| page.title=Resources and Internationalization |
| parent.title=Resources and Assets |
| parent.link=index.html |
| @jd:body |
| |
| <div id="qv-wrapper"> |
| <div id="qv"> |
| |
| <h2>Key classes</h2> |
| <ol> |
| <li>{@link android.content.res.Resources}</li> |
| </ol> |
| |
| <h2>In this document</h2> |
| <ol> |
| <li><a href="#intro">Introduction</a></li> |
| <li><a href="#CreatingResources">Creating Resources</a></li> |
| <li><a href="#UsingResources">Using Resources</a> |
| <ol> |
| <li><a href="#ResourcesInCode">Using Resources in Code</a></li> |
| <li><a href="#ReferencesToResources">References to Resources</a></li> |
| <li><a href="#ReferencesToThemeAttributes">References to Theme Attributes</a></li> |
| <li><a href="#UsingSystemResources">Using System Resources</a></li> |
| </ol> |
| </li> |
| <li><a href="#AlternateResources">Alternate Resources</a></li> |
| <li><a href="#ResourcesTerminology">Terminology</a></li> |
| <li><a href="#i18n">Internationalization (I18N)</a></li> |
| </ol> |
| </div> |
| </div> |
| |
| <p>Resources are external files (that is, non-code files) that are used by |
| your code and compiled into your application at build time. Android |
| supports a number of different kinds of resource files, including XML, |
| PNG, and JPEG files. The XML files have very different formats depending |
| on what they describe. This document describes what kinds of files are |
| supported, and the syntax or format of each.</p> |
| <p>Resources are externalized from source code, and XML files are compiled into |
| a binary, fast loading format for efficiency reasons. Strings, likewise, are compressed |
| into a more efficient storage form. It is for these reasons that we have these |
| different resource types in the Android platform.</p> |
| |
| <p>This is a fairly technically dense document, and together with the |
| <a href="available-resources.html">Available Resources</a> |
| document, they cover a lot of information about resources. It is not necessary |
| to know this document by heart to use Android, but rather to know that the |
| information is here when you need it.</p> |
| |
| <a name="intro"></a> |
| <h2>Introduction</h2> |
| |
| <p>This topic includes a terminology list associated with resources, and a series |
| of examples of using resources in code. For a complete guide to the supported |
| Android resource types, see |
| <a href="available-resources.html">Available Resources</a>. |
| </p> |
| <p>The Android resource system keeps track of all non-code |
| assets associated with an application. You use the |
| {@link android.content.res.Resources Resources} class to access your |
| application's resources; the Resources instance associated with your |
| application can generally be found through |
| {@link android.content.Context#getResources Context.getResources()}.</p> |
| <p>An application's resources are compiled into the application |
| binary at build time for you by the build system. To use a resource, |
| you must install it correctly in the source tree and build your |
| application. As part of the build process, symbols for each |
| of the resources are generated that you can use in your source |
| code -- this allows the compiler to verify that your application code matches |
| up with the resources you defined.</p> |
| |
| <p>The rest of this section is organized as a tutorial on how to |
| use resources in an application.</p> |
| |
| <a name="CreatingResources" id="CreatingResources"></a> |
| <h2>Creating Resources</h2> |
| |
| <p>Android supports string, bitmap, and many other types of resource. The syntax and format |
| of each, and where they're stored, depends upon the type of object. In |
| general, though, you create resources from three types of files: XML files |
| (everything but bitmaps and raw), bitmap files(for images) and Raw files (anything |
| else, for example sound files, etc.). In fact, there are two different types of |
| XML file as well, those that get compiled as-is into the package, and those that |
| are used to generate resources by aapt. Here is a list of each |
| resource type, the format of the file, a description of the file, and details |
| of any XML files. </p> |
| |
| <p>You will create and store your resource files under the appropriate |
| subdirectory under the <code>res/</code> directory in your project. Android |
| has a resource compiler (aapt) that compiles resources according to which |
| subfolder they are in, and the format of the file. Table 1 shows a list of the file |
| types for each resource. See the |
| <a href="available-resources.html">Available Resources</a> for |
| descriptions of each type of object, the syntax, and the format or syntax of |
| the containing file.</p> |
| <p class="caption">Table 1</p> |
| <table width="100%" border="1"> |
| <tr> |
| <th scope="col">Directory</th> |
| <th scope="col">Resource Types </th> |
| </tr> |
| <tr> |
| <td><code>res/anim/</code></td> |
| <td>XML files that are compiled into |
| <a href="available-resources.html#animationdrawable">frame by |
| frame animation</a> or |
| <a href="available-resources.html#tweenedanimation">tweened |
| animation</a> objects </td> |
| </tr> |
| <tr> |
| <td><code>res/drawable/</code></td> |
| <td><p>.png, .9.png, .jpg files that are compiled into the following |
