guide/appendix/glossary.jd

page.title=Glossary
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<h1>Android Glossary</h1>
<p>The following terms are used in these documents. </p>
<dl>
    <dt>.apk extension </dt>
    <dd>The extension for an Android package file, which typically contains all of the files
        related to a single Android application.  The file itself is a compressed collection
        of an AndroidManifest.xml file, application code (.dex files), resource
        files, and other files.  A project is compiled into a single .apk file.</dd>
    <dt>.dex extension </dt>
    <dd>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>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. </dd>
    <dt>Activity</dt>
    <dd>A single screen in an application, with supporting Java code, derived from
        the {@link android.app.Activity} class. </dd>
    <dt>adb</dt>
    <dd>Android Debug Bridge, a command-line debugging application shipped with the
        SDK. It provides tools to browse the device, copy tools on the device, and
        forward ports for debugging. See <a href="adb.html">Using adb</a> for more information. </dd>
    <dt>Application</dt>
    <dd>A collection of one or more activities, services, listeners, and intent receivers.
        An application has a single manifest, and is compiled into a single .apk
        file on the device. </dd>
    <dt>Content Provider</dt>
    <dd>A class built on {@link android.content.ContentProvider} that handles content
        query strings of a specific format to return data in a specific format.
        See <a href="{@docRoot}devel/data/contentproviders.html">Reading
        and writing data to a content provider</a> for information on using
        content providers. </dd>
    <dt>Content URI</dt>
    <dd>A type of URI. See the URI entry. </dd>
    <dt>Dalvik</dt>
    <dd>The name of Android'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>DDMS</dt>
    <dd>Dalvik Debug Monitor Service, a GUI debugging application shipped with the
        SDK. It provides screen capture, log dump, and process examination capabilities.
        See Using the <a href="{@docRoot}reference/ddms.html">Dalvik
        Debug Monitor Server</a> to learn more about this
        program. </dd>
    <dt>Drawable</dt>
    <dd>A compiled visual resource that can be used as a background, title, or other
        part of the screen. It is compiled into an {@link android.graphics.drawable}
        subclass. </dd>
    <dt>Intent</dt>
    <dd>A class ({@link android.content.Intent}) that contains several fields describing
        what a caller would like to do. The caller sends this intent to Android's
        intent resolver, which looks through the intent filters of all applications
        to find the activity most suited to handle this intent. Intent fields include
        the desired action, a category, a data string, the MIME type of the data, a handling
        class, and other restrictions. </dd>
    <dt>Intent Filter</dt>
    <dd>Activities and intent receivers include one or more filters in their manifest
        to describe what kinds of intents or messages they can handle or want to
        receive. An intent filter lists a set of requirements, such as data type,
        action requested, and URI format, that the Intent or message must fulfill.
        For activities, Android searches for the activity with the most closely matching
        valid match between the Intent and the activity filter. For messages, Android
        will forward a message to all receivers with matching intent filters. </dd>
    <dt></dt>
    <dt>Intent Receiver </dt>
    <dd>An application class that listens for messages broadcast by calling {@link
        android.content.Context#sendBroadcast(android.content.Intent) Context.sendBroadcast()}.
        For example code, see <a href="{@docRoot}kb/commontasks.html#broadcastreceivers">Listening
        for and broadcasting global messages</a>.</dd>
    <dt>Layout resource </dt>
    <dd>An XML file that describes the layout of an Activity screen. </dd>
    <dt>Manifest</dt>
    <dd>An XML file associated with each Application that describes the various activies,
        intent filters, services, and other items that it exposes. See <a href="{@docRoot}devel/bblocks-manifest.html">AndroidManifest.xml
        File Details</a>.</dd>
    <dt>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}reference/available-resources.html#ninepatch">Nine-Patch Stretchable
        Image</a> for more information. </dd>
    <dt>Query String</dt>
    <dd>A type of URI. See the URI entry. </dd>
    <dt>Resource</dt>
    <dd>A user-supplied XML, bitmap, or other file, entered into an application build
        process, which can later be loaded from code. Android can accept resources
        of many types; see <a href="{@docRoot}devel/resources-i18n.html">Resources</a> for a full description.
        Application-defined resources should be stored in the <code>res/</code> subfolders. </dd>
    <dt>Service</dt>
    <dd>A class that runs in the background to perform various persistent actions,
    such as playing music or monitoring network activity. </dd>
    <dt>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>URIs</dt>
    <dd>Android uses URI strings both for requesting data (e.g., a list of contacts)
        and for requesting actions (e.g., opening a Web page in a browser). Both
        are valid URI strings, but have different values. All requests for data must
        start with the string &quot;content://&quot;. Action strings are valid URIs
        that can be handled appropriately by applications on the device; for example,
        a URI starting with &quot;http://"; will be handled by the browser. </dd>
</dl>
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