1 page.title=App Widgets 2 @jd:body 3 4 <div id="qv-wrapper"> 5 <div id="qv"> 6 <h2>Key classes</h2> 7 <ol> 8 <li>{@link android.appwidget.AppWidgetProvider}</li> 9 <li>{@link android.appwidget.AppWidgetProviderInfo}</li> 10 <li>{@link android.appwidget.AppWidgetManager}</li> 11 </ol> 12 <h2>In this document</h2> 13 <ol> 14 <li><a href="#Basics">The Basics</a></li> 15 <li><a href="#Manifest">Declaring an App Widget in the Manifest</a></li> 16 <li><a href="#MetaData">Adding the AppWidgetProviderInfo Metadata</a></li> 17 <li><a href="#CreatingLayout">Creating the App Widget Layout</a></li> 18 <li><a href="#AppWidgetProvider">Using the AppWidgetProvider Class</a> 19 <ol> 20 <li><a href="#ProviderBroadcasts">Receiving App Widget broadcast Intents</a></li> 21 </ol> 22 </li> 23 <li><a href="#Configuring">Creating an App Widget Configuration Activity</a> 24 <ol> 25 <li><a href="#UpdatingFromTheConfiguration">Updating the App Widget from 26 the configuration Activity</a></li> 27 </ol> 28 </li> 29 </ol> 30 31 <h2>See also</h2> 32 <ol> 33 <li><a href="{@docRoot}guide/practices/ui_guidelines/widget_design.html">App Widget Design 34 Guidelines</a></li> 35 <li><a href="http://android-developers.blogspot.com/2009/04/introducing-home-screen-widgets-and.html">Introducing 36 home screen widgets and the AppWidget framework »</a></li> 37 </ol> 38 </div> 39 </div> 40 41 42 <p>App Widgets are miniature application views that can be embedded in other applications 43 (such as the Home screen) and receive periodic updates. These views are referred 44 to as Widgets in the user interface, 45 and you can publish one with an App Widget provider. An application component that is 46 able to hold other App Widgets is called an App Widget host. The screenshot below shows 47 the Music App Widget.</p> 48 49 <img src="{@docRoot}images/appwidget.png" alt="" /> 50 51 <p>This document describes how to publish an App Widget using an App Widget provider.</p> 52 53 54 <h2 id="Basics">The Basics</h2> 55 56 <p>To create an App Widget, you need the following:</p> 57 58 <dl> 59 <dt>{@link android.appwidget.AppWidgetProviderInfo} object</dt> 60 <dd>Describes the metadata for an App Widget, such as the App Widget's layout, update frequency, 61 and the AppWidgetProvider class. This should be defined in XML.</dd> 62 <dt>{@link android.appwidget.AppWidgetProvider} class implementation</dt> 63 <dd>Defines the basic methods that allow you to programmatically interface with the App Widget, 64 based on broadcast events. Through it, you will receive broadcasts when the App Widget is updated, 65 enabled, disabled and deleted.</dd> 66 <dt>View layout</dt> 67 <dd>Defines the initial layout for the App Widget, defined in XML.</dd> 68 </dl> 69 70 <p>Additionally, you can implement an App Widget configuration Activity. This is an optional 71 {@link android.app.Activity} that launches when the user adds your App Widget and allows him or her 72 to modify App Widget settings at create-time.</p> 73 74 <p>The following sections describe how to setup each of these components.</p> 75 76 77 <h2 id="Manifest">Declaring an App Widget in the Manifest</h2> 78 79 <p>First, declare the {@link android.appwidget.AppWidgetProvider} class in your application's 80 <code>AndroidManifest.xml</code> file. For example:</p> 81 82 <pre> 83 <receiver android:name="ExampleAppWidgetProvider" > 84 <intent-filter> 85 <action android:name="android.appwidget.action.APPWIDGET_UPDATE" /> 86 </intent-filter> 87 <meta-data android:name="android.appwidget.provider" 88 android:resource="@xml/example_appwidget_info" /> 89 </receiver> 90 </pre> 91 92 <p>The <code><receiver></code> element requires the <code>android:name</code> 93 attribute, which specifies the {@link android.appwidget.AppWidgetProvider} used 94 by the App Widget.</p> 95 96 <p>The <code><intent-filter></code> element must include an <code><action></code> 97 element with the <code>android:name</code> attribute. This attribute specifies 98 that the {@link android.appwidget.AppWidgetProvider} accepts the {@link 99 android.appwidget.AppWidgetManager#ACTION_APPWIDGET_UPDATE ACTION_APPWIDGET_UPDATE} broadcast. 100 This is the only broadcast that you must explicitly declare. The {@link android.appwidget.AppWidgetManager} 101 automatically sends all other App Widget broadcasts to the AppWidgetProvider as necessary.</p> 102 103 <p>The <code><meta-data></code> element specifies the 104 {@link android.appwidget.AppWidgetProviderInfo} resource and requires the 105 following attributes:</p> 106 <ul> 107 <li><code>android:name</code> - Specifies the metadata name. Use <code>android.appwidget.provider</code> 108 to identify the data as the {@link android.appwidget.AppWidgetProviderInfo} descriptor.</li> 109 <li><code>android:resource</code> - Specifies the {@link android.appwidget.AppWidgetProviderInfo} 110 resource location.