| Drawable resource subtypes:</p> |
| <ul class="nolist"> |
| <li><a href="available-resources.html#imagefileresources">bitmap files</a></li> |
| <li><a href="available-resources.html#ninepatch">9-patches (resizable bitmaps)</a></li> |
| </ul> |
| <p>To get a resource of this type, use <code>mContext.getResources().getDrawable(R.drawable.<em>imageId</em>)</code></p> |
| <p class="note"><strong>Note:</strong> Image resources placed in here may |
| be automatically optimized with lossless image compression by the |
| <a href="{@docRoot}guide/developing/tools/aapt.html">aapt</a> tool. For example, a true-color PNG |
| that does not require more than 256 colors may be converted to an 8-bit PNG with a color palette. |
| This will result in an image of equal quality but which requires less memory. So be aware that the |
| image binaries placed in this directory can change during the build. If you plan on reading |
| an image as a bit stream in order to convert it to a bitmap, put your images in the |
| <code>res/raw/</code> folder instead, where they will not be optimized.</p> |
| </td> |
| </tr> |
| <tr> |
| <td><code>res/layout/</code></td> |
| <td>XML files that are compiled into screen layouts (or part of a screen). |
| See <a href="{@docRoot}guide/topics/ui/declaring-layout.html">Declaring Layout</a>.</td> |
| </tr> |
| <tr> |
| <td><code>res/values/</code></td> |
| <td><p>XML files that can be compiled into many kinds of resource.</p> |
| <p class="note"><strong>Note:</strong> Unlike the other res/ folders, this one |
| can hold any number of files that hold descriptions of resources to create |
| rather than the resources themselves. The XML element types control |
| where these resources are placed under the R class.</p> |
| <p>While the files can be named anything, these are |
| the typical files in this folder (the convention is to name |
| the file after the type of elements defined within):</p> |
| <ul> |
| <li><strong>arrays.xml</strong> to define arrays </li> |
| <!-- TODO: add section on arrays --> |
| <li><strong>colors.xml</strong> to define <a href="available-resources.html#colordrawableresources">color |
| drawables</a> and <a href="#colorvals">color string values</a>. |
| Use <code>Resources.getDrawable()</code> and |
| <code>Resources.getColor(), respectively,</code> |
| to get these resources.</li> |
| <li><strong>dimens.xml</strong> to define <a href="available-resources.html#dimension">dimension value</a>. Use <code>Resources.getDimension()</code> to get |
| these resources.</li> |
| <li><strong>strings.xml</strong> to define <a href="available-resources.html#stringresources">string</a> values (use either |
| <code>Resources.getString</code> or preferably <code>Resources.getText()</code> |
| to get |
| these resources. <code>getText()</code> will retain any rich text styling |
| which is usually desirable for UI strings.</li> |
| <li><strong>styles.xml</strong> to define <a href="available-resources.html#stylesandthemes">style</a> objects.</li> |
| </ul></td> |
| </tr> |
| <tr> |
| <td><code>res/xml/</code></td> |
| <td>Arbitrary XML files that are compiled and can be read at run time by |
| calling {@link android.content.res.Resources#getXml(int) Resources.getXML()}.</td> |
| </tr> |
| <tr> |
| <td><code>res/raw/</code></td> |
| <td>Arbitrary files to copy directly to the device. They are added uncompiled |
| to the compressed file that your application build produces. To use these |
| resources in your application, call {@link android.content.res.Resources#openRawResource(int) |
| Resources.openRawResource()} with the resource ID, which is R.raw.<em>somefilename</em>.</td> |
| </tr> |
| </table> |
| <p>Resources are compiled into the final APK file. Android creates a wrapper class, |
| called R, that you can use to refer to these resources in your code. R contains subclasses |
| named according to the path and file name of the source file</p> |
| <a name="colorvals" id="colorvals"></a> |
| <h3>Global Resource Notes</h3> |
| <ul> |
| <li>Several resources allow you to define colors. Android accepts color values |
| written in various web-style formats -- a hexadecimal constant in any of the |
| following forms: #RGB, #ARGB, #RRGGBB, #AARRGGBB. </li> |
| <li>All color values support setting an alpha channel value, where the first |
| two hexadecimal numbers specify the transparency. Zero in the alpha channel |
| means transparent. The default value is opaque. </li> |
| </ul> |
| <a name="UsingResources" id="UsingResources"></a> |
| <h2>Using Resources </h2> |
| <p>This section describes how to use the resources you've created. It includes the |
| following topics:</p> |
| <ul> |
| <li><a href="#ResourcesInCode">Using resources in code</a> - How to call |
| resources in your code to instantiate them. </li> |
| <li><a href="#ReferencesToResources">Referring to resources from other resources</a> - |
| You can reference resources from other resources. This lets you reuse common |
| resource values inside resources. </li> |
| <li><a href="#AlternateResources">Supporting Alternate Resources for Alternate |
| Configurations</a> - You can specify different resources |
| to load, depending on the language or display configuration of the host |
| hardware. </li> |
| </ul> |
