typical application's resources would consist of UI

            
                strings, UI layout components, graphics or other media files, and so on.

            
                An application uses resources to efficiently support localization and

            
                varied device profiles and states. For example, an application would

            
                include a separate set of resources for each supported local or device

            
                type, and it could include layout resources that are specific to the

            
                current screen orientation (landscape or portrait). For more information

            
                about resources, see <a

            
                href="{@docRoot}guide/topics/resources/index.html"> Resources and

            
                Assets</a>. The resources of an application are always stored in the

            
                <code>res/*</code> subfolders of the project. </dd>


                <dt id="service">Service</dt>

            
                <dd>An object of class {@link android.app.Service} that runs in the

            
                background (without any UI presence) to perform various persistent

            
                actions, such as playing music or monitoring network activity.

            
                <p>Related: <a href="#activity">Activity</a></p></dd>


                <dt id="surface">Surface</dt>

            
                <dd>An object of type {@link android.view.Surface} representing a block of

            
                memory that gets composited to the screen. A Surface holds a Canvas object

            
                for drawing, and provides various helper methods to draw layers and resize

            
                the surface. You should not use this class directly; use

            
                {@link android.view.SurfaceView} instead.

            
                <p>Related: <a href="#canvas">Canvas</a></p></dd>


                <dt id="surfaceview">SurfaceView</dt>

            
                <dd>A View object that wraps a Surface for drawing, and exposes methods to

            
                specify its size and format dynamically. A SurfaceView provides a way to

            
                draw independently of the UI thread for resource-intensive operations

            
                (such as games or camera previews), but it uses extra memory as a result.

            
                SurfaceView supports both Canvas and OpenGL ES graphics. The base class is

            
                {@link android.view.SurfaceView}.

            
                <p>Related: <a href="#canvas">Surface</a></p></dd>


                <dt id="theme">Theme</dt>

            
                <dd>A set of properties (text size, background color, and so on) bundled

            
                together to define various default display settings. Android provides a

            
                few standard themes, listed in {@link android.R.style} (starting with

            
                &quot;Theme_&quot;). </dd>


                <dt id="uri">URIs in Android</dt>

            
                <dd>Android uses URI strings as the basis for requesting data in a content

            
                provider (such as to retrieve a list of contacts) and for requesting

            
                actions in an Intent (such as opening a Web page in a browser). The URI

            
                scheme and format is specialized according to the type of use, and an

            
                application can handle specific URI schemes and strings in any way it

            
                wants. Some URI schemes are reserved by system components. For example,

            
                requests for data from a content provider must use the

            
                <code>content://</code>. In an Intent, a URI using an <code>http://</code>

            
                scheme will be handled by the browser. </dd>


                <dt id="view">View</dt>

            
            	<dd>An object that draws to a rectangular area on the screen and handles

            
                click, keystroke, and other interaction events. A View is a base class for

            
                most layout components of an Activity or Dialog screen (text boxes,

            
                windows, and so on). It receives calls from its parent object (see

            
                viewgroup, below)to draw itself, and informs its parent object about where

            
                and how big it would like to be (which may or may not be respected by the

            
                parent). For more information, see {@link android.view.View}.

            
                <p>Related: <a href="#viewgroup">Viewgroup</a>, <a href="#widget">Widget

            
                </a></p></dd>


                <dt id="viewgroup">Viewgroup</dt>

            
                <dd> A container object that groups a set of child Views. The viewgroup is

            
                responsible for deciding where child views are positioned and how large

            
                they can be, as well as for calling each to draw itself when appropriate.

            
                Some viewgroups are invisible and are for layout only, while others have

            
                an intrinsic UI (for instance, a scrolling list box). Viewgroups are all

            
                in the {@link android.widget widget} package, but extend

            
                {@link android.view.ViewGroup ViewGroup}.