</li> 111 </ul> 112 113 114 <h2 id="MetaData">Adding the AppWidgetProviderInfo Metadata</h2> 115 116 <p>The {@link android.appwidget.AppWidgetProviderInfo} defines the essential 117 qualities of an App Widget, such as its minimum layout dimensions, its initial layout resource, 118 how often to update the App Widget, and (optionally) a configuration Activity to launch at create-time. 119 Define the AppWidgetProviderInfo object in an XML resource using a single 120 <code><appwidget-provider></code> element and save it in the project's <code>res/xml/</code> 121 folder.</p> 122 123 <p>For example:</p> 124 125 <pre> 126 <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" 127 android:minWidth="294dp" 128 android:minHeight="72dp" 129 android:updatePeriodMillis="86400000" 130 android:initialLayout="@layout/example_appwidget" 131 android:configure="com.example.android.ExampleAppWidgetConfigure" > 132 </appwidget-provider> 133 </pre> 134 135 <p>Here's a summary of the <code><appwidget-provider></code> attributes:</p> 136 <ul> 137 <li>The values for the <code>minWidth</code> and <code>minHeight</code> attributes specify the minimum 138 area required by the App Widget's layout. 139 <p>The default Home screen positions App Widgets in its window based on a grid of 140 cells that have a defined height and width. If the values for an App Widget's minimum width 141 or height don't match the dimensions of the cells, 142 then the App Widget dimensions round <em>up</em> to the nearest cell size. 143 (See the <a href="{@docRoot}guide/practices/ui_guidelines/widget_design.html">App Widget Design 144 Guidelines</a> for more information on the Home screen cell sizes.)</p> 145 <p>Because the Home screen's layout orientation (and thus, the cell sizes) can change, 146 as a rule of thumb, you should assume the worst-case cell size of 74 pixels for the height 147 <em>and</em> width of a cell. However, you must subtract 2 from the final dimension to account 148 for any integer rounding errors that occur in the pixel count. To find your minimum width 149 and height in density-independent pixels (dp), use this formula:<br/> 150 <code>(number of cells * 74) - 2</code><br/> 151 Following this formula, you should use 72 dp for a height of one cell, 294 dp and for a width of four cells.</p> 152 </li> 153 <li>The <code>updatePeriodMillis</code> attribute defines how often the App Widget framework should 154 request an update from the {@link android.appwidget.AppWidgetProvider} by calling the 155 {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 156 onUpdate()} method. The actual update is not guaranteed to occur exactly on time with this value 157 and we suggest updating as infrequently as possible—perhaps no more than once an hour to 158 conserve the battery. You might also allow the user to adjust the frequency in a 159 configuration—some people might want a stock ticker to update every 15 minutes, or maybe 160 only four times a day. 161 <p class="note"><strong>Note:</strong> If the device is asleep when it is time for an update 162 (as defined by <code>updatePeriodMillis</code>), then the device will wake up in order 163 to perform the update. If you don't update more than once per hour, this probably won't 164 cause significant problems for the battery life. If, however, you need to update more 165 frequently and/or you do not need to update while the device is asleep, then you can instead 166 perform updates based on an alarm that will not wake the device. To do so, set an alarm with 167 an Intent that your AppWidgetProvider receives, using the {@link android.app.AlarmManager}. 168 Set the alarm type to either {@link android.app.AlarmManager#ELAPSED_REALTIME} or 169 {@link android.app.AlarmManager#RTC}, which will only 170 deliver the alarm when the device is awake. Then set <code>updatePeriodMillis</code> to 171 zero (<code>"0"</code>).</p> 172 </li> 173 <li>The <code>initialLayout</code> attribute points to the layout resource that defines the 174 App Widget layout.</li> 175 <li>The <code>configure</code> attribute defines the {@link android.app.Activity} to launch when 176 the user adds the App Widget, in order for him or her to configure App Widget properties. This is optional 177 (read <a href="#Configuring">Creating an App Widget Configuration Activity</a> below).</li> 178 </ul> 179 180 <p>See the {@link android.appwidget.AppWidgetProviderInfo} class for more information on the 181 attributes accepted by the <code><appwidget-provider></code> element.</p> 182 183 184 <h2 id="CreatingLayout">Creating the App Widget Layout</h2> 185 186 <p>You must define an initial layout for your App Widget in XML and save it in the project's 187 <code>res/layout/</code> directory. You can design your App Widget using the View objects listed 188 below, but before you begin designing your App Widget, please read and understand the 189 <a href="{@docRoot}guide/practices/ui_guidelines/widget_design.html">App Widget Design 190 Guidelines</a>.