| <p>At compile time, Android generates a class named R that contains resource identifiers |
| to all the resources in your program. This class contains several subclasses, |
| one for each type of resource supported by Android, and for which you provided |
| a resource file. Each class contains one or more identifiers for the compiled resources, |
| that you use in your code to load the resource. Here is a small resource file |
| that contains string, layout (screens or parts of screens), and image resources.</p> |
| <p class="note"><strong>Note:</strong> the R class is an auto-generated file and is not |
| designed to be edited by hand. It will be automatically re-created as needed when |
| the resources are updated.</p> |
| <pre class="prettyprint">package com.android.samples; |
| public final class R { |
| public static final class string { |
| public static final int greeting=0x0204000e; |
| public static final int start_button_text=0x02040001; |
| public static final int submit_button_text=0x02040008; |
| public static final int main_screen_title=0x0204000a; |
| }; |
| public static final class layout { |
| public static final int start_screen=0x02070000; |
| public static final int new_user_pane=0x02070001; |
| public static final int select_user_list=0x02070002; |
| |
| }; |
| public static final class drawable { |
| public static final int company_logo=0x02020005; |
| public static final int smiling_cat=0x02020006; |
| public static final int yellow_fade_background=0x02020007; |
| public static final int stretch_button_1=0x02020008; |
| |
| }; |
| }; |
| </pre> |
| <a name="ResourcesInCode" id="ResourcesInCode"></a> |
| <h3>Using Resources in Code </h3> |
| |
| <p>Using resources in code is just a matter of knowing the full resource ID |
| and what type of object your resource has been compiled into. Here is the |
| syntax for referring to a resource:</p> |
| <p><code>R.<em>resource_type</em>.<em>resource_name</em></code></p> |
| <p>or</p> |
| <p><code>android.R.<em>resource_type</em>.<em>resource_name</em></code></p> |
| |
| <p>Where <code>resource_type</code> is the R subclass that holds a specific type |
| of resource. <code>resource_name</code> is the <em>name</em> attribute for resources |
| defined in XML files, or the file name (without the extension) for resources |
| defined by other file types. Each type of resource will be added to a specific |
| R subclass, depending on the type of resource it is; to learn which R subclass |
| hosts your compiled resource type, consult the |
| <a href="available-resources.html">Available Resources</a> document. Resources compiled by your own application can |
| be referred to without a package name (simply as |
| <code>R.<em>resource_type</em>.<em>resource_name</em></code>). Android contains |
| a number of standard resources, such as screen styles and button backgrounds. To |
| refer to these in code, you must qualify them with <code>android</code>, as in |
| <code>android.R.drawable.button_background</code>.</p> |
| |
| <p>Here are some good and bad examples of using compiled resources in code:</p> |
| |
| <pre class="prettyprint">// Load a background for the current screen from a drawable resource. |
| this.getWindow().setBackgroundDrawableResource(R.drawable.my_background_image); |
| |
| // WRONG Sending a string resource reference into a |
| // method that expects a string. |
| this.getWindow().setTitle(R.string.main_title); |
| |
| // RIGHT Need to get the title from the Resources wrapper. |
| this.getWindow().setTitle(Resources.getText(R.string.main_title)); |
| |
| // Load a custom layout for the current screen. |
| setContentView(R.layout.main_screen); |
| |
| // Set a slide in animation for a ViewFlipper object. |
| mFlipper.setInAnimation(AnimationUtils.loadAnimation(this, |
| R.anim.hyperspace_in)); |
| |
| // Set the text on a TextView object. |
| TextView msgTextView = (TextView)findViewByID(R.id.msg); |
| msgTextView.setText(R.string.hello_message); </pre> |
| |
| <a name="ReferencesToResources" id="ReferencesToResources"></a> |
| <h3>References to Resources</h3> |
| |
| <p>A value supplied in an attribute (or resource) can also be a reference to |
| a resource. This is often used in layout files to supply strings (so they |
| can be localized) and images (which exist in another file), though a reference |
| can be any resource type including colors and integers.</p> |
| |
| <p>For example, if we have |
| <a href="available-resources.html#colordrawableresources">color |
| resources</a>, we can write a layout file that sets the text color size to be |
| the value contained in one of those resources:</p> |
| |
| <pre> |
| <?xml version="1.0" encoding="utf-8"?> |
| <EditText id="text" |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| android:layout_width="fill_parent" android:layout_height="fill_parent" |
| <strong>android:textColor="@color/opaque_red"</strong> |
| android:text="Hello, World!" /> |
| </pre> |
| |
| <p>Note here the use of the '@' prefix to introduce a resource reference -- the |
| text following that is the name of a resource in the form |
| of <code>@[package:]type/name</code>. In this case we didn't need to specify |
| the package because we are referencing a resource in our own package. To |