            
                <p>Related: <a href="#view">View</a></p></dd>


                <dt id="widget">Widget</dt>

            
                <dd>One of a set of fully implemented View subclasses that render form

            
                elements and other UI components, such as a text box or popup menu.

            
                Because a widget is fully implemented, it handles measuring and drawing

            
                itself and responding to screen events. Widgets are all in the

            
                {@link android.widget} package. </dd>


             <!--

            
                <dt id="panel">Panel</dt>

            
                <dd> A panel is a concept not backed by a specific class. It is a View of

            
                some sort that is tied in closely to a parent window, but can handle

            
                clicks and perform simple functions related to its parent. A panel floats

            
                in front of its parent, and is positioned relative to it. A common example

            
                of a panel (implemented by Android) is the options menu available to every

            
                screen. At present, there are no specific classes or methods for creating

            
                a panel &mdash; it's more of a general idea. </dd>

            
            -->


                <dt id="panel">Window</dt>

            
                <dd>In an Android application, an object derived from the abstract class

            
                {@link android.view.Window} that specifies the elements of a generic

            
                window, such as the look and feel (title bar text, location and content of

            
                menus, and so on). Dialog and Activity use an implementation of this class

            
                to render a window. You do not need to implement this class or use windows

            
                in your application. </dd>


            </dl>
	page.title=Glossary
	excludeFromSuggestions=true
	@jd:body

	<p>The list below defines some of the basic terminology of the Android platform. </p>
	<dl>
	<dt id="apk">.apk file</dt> <dd>Android application package file. Each
	Android application is compiled and packaged in a single file that
	includes all of the application's code (.dex files), resources, assets,
	and manifest file. The application package file can have any name but
	<em>must</em> use the <code>.apk</code> extension. For example:
	<code>myExampleAppname.apk</code>. For convenience, an application package
	file is often referred to as an ".apk".
	<p>Related: <a href="#application">Application</a>.</p>
	</dd>

	<dt id="dex">.dex file </dt>
	<dd>Compiled Android application code file.
	<p>Android programs are compiled into .dex (Dalvik Executable) files, which
	are in turn zipped into a single .apk file on the device. .dex files can
	be created by automatically translating compiled applications written in
	the Java programming language.</dd>

	<dt id="action">Action</dt>
	<dd>A description of something that an Intent sender wants done. An action is
	a string value assigned to an Intent. Action strings can be defined by Android
	or by a third-party developer. For example, android.intent.action.VIEW
	for a Web URL, or com.example.rumbler.SHAKE_PHONE for a custom application
	to vibrate the phone.
	<p>Related: <a href="#intent">Intent</a>.</p>
	</dd>

	<dt id="activity">Activity</dt>
	<dd>A single screen in an application, with supporting Java code, derived
	from the {@link android.app.Activity} class. Most commonly, an activity is
	visibly represented by a full screen window that can receive and handle UI
	events and perform complex tasks, because of the Window it uses to render
	its window. Though an Activity is typically full screen, it can also be
	floating or transparent.</dd>

	<dt id="adb">adb</dt>
	<dd>Android Debug Bridge, a command-line debugging application included with the
	SDK. It provides tools to browse the device, copy tools on the device, and
	forward ports for debugging. If you are developing in Eclipse using the
	ADT Plugin, adb is integrated into your development environment. See
	<a href="{@docRoot}tools/help/adb.html">Android Debug Bridge</a>
	for more information. </dd>

	<dt id="application">Application</dt>
	<dd>From a component perspective, an Android application consists of one
	or more activities, services, listeners, and intent receivers. From a
	source file perspective, an Android application consists of code,
	resources, assets, and a single manifest. During compilation, these files
	are packaged in a single file called an application package file (.apk).
	<p>Related: <a href="#apk">.apk</a>, <a href="#activity">Activity</a></p></dd>