</p> 191 192 <p>Creating the App Widget layout is simple if you're 193 familiar with <a href="{@docRoot}guide/topics/ui/declaring-layout.html">Declaring Layout in XML</a>. 194 However, you must be aware that App Widget layouts are based on {@link android.widget.RemoteViews}, 195 which do not support every kind of layout or view widget.</p> 196 197 <p>A RemoteViews object (and, consequently, an App Widget) can support the 198 following layout classes:</p> 199 200 <ul class="nolist"> 201 <li>{@link android.widget.FrameLayout}</li> 202 <li>{@link android.widget.LinearLayout}</li> 203 <li>{@link android.widget.RelativeLayout}</li> 204 </ul> 205 206 <p>And the following widget classes:</p> 207 <ul class="nolist"> 208 <li>{@link android.widget.AnalogClock}</li> 209 <li>{@link android.widget.Button}</li> 210 <li>{@link android.widget.Chronometer}</li> 211 <li>{@link android.widget.ImageButton}</li> 212 <li>{@link android.widget.ImageView}</li> 213 <li>{@link android.widget.ProgressBar}</li> 214 <li>{@link android.widget.TextView}</li> 215 </ul> 216 217 <p>Descendants of these classes are not supported.</p> 218 219 220 <h2 id="AppWidgetProvider">Using the AppWidgetProvider Class</h2> 221 222 <div class="sidebox-wrapper"> 223 <div class="sidebox"> 224 <p>You must declare your AppWidgetProvider class implementation as a broadcast receiver 225 using the <code><receiver></code> element in the AndroidManifest (see 226 <a href="#Manifest">Declaring an App Widget in the Manifest</a> above).</p> 227 </div> 228 </div> 229 230 <p>The {@link android.appwidget.AppWidgetProvider} class extends BroadcastReceiver as a convenience 231 class to handle the App Widget broadcasts. The AppWidgetProvider receives only the event broadcasts that 232 are relevant to the App Widget, such as when the App Widget is updated, deleted, enabled, and disabled. 233 When these broadcast events occur, the AppWidgetProvider receives the following method calls:</p> 234 235 <dl> 236 <dt>{@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[])}</dt> 237 <dd>This is called to update the App Widget at intervals defined by the <code>updatePeriodMillis</code> 238 attribute in the AppWidgetProviderInfo (see <a href="#MetaData">Adding the 239 AppWidgetProviderInfo Metadata</a> above). This method is also called 240 when the user adds the App Widget, so it should perform the essential setup, 241 such as define event handlers for Views and start a temporary 242 {@link android.app.Service}, if necessary. However, if you have declared a configuration 243 Activity, <strong>this method is not called</strong> when the user adds the App Widget, 244 but is called for the subsequent updates. It is the responsibility of the 245 configuration Activity to perform the first update when configuration is done. 246 (See <a href="#Configuring">Creating an App Widget Configuration Activity</a> below.)</dd> 247 <dt>{@link android.appwidget.AppWidgetProvider#onDeleted(Context,int[])}</dt> 248 <dd>This is called every time an App Widget is deleted from the App Widget host.</dd> 249 <dt>{@link android.appwidget.AppWidgetProvider#onEnabled(Context)}</dt> 250 <dd>This is called when an instance the App Widget is created for the first time. For example, if the user 251 adds two instances of your App Widget, this is only called the first time. 252 If you need to open a new database or perform other setup that only needs to occur once 253 for all App Widget instances, then this is a good place to do it.</dd> 254 <dt>{@link android.appwidget.AppWidgetProvider#onDisabled(Context)}</dt> 255 <dd>This is called when the last instance of your App Widget is deleted from the App Widget host. 256 This is where you should clean up any work done in 257 {@link android.appwidget.AppWidgetProvider#onEnabled(Context)}, 258 such as delete a temporary database.</dd> 259 <dt>{@link android.appwidget.AppWidgetProvider#onReceive(Context,Intent)}</dt> 260 <dd>This is called for every broadcast and before each of the above callback methods. 261 You normally don't need to implement this method because the default AppWidgetProvider 262 implementation filters all App Widget broadcasts and calls the above 263 methods as appropriate.</dd> 264 </dl> 265 266 <p class="warning"><strong>Note:</strong> In Android 1.5, there is a known issue in which the 267 <code>onDeleted()</code> method will not be called when it should be. To work around this issue, 268 you can implement {@link android.appwidget.AppWidgetProvider#onReceive(Context,Intent) 269 onReceive()} as described in this 270 <a href="http://groups.google.com/group/android-developers/msg/e405ca19df2170e2">Group post</a> 271 to receive the <code>onDeleted()</code> callback. 