| reference a system resource, you would need to write:</p> |
| |
| <pre> |
| <?xml version="1.0" encoding="utf-8"?> |
| <EditText id="text" |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| android:layout_width="fill_parent" android:layout_height="fill_parent" |
| android:textColor="@<strong>android:</strong>color/opaque_red" |
| android:text="Hello, World!" /> |
| </pre> |
| |
| <p>As another example, you should always use resource references when supplying |
| strings in a layout file so that they can be localized:</p> |
| |
| <pre> |
| <?xml version="1.0" encoding="utf-8"?> |
| <EditText id="text" |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| android:layout_width="fill_parent" android:layout_height="fill_parent" |
| android:textColor="@android:color/opaque_red" |
| android:text="@string/hello_world" /> |
| </pre> |
| |
| <p>This facility can also be used to create references between resources. |
| For example, we can create new drawable resources that are aliases for |
| existing images:</p> |
| |
| <pre> |
| <?xml version="1.0" encoding="utf-8"?> |
| <resources> |
| <drawable id="my_background">@android:drawable/theme2_background</drawable> |
| </resources> |
| </pre> |
| |
| <a name="ReferencesToThemeAttributes"></a> |
| <h3>References to Theme Attributes</h3> |
| |
| <p>Another kind of resource value allows you to reference the value of an |
| attribute in the current theme. This attribute reference can <em>only</em> |
| be used in style resources and XML attributes; it allows you to customize the |
| look of UI elements by changing them to standard variations supplied by the |
| current theme, instead of supplying more concrete values.</p> |
| |
| <p>As an example, we can use this in our layout to set the text color to |
| one of the standard colors defined in the base system theme:</p> |
| |
| <pre> |
| <?xml version="1.0" encoding="utf-8"?> |
| <EditText id="text" |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| android:layout_width="fill_parent" android:layout_height="fill_parent" |
| <strong>android:textColor="?android:textDisabledColor"</strong> |
| android:text="@string/hello_world" /> |
| </pre> |
| |
| <p>Note that this is very similar to a resource reference, except we are using |
| an '?' prefix instead of '@'. When you use this markup, you are supplying |
| the name of an attribute resource that will be looked up in the theme -- |
| because the resource tool knows that an attribute resource is expected, |
| you do not need to explicitly state the type (which would be |
| <code>?android:attr/android:textDisabledColor</code>).</p> |
| |
| <p>Other than using this resource identifier to find the value in the |
| theme instead of raw resources, the name syntax is identical to the '@' format: |
| <code>?[namespace:]type/name</code> with the type here being optional.</p> |
| |
| <a name="UsingSystemResources"></a> |
| <h3>Using System Resources</h3> |
| |
| <p>Many resources included with the system are available to applications. |
| All such resources are defined under the class "android.R". For example, |
| you can display the standard application icon in a screen with the following |
| code:</p> |
| |
| <pre class="prettyprint"> |
| public class MyActivity extends Activity |
| { |
| public void onStart() |
| { |
| requestScreenFeatures(FEATURE_BADGE_IMAGE); |
| |
| super.onStart(); |
| |
| setBadgeResource(android.R.drawable.sym_def_app_icon); |
| } |
| } |
| </pre> |
| |
| <p>In a similar way, this code will apply to your screen the standard |
| "green background" visual treatment defined by the system:</p> |
| |
| <pre class="prettyprint"> |
| public class MyActivity extends Activity |
| { |
| public void onStart() |
| { |
| super.onStart(); |
| |
| setTheme(android.R.style.Theme_Black); |
| } |
| } |
| </pre> |
| |
| <a name="AlternateResources" id="AlternateResources"></a> |
| <h2>Alternate Resources (for alternate languages and configurations)</h2> |
| |
| <p>You can supply different resources for your application to use depending on the UI |
| language or hardware configuration on the device. Note that although you can |
| include different string, layout, and other resources, the SDK does not expose |
| methods to let you specify which alternate resource set to load. Android |
| detects the proper set for the hardware and location, and loads them as |
| appropriate. Users can select alternate language settings using the settings |
| panel on the device. </p> |
| <p>To include alternate resources, create parallel resource folders with |
| qualifiers appended to the folder names, indicating the configuration it |
| applies to (language, screen orientation, and so on). For example, here is a |
| project that holds one string resource file for English, and another for |
| French:</p> |
| |
| <pre> |
| MyApp/ |
| res/ |
| values-en/ |
| strings.xml |
| values-fr/ |
| strings.xml |
| </pre> |
| |
| <p>Android supports several types of qualifiers, with various values for each. |
| Append these to the end of the resource folder name, separated by dashes. You |
| can add multiple qualifiers to each folder name, but they must appear in the |
| order they are listed here. For example, a folder containing drawable |
| resources for a fully specified configuration would look like this:</p> |
| |