	<dt id="canvas">Canvas</dt>
	<dd>A drawing surface that handles compositing of the actual bits against
	a Bitmap or Surface object. It has methods for standard computer drawing
	of bitmaps, lines, circles, rectangles, text, and so on, and is bound to a
	Bitmap or Surface. Canvas is the simplest, easiest way to draw 2D objects
	on the screen. However, it does not support hardware acceleration, as
	OpenGL ES does. The base class is {@link android.graphics.Canvas}.
	<p>Related: <a href="#drawable">Drawable</a>, <a href="#opengles">OpenGL
	ES</a>.</p></dd>

	<dt id="contentprovider">Content Provider</dt>
	<dd>A data-abstraction layer that you can use to safely expose your
	application's data to other applications. A content provider is built on
	the {@link android.content.ContentProvider} class, which handles content
	query strings of a specific format to return data in a specific format.
	See <a href="{@docRoot}guide/topics/providers/content-providers.html">
	Content Providers</a> topic for more information.
	<p>Related: <a href="#uri">URI Usage in Android</a></p></dd>

	<dt id="dalvik">Dalvik</dt>
	<dd>The Android platform's virtual machine. The Dalvik VM is an
	interpreter-only virtual machine that executes files in the Dalvik
	Executable (.dex) format, a format that is optimized for efficient storage
	and memory-mappable execution. The virtual machine is register-based, and
	it can run classes compiled by a Java language compiler that have been
	transformed into its native format using the included "dx" tool.
	The VM runs on top of Posix-compliant operating systems, which it relies
	on for underlying functionality (such as threading and low level memory
	management). The Dalvik core class library is intended to provide a
	familiar development base for those used to programming with Java Standard
	Edition, but it is geared specifically to the needs of a small mobile
	device.</dd>

	<dt id="ddms">DDMS</dt>
	<dd>Dalvik Debug Monitor Service, a GUI debugging application included
	with the SDK. It provides screen capture, log dump, and process
	examination capabilities. If you are developing in Eclipse using the ADT
	Plugin, DDMS is integrated into your development environment. See <a
	href="{@docRoot}tools/debugging/ddms.html">Using DDMS</a> to learn more about the program.</dd>

	<dt id="dialog">Dialog</dt> <dd> A floating window that acts as a lightweight
	form. A dialog can have button controls only and is intended to perform a
	simple action (such as button choice) and perhaps return a value. A dialog
	is not intended to persist in the history stack, contain complex layout,
	or perform complex actions. Android provides a default simple dialog for
	you with optional buttons, though you can define your own dialog layout.
	The base class for dialogs is {@link android.app.Dialog Dialog}.
	<p>Related: <a href="#activity">Activity</a>.</p></dd>

	<dt id="drawable">Drawable</dt>
	<dd>A compiled visual resource that can be used as a background, title, or
	other part of the screen. A drawable is typically loaded into another UI
	element, for example as a background image. A drawable is not able to
	receive events, but does assign various other properties such as "state"
	and scheduling, to enable subclasses such as animation objects or image
	libraries. Many drawable objects are loaded from drawable resource files
	— xml or bitmap files that describe the image. Drawable resources
	are compiled into subclasses of {@link android.graphics.drawable}. For
	more information about drawables and other resources, see <a
	href="{@docRoot}guide/topics/resources/resources-i18n.html">Resources</a>.
	<p>Related: <a href="#resources">Resources</a>, <a href="#canvas">Canvas
	</a></p></dd>

	<dt id="intent">Intent</dt>
	<dd>An message object that you can use to launch or communicate with other
	applications/activities asynchronously. An Intent object is an instance of
	{@link android.content.Intent}. It includes several criteria fields that you can
	supply, to determine what application/activity receives the Intent and
	what the receiver does when handling the Intent. Available criteria include
	include the desired action, a category, a data string, the MIME type of
	the data, a handling class, and others. An application sends
	an Intent to the Android system, rather than sending it directly to
	another application/activity. The application can send the Intent to a
	single target application or it can send it as a broadcast, which can in
	turn be handled by multiple applications sequentially. The Android system
	is responsible for resolving the best-available receiver for each Intent,
	based on the criteria supplied in the Intent and the Intent Filters
	defined by other applications. For more information, see <a
	href="{@docRoot}guide/components/intents-filters.html">Intents and
	Intent Filters</a>.
	<p>Related: <a href="#intentfilter">Intent Filter</a>, <a
	href="#broadcastreceiver">Broadcast Receiver</a>.</p></dd>