| <pre> |
| MyApp/ |
| res/ |
| drawable-en-rUS-large-long-port-mdpi-finger-keysexposed-qwerty-navexposed-dpad-480x320/ |
| </pre> |
| |
| <p>More typically, you will only specify a few specific configuration options. You may drop any of the values from the |
| complete list, as long as the remaining values are still in the same |
| order:</p> |
| |
| <pre> |
| MyApp/ |
| res/ |
| drawable-en-rUS-finger/ |
| drawable-port/ |
| drawable-port-mdpi/ |
| drawable-qwerty/ |
| </pre> |
| <p>Table 2 lists the valid folder-name qualifiers, in order of precedence. Qualifiers that are listed higher in the table take precedence over those listed lower, as described in <a href="#best-match">How Android finds the best matching directory</a>. </p> |
| <p class="caption" id="table2">Table 2</p> |
| <table border="1"> |
| <tr> |
| <th> Qualifier </th> |
| <th> Values </th> |
| </tr> |
| <tr> |
| <td>MCC and MNC</td> |
| <td><p>The mobile country code optionally followed by mobile network code |
| from the SIM in the device. For example |
| <code>mcc310</code> (U.S. on any carrier); |
| <code>mcc310-mnc004</code> (U.S., Verizon brand); |
| <code>mcc208-mnc00</code> (France, Orange brand); |
| <code>mcc234-mnc00</code> (U.K., BT brand). |
| </p><p> |
| If the device uses a radio connection (GSM phone), the MCC will come |
| from the SIM, and the MNC will come from the network to which the |
| device is attached. You might sometimes use the MCC alone, for example |
| to include country-specific legal resources in your application. If |
| your application specifies resources for a MCC/MNC combination, those |
| resources can only be used if both the MCC and the MNC match. </p></td> |
| </tr> |
| <tr> |
| <td>Language and region</td> |
| <td><p>The two letter <a href="http://www.loc.gov/standards/iso639-2/php/code_list.php">ISO |
| 639-1</a> language code optionally followed by a two letter |
| <a href="http://www.iso.org/iso/en/prods-services/iso3166ma/02iso-3166-code-lists/list-en1.html">ISO |
| 3166-1-alpha-2</a> region code (preceded by lowercase "r"). For example |
| <code>fr</code>, <code>en-rUS</code>, <code>fr-rFR</code>, <code>es-rES</code>. |
| </p><p> |
| The codes are <em>not</em> case-sensitive; the r prefix is used to |
| distinguish the region portion. |
| You cannot specify a region alone, but you can specify a language alone, |
| for example <code>en</code>, <code>fr</code>, <code>es</code>.</p> </td> |
| </tr> |
| <tr> |
| <td>Screen dimensions</td> |
| <td><p><code>small</code>, <code>normal</code>, <code>large</code> |
| </p><p> |
| Specify that the resource is for a particular class of screen. |
| The meanings of these are:</p> |
| <ul> |
| <li> <b>Normal screens</b> are based on the traditional Android HVGA |
| medium density screen. A screen is considered to be normal if it is |
| at least this size (independent of density) and not large. Examples |
| of such screens a WQVGA low density, HVGA medium density, WVGA |
| high density. |
| <li> <b>Small screens</b> are based on the space available on a |
| QVGA low density screen. Considering a portrait HVGA display, this has |
| the same available width but less height -- it is 3:4 vs. HVGA's |
| 2:3 aspect ratio. Examples are QVGA low density and VGA high |
| density. |
| <li> <b>Large screens</b> are based on the space available on a |
| VGA medium density screen. Such a screen has significantly more |
| available space in both width and height than an HVGA display. |
| Examples are VGA and WVGA medium density screens. |
| </td> |
| </tr> |
| <tr> |
| <td>Wider/taller screens</td> |
| <td><p><code>long</code>, <code>notlong</code> |
| </p><p> |
| Specify that the resource is for a taller/wider than traditional |
| screen. This is based purely on the aspect ration of the screen: |
| QVGA, HVGA, and VGA are notlong; WQVGA, WVGA, FWVGA are long. Note |
| that long may mean either wide or tall, depending on the current |
| orientation.</p> |
| </td> |
| </tr> |
| <tr> |
| <td>Screen orientation</td> |
| <td><p><code>port</code>, <code>land</code>, <code>square</code> |
| </p><p> |
| Specifies that the resource is for a screen that is tall (port) |
| or wide (land); square is not currently used.</p> |
| </td> |
| </tr> |
| <tr> |
| <td>Screen pixel density</td> |
| <td><p><code>ldpi</code>, <code>mdpi</code>, <code>hdpi</code>, <code>nodpi</code> |
| </p><p> |
| Specifies the screen density the resource is defined for. The medium |
| density of traditional HVGA screens (mdpi) is defined to be approximately |
| 160dpi; low density (ldpi) is 120, and high density (hdpi) is 240. There |
| is thus a 4:3 scaling factor between each density, so a 9x9 bitmap |
| in ldpi would be 12x12 is mdpi and 16x16 in hdpi. The special |
| <code>nodpi</code> density can be used with bitmap resources to prevent |
| them from being scaled at load time to match the device density. |
| </p><p> |
| When Android selects which resource files to use, |
| it handles screen density differently than the other qualifiers. |
| In step 1 of <a href="#best-match">How Android finds the best |
| matching directory</a> (below), screen density is always considered to |
| be a match. In step 4, if the qualifier being considered is screen |
| density, Android will select the best final match at that point, |
| without any need to move on to step 5. |
| </p><p> |
| You can also specify explicit densities like <code>92dpi</code> |
| or <code>108dpi</code>, but these are not fully supported by the |
| system so should not be used. |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td>Touchscreen type</td> |
| <td><code>notouch</code>, <code>stylus</code>, <code>finger</code></td> |
| </tr> |
| <tr> |
| <td>Whether the keyboard is available to the user</td> |
| <td><p><code>keysexposed</code>, <code>keyshidden</code>, <code>keyssoft</code> |
| </p><p> |
| If your application has specific resources that should only be used with a soft keyboard, use the <code>keyssoft</code> value. If no <code>keyssoft</code> resources are available (only <code>keysexposed</code> and <code>keyshidden</code>) and the device shows a soft keyboard, the system will use <code>keysexposed</code> resources.</p> </td> |
| </tr> |
| <tr> |
| <td>Primary text input method</td> |
| <td><code>nokeys</code>, <code>qwerty</code>, <code>12key</code> </td> |
| </tr> |
| <tr> |
| <td>Whether the navigation keys are available to the user</td> |
| <td><p><code>navexposed</code>, <code>navhidden</code> |
| </p><p> |
| If the hardware's navigation keys are currently available to |
| the user, the navexposed resources will be used; if they are not |
| available (such as behind a closed lid), navhidden will be used.</p></td> |
| </tr> |
| <tr> |
| <td>Primary non-touchscreen<br /> |
| navigation method</td> |
| <td><code>nonav</code>, <code>dpad</code>, <code>trackball</code>, <code>wheel</code> </td> |
| </tr> |
| <tr> |
| <td>Screen dimensions</td> |
| <td><code>320x240</code>, <code>640x480</code>, etc. The larger dimension |
| must be specified first. This configuration is deprecated and |
| should not be used; use instead screen dimension, wider/taller |
| screens, and screen orientation described above.</td> |
| </tr> |
| <tr> |
| <td>SDK version</td> |
| <td>The SDK version supported by the device, for example <code>v3</code>. The Android 1.0 SDK is <code>v1, </code> the 1.1 SDK is <code>v2</code>, and the 1.5 SDK is <code>v3</code>.</td> |
| </tr> |
| <tr> |
| <td>(Minor version)</td> |
| <td>(You cannot currently specify minor version. It is always set to 0.)</td> |
| </tr> |
| </table> |
| |
| <p>This list does not include device-specific parameters such as carrier, |
| branding, device/hardware, or manufacturer. Everything that an application |
| needs to know about the device that it is running on is encoded via the |
| resource qualifiers in the table above.</p> |
| |
| <p>All resource directories, qualified and unqualified, live under the <code>res/</code> folder. Here are some guidelines on qualified resource directory names:</p> |
| |
| <ul> |
| <li>You can specify multiple qualifiers, separated by dashes. For example, <code>drawable-en-rUS-land</code> will apply to US-English |
| devices in landscape orientation. </li> |
| <li>The qualifiers must be in the order listed in <a href="#table2">Table 2</a> above. For example: |
| <ul> |
| <li>Correct: <code>values-mcc460-nokeys/</code></li> |
| <li>Incorrect: <code>values-nokeys-mcc460/</code></li> |
| </ul> |
| </li> |
| <li>Values are case-insensitive. The resource compiler converts folder names |
| to lower case before processing to avoid problems in case-insensitive |
| file systems. On case-sensitive file systems, you should keep all names |
| lower-case or at least use a consistent case to protect your future |
| sanity when trying to find a resource file.</li> |
| <li>Only one value for each qualifier type is supported. For example, if you want to use exactly the same drawable files for Spain and France, you will need two resource directories, such as <code>drawable-rES/</code> and <code>drawable-rFR/</code>, containing identical files. You cannot |
| have a directory named <code>drawable-rES-rFR/</code>. </li> |
| <li>Qualified directories cannot be nested. For example, you cannot have <code>res/drawable/drawable-en</code>. </li> |
| </ul> |
| |
| <h3>How resources are referenced in code</h3> |
| <p>All resources will be referenced in code or resource reference syntax by |
| their simple, undecorated names. So if a resource were named this:<br /> |
| <code>MyApp/res/drawable-port-mdpi/myimage.png</code><br /> |
| It would be referenced as this:<br /> |
| <code>R.drawable.myimage</code> (code)<br /> |
| <code>@drawable/myimage</code> (XML)</p> |
| <p>If several drawable directories are available, Android will select one of them (as described below) and load <code>myimage.png</code> from it.</p> |
| <h3 id="best-match">How Android finds the best matching directory </h3> |
| |
| <p>Android will pick which of the various underlying resource files should be |
| used at runtime, depending on the current configuration of the device. |
| The example used here assumes the following device configuration:</p> |
| <blockquote> |
| <p>Locale = <code>en-GB</code><br> |
| Screen orientation = <code>port</code><br> |
| Screen pixel density = <code>mdpi</code><br> |
| Touchscreen type = <code>notouch</code><br> |
| Primary text input method = <code>12key</code><br> |
| </p> |
| </blockquote> |
| <p>Here is how Android makes the selection: </p> |
| <ol> |
| <li> |
| Eliminate resource files that contradict the |