	<dt id="intentfilter">Intent Filter</dt>
	<dd>A filter object that an application declares in its manifest file, to
	tell the system what types of Intents each of its components is willing to
	accept and with what criteria. Through an intent filter, an application
	can express interest in specific data types, Intent actions, URI formats,
	and so on. When resolving an Intent, the system evaluates all of the
	available intent filters in all applications and passes the Intent to the
	application/activity that best matches the Intent and criteria. For more
	information, see <a
	href="{@docRoot}guide/components/intents-filters.html">Intents and
	Intent Filters</a>.
	<p>Related: <a href="#intent">Intent</a>, <a
	href="#broadcastreceiver">Broadcast Receiver</a>.</p></dd>

	<dt id="broadcastreceiver">Broadcast Receiver </dt>
	<dd>An application class that listens for Intents that are broadcast,
	rather than being sent to a single target application/activity. The system
	delivers a broadcast Intent to all interested broadcast receivers, which
	handle the Intent sequentially.
	<p>Related: <a href="#intent">Intent</a>, <a href="#intentfilter">Intent
	Filter</a>.</p> </dd>

	<dt id="layoutresource">Layout Resource</dt>
	<dd>An XML file that describes the layout of an Activity screen.
	<p>Related: <a href="#resources">Resources</a></p></dd>

	<dt id="manifest">Manifest File</dt>
	<dd>An XML file that each application must define, to describe the
	application's package name, version, components (activities, intent
	filters, services), imported libraries, and describes the various
	activities, and so on. See <a
	href="{@docRoot}guide/topics/manifest/manifest-intro.html">The
	AndroidManifest.xml File</a> for complete information.</dd>

	<dt id="ninepatch">Nine-patch / 9-patch / Ninepatch image</dt>
	<dd>A resizeable bitmap resource that can be used for backgrounds or other
	images on the device. See <a
	href="{@docRoot}guide/topics/resources/available-resources.html#ninepatch">
	Nine-Patch Stretchable Image</a> for more information.
	<p>Related: <a href="#resources">Resources</a>.</p></dd>

	<dt id="opengles">OpenGL ES</dt>
	<dd> Android provides OpenGL ES libraries that you can use for fast,
	complex 3D images. It is harder to use than a Canvas object, but
	better for 3D objects. The {@link android.opengl} and
	{@link javax.microedition.khronos.opengles} packages expose
	OpenGL ES functionality.
	<p>Related: <a href="#canvas">Canvas</a>, <a href="#surface">Surface</a></p></dd>

	<dt id="resources">Resources</dt>
	<dd>Nonprogrammatic application components that are external to the
	compiled application code, but which can be loaded from application code
	using a well-known reference format. Android supports a variety of
	resource types, but a typical application's resources would consist of UI
	strings, UI layout components, graphics or other media files, and so on.
	An application uses resources to efficiently support localization and
	varied device profiles and states. For example, an application would
	include a separate set of resources for each supported local or device
	type, and it could include layout resources that are specific to the
	current screen orientation (landscape or portrait). For more information
	about resources, see <a
	href="{@docRoot}guide/topics/resources/index.html"> Resources and
	Assets</a>. The resources of an application are always stored in the
	<code>res/*</code> subfolders of the project. </dd>

	<dt id="service">Service</dt>
	<dd>An object of class {@link android.app.Service} that runs in the
	background (without any UI presence) to perform various persistent
	actions, such as playing music or monitoring network activity.
	<p>Related: <a href="#activity">Activity</a></p></dd>