| device configuration. For example, assume that the following resource directories are available for drawables. The <code>drawable-fr-rCA/</code> directory will be eliminated, because it contradicts the locale of the device.<br> |
| <pre>MyApp/res/drawable/ |
| MyApp/res/drawable-en/ |
| <strike>MyApp/res/drawable-fr-rCA/</strike> |
| MyApp/res/drawable-en-port/ |
| MyApp/res/drawable-en-notouch-12key/ |
| MyApp/res/drawable-port-ldpi/ |
| MyApp/res/drawable-port-notouch-12key</pre> |
| <strong>Exception: </strong>Screen pixel density is the one qualifier that is not used to eliminate files. Even though the screen density of the device is medium dpi, <code>drawable-port-ldpi/</code> is not eliminated from the list, because every screen density is considered to be a |
| match at this point.</li> |
| <li>From <a href="#table2">Table 2</a>, pick the highest-precedence qualifier that remains in the list. (Start with MCC, then move down through the list.) </li> |
| <li>Do any of the available resource directories include this qualifier? </li> |
| <ul> |
| <li>If No, return to step 2 and look at the next qualifier listed in Table 2. In our example, the answer is "no" until we reach Language.</li> |
| <li>If Yes, move on to step 4.</li> |
| </ul> |
| <li>Eliminate resource directories that do not include this qualifier. In our example, we eliminate all the directories that do not include a language qualifier. </li> |
| <pre><strike>MyApp/res/drawable/</strike> |
| MyApp/res/drawable-en/ |
| MyApp/res/drawable-en-port/ |
| MyApp/res/drawable-en-notouch-12key/ |
| <strike>MyApp/res/drawable-port-ldpi/</strike> |
| <strike>MyApp/res/drawable-port-notouch-12key</strike></pre> |
| <strong>Exception:</strong> If the qualifier in question is screen pixel density, Android will select the option that most closely matches the device, and the selection process will be complete. In general, Android will prefer scaling down a larger original image to scaling up a smaller original image.<br><br></li> |
| |
| <li>Go back and repeat steps 2, 3, and 4 until only one choice remains. In the example, screen orientation is the next qualifier in the table for which we have any matches. |
| Eliminate resources that do not specify a screen orientation. </p> |
| <pre><strike>MyApp/res/drawable-en/</strike> |
| MyApp/res/drawable-en-port/ |
| <strike>MyApp/res/drawable-en-notouch-12key/</strike></pre> |
| Only one choice remains, so that's it. When drawables are called for in this |
| example application, the Android system will load resources from the |
| <code>MyApp/res/drawable-en-port/</code> directory. In addition, if the |
| resource being loaded is a bitmap, it will be scaled up so that its supplied |
| low density matches the device's medium density. |
| </ol> |
| <p class="note"><strong>Tip:</strong> The <em>precedence</em> of the qualifiers is more important than the number of qualifiers that exactly match the device. For example, in step 4 above, the last choice on the list includes three qualifiers that exactly match the device (orientation, touchscreen type, and input method), while <code>drawable-en</code> has only one parameter that matches (language). However, language has a higher precedence, so <code>drawable-port-notouch-12key</code> is out.</p> |
| <p>This flowchart summarizes how Android selects resource directories to load.</p> |
| <p><img src="../../../images/resources/res-selection-flowchart.png" alt="resource-selection" width="461" height="471" style="margin:15px"></p> |
| <h3>Terminology</h3> |
| <p>The resource system brings a number of different pieces together to |
| form the final complete resource functionality. To help understand the |
| overall system, here are some brief definitions of the core concepts and |
| components you will encounter in using it:</p> |
| |
| <p><strong>Asset</strong>: A single blob of data associated with an application. This |
| includes object files compiled from the Java source code, graphics (such as PNG |
| images), XML files, etc. These files are organized in a directory hierarchy |
| that, during final packaging of the application, is bundled together into a |
| single ZIP file.</p> |
| |
| <p><strong>aapt</strong>: Android Asset Packaging Tool. The tool that generates the |
| final ZIP file of application assets. In addition to collecting raw assets |
| together, it also parses resource definitions into binary asset data.</p> |
| |
| <p><strong>Resource Table</strong>: A special asset that aapt generates for you, |
| describing all of the resources contained in an application/package. |
| This file is accessed for you by the Resources class; it is not touched |
| directly by applications.</p> |
| |
| <p><strong>Resource</strong>: An entry in the Resource Table describing a single |
| named value. Broadly, there are two types of resources: primitives and |
| bags.</p> |
| |
| <p><strong>Resource Identifier</strong>: In the Resource Table all resources are |
| identified by a unique integer number. In source code (resource descriptions, |
| XML files, Java source code) you can use symbolic names that stand as constants for |
| the actual resource identifier integer.</p> |
| |
| <p><strong>Primitive Resource</strong>: All primitive resources can be written as a |
| simple string, using formatting to describe a variety of primitive types |
| included in the resource system: integers, colors, strings, references to |
| other resources, etc. Complex resources, such as bitmaps and XML |
| describes, are stored as a primitive string resource whose value is the path |
| of the underlying Asset holding its actual data.</p> |
| |
| <p><strong>Bag Resource</strong>: A special kind of resource entry that, instead of a |
| simple string, holds an arbitrary list of name/value pairs. Each name is |
| itself a resource identifier, and each value can hold |
| the same kinds of string formatted data as a normal resource. Bags also |
| support inheritance: a bag can inherit the values from another bag, selectively |
| replacing or extending them to generate its own contents.</p> |
| |
| <p><strong>Kind</strong>: The resource kind is a way to organize resource identifiers |
| for various purposes. For example, drawable resources are used to |
| instantiate Drawable objects, so their data is a primitive resource containing |
| either a color constant or string path to a bitmap or XML asset. Other |
| common resource kinds are string (localized string primitives), color |
| (color primitives), layout (a string path to an XML asset describing a view |
| layout), and style (a bag resource describing user interface attributes). |
| There is also a standard "attr" resource kind, which defines the resource |
| identifiers to be used for naming bag items and XML attributes</p> |
| |
| <p><strong>Style</strong>: The name of the resource kind containing bags that are used |
| to supply a set of user interface attributes. For example, a TextView class may |
| be given a style resource that defines its text size, color, and alignment. |
| In a layout XML file, you associate a style with a bag using the "style" |
| attribute, whose value is the name of the style resource.</p> |
| |
| <p><strong>Style Class</strong>: Specifies a related set of attribute resources. |
| This data is not placed in the resource table itself, but used to generate |
| constants in the source code that make it easier for you to retrieve values out of |
| a style resource and/or XML tag's attributes. For example, the |
| Android platform defines a "View" style class that |
| contains all of the standard view attributes: padding, visibility, |
| background, etc.; when View is inflated it uses this style class to |
| retrieve those values from the XML file (at which point style and theme |
| information is applied as approriate) and load them into its instance.</p> |
| |
| <p><strong>Configuration</strong>: For any particular resource identifier, there may be |
| multiple different available values depending on the current configuration. |
| The configuration includes the locale (language and country), screen |
| orientation, etc. The current configuration is used to |
| select which resource values are in effect when the resource table is |
| loaded.</p> |
| |
| <p><strong>Theme</strong>: A standard style resource that supplies global |
| attribute values for a particular context. For example, when writing an |
| Activity the application developer can select a standard theme to use, such |
| as the Theme.White or Theme.Black styles; this style supplies information |
| such as the screen background image/color, default text color, button style, |
| text editor style, text size, etc. When inflating a layout resource, most |
| values for widgets (the text color, selector, background) if not explicitly |
| set will come from the current theme; style and attribute |
| values supplied in the layout can also assign their value from explicitly |
| named values in the theme attributes if desired.</p> |
| |
| <p><strong>Overlay</strong>: A resource table that does not define a new set of resources, |
| but instead replaces the values of resources that are in another resource table. |
| Like a configuration, this is applied at load time |
| to the resource data; it can add new configuration values (for example |
| strings in a new locale), replace existing values (for example change |
| the standard white background image to a "Hello Kitty" background image), |
| and modify resource bags (for example change the font size of the Theme.White |
| style to have an 18 pt font size). This is the facility that allows the |
| user to select between different global appearances of their device, or |
| download files with new appearances.</p> |
| |
| <h2>Resource Reference</h2> |
| <p>The <a href="available-resources.html">Available Resources</a> |
| document provides a detailed list of the various types of resource and how to use them |
| from within the Java source code, or from other references.</p> |
| |
| <a name="i18n" id="i18n"></a> |
| <h2>Internationalization and Localization</h2> |
| <p class="note"><strong>Coming Soon:</strong> Internationalization and Localization are |
| critical, but are also not quite ready yet in the current SDK. As the |
| SDK matures, this section will contain information on the Internationalization |
| and Localization features of the Android platform. In the meantime, it is a good |
| idea to start by externalizing all strings, and practicing good structure in |
| creating and using resources.</p> |