	<dt id="surface">Surface</dt>
	<dd>An object of type {@link android.view.Surface} representing a block of
	memory that gets composited to the screen. A Surface holds a Canvas object
	for drawing, and provides various helper methods to draw layers and resize
	the surface. You should not use this class directly; use
	{@link android.view.SurfaceView} instead.
	<p>Related: <a href="#canvas">Canvas</a></p></dd>

	<dt id="surfaceview">SurfaceView</dt>
	<dd>A View object that wraps a Surface for drawing, and exposes methods to
	specify its size and format dynamically. A SurfaceView provides a way to
	draw independently of the UI thread for resource-intensive operations
	(such as games or camera previews), but it uses extra memory as a result.
	SurfaceView supports both Canvas and OpenGL ES graphics. The base class is
	{@link android.view.SurfaceView}.
	<p>Related: <a href="#canvas">Surface</a></p></dd>

	<dt id="theme">Theme</dt>
	<dd>A set of properties (text size, background color, and so on) bundled
	together to define various default display settings. Android provides a
	few standard themes, listed in {@link android.R.style} (starting with
	"Theme_"). </dd>

	<dt id="uri">URIs in Android</dt>
	<dd>Android uses URI strings as the basis for requesting data in a content
	provider (such as to retrieve a list of contacts) and for requesting
	actions in an Intent (such as opening a Web page in a browser). The URI
	scheme and format is specialized according to the type of use, and an
	application can handle specific URI schemes and strings in any way it
	wants. Some URI schemes are reserved by system components. For example,
	requests for data from a content provider must use the
	<code>content://</code>. In an Intent, a URI using an <code>http://</code>
	scheme will be handled by the browser. </dd>

	<dt id="view">View</dt>
	<dd>An object that draws to a rectangular area on the screen and handles
	click, keystroke, and other interaction events. A View is a base class for
	most layout components of an Activity or Dialog screen (text boxes,
	windows, and so on). It receives calls from its parent object (see
	viewgroup, below)to draw itself, and informs its parent object about where
	and how big it would like to be (which may or may not be respected by the
	parent). For more information, see {@link android.view.View}.
	<p>Related: <a href="#viewgroup">Viewgroup</a>, <a href="#widget">Widget
	</a></p></dd>

	<dt id="viewgroup">Viewgroup</dt>
	<dd> A container object that groups a set of child Views. The viewgroup is
	responsible for deciding where child views are positioned and how large
	they can be, as well as for calling each to draw itself when appropriate.
	Some viewgroups are invisible and are for layout only, while others have
	an intrinsic UI (for instance, a scrolling list box). Viewgroups are all
	in the {@link android.widget widget} package, but extend
	{@link android.view.ViewGroup ViewGroup}.
	<p>Related: <a href="#view">View</a></p></dd>

	<dt id="widget">Widget</dt>
	<dd>One of a set of fully implemented View subclasses that render form
	elements and other UI components, such as a text box or popup menu.
	Because a widget is fully implemented, it handles measuring and drawing
	itself and responding to screen events. Widgets are all in the
	{@link android.widget} package. </dd>

	<!--
	<dt id="panel">Panel</dt>
	<dd> A panel is a concept not backed by a specific class. It is a View of
	some sort that is tied in closely to a parent window, but can handle
	clicks and perform simple functions related to its parent. A panel floats
	in front of its parent, and is positioned relative to it. A common example
	of a panel (implemented by Android) is the options menu available to every
	screen. At present, there are no specific classes or methods for creating
	a panel — it's more of a general idea. </dd>
	-->

	<dt id="panel">Window</dt>
	<dd>In an Android application, an object derived from the abstract class
	{@link android.view.Window} that specifies the elements of a generic
	window, such as the look and feel (title bar text, location and content of
	menus, and so on). Dialog and Activity use an implementation of this class
	to render a window. You do not need to implement this class or use windows
	in your application. </dd>


	</dl>