272 </p> 273 274 <p>The most important AppWidgetProvider callback is 275 {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 276 onUpdated()} because it is called when each App Widget is added to a host (unless you use 277 a configuration Activity). If your App Widget accepts any 278 user interaction events, then you need to register the event handlers in this callback. 279 If your App Widget doesn't create temporary 280 files or databases, or perform other work that requires clean-up, then 281 {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 282 onUpdated()} may be the only callback method you need to define. For example, if you want an App Widget 283 with a button that launches an Activity when clicked, you could use the following 284 implementation of AppWidgetProvider:</p> 285 286 <pre> 287 public class ExampleAppWidgetProvider extends AppWidgetProvider { 288 289 public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) { 290 final int N = appWidgetIds.length; 291 292 // Perform this loop procedure for each App Widget that belongs to this provider 293 for (int i=0; i<N; i++) { 294 int appWidgetId = appWidgetIds[i]; 295 296 // Create an Intent to launch ExampleActivity 297 Intent intent = new Intent(context, ExampleActivity.class); 298 PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0); 299 300 // Get the layout for the App Widget and attach an on-click listener to the button 301 RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.appwidget_provider_layout); 302 views.setOnClickPendingIntent(R.id.button, pendingIntent); 303 304 // Tell the AppWidgetManager to perform an update on the current App Widget 305 appWidgetManager.updateAppWidget(appWidgetId, views); 306 } 307 } 308 } 309 </pre> 310 311 <p>This AppWidgetProvider defines only the 312 {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 313 onUpdated()} method for the purpose 314 of defining a {@link android.app.PendingIntent} that launches an {@link android.app.Activity} 315 and attaching it to the App Widget's button 316 with {@link android.widget.RemoteViews#setOnClickPendingIntent(int,PendingIntent)}. 317 Notice that it includes a loop that iterates through each entry in <code>appWidgetIds</code>, which 318 is an array of IDs that identify each App Widget created by this provider. 319 In this way, if the user creates more than one instance of the App Widget, then they are 320 all updated simultaneously. However, only one <code>updatePeriodMillis</code> schedule will be 321 managed for all instances of the App Widget. For example, if the update schedule is defined 322 to be every two hours, and a second instance 323 of the App Widget is added one hour after the first one, then they will both be updated 324 on the period defined by the first one and the second update period will be ignored 325 (they'll both be updated every two hours, not every hour).</p> 326 327 <p class="note"><strong>Note:</strong> Because the AppWidgetProvider is a BroadcastReceiver, 328 your process is not guaranteed to keep running after the callback methods return (see 329 <a href="{@docRoot}guide/topics/fundamentals.html#broadlife">Application Fundamentals > 330 Broadcast Receiver Lifecycle</a> for more information). If your App Widget setup process can take several 331 seconds (perhaps while performing web requests) and you require that your process continues, 332 consider starting a {@link android.app.Service} 333 in the {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 334 onUpdated()} method. From within the Service, you can perform your own updates to the App Widget 335 without worrying about the AppWidgetProvider closing down due to an 336 <a href="{@docRoot}guide/practices/design/responsiveness.html">Application Not Responding</a> 337 (ANR) error. See the 338 <a href="http://code.google.com/p/wiktionary-android/source/browse/trunk/Wiktionary/src/com/example/android/wiktionary/WordWidget.java">Wiktionary 339 sample's AppWidgetProvider</a> for an example of an App Widget running a {@link android.app.Service}.</p> 340 341 <p>Also see the <a 342 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/appwidget/ExampleAppWidgetProvider.html"> 343 ExampleAppWidgetProvider.java</a> sample class.</p> 344 345 346 <h3 id="ProviderBroadcasts">Receiving App Widget broadcast Intents</h3> 347 348 <p>{@link android.appwidget.AppWidgetProvider} is just a convenience class. If you would like 349 to receive the App Widget broadcasts directly, you can implement your own 350 {@link android.content.BroadcastReceiver} or override the 351 {@link android.appwidget.AppWidgetProvider#onReceive(Context,Intent)} callback. 352 The four Intents you need to care about are:</p> 353 <ul> 354 <li>{@link android.appwidget.AppWidgetManager#ACTION_APPWIDGET_UPDATE}</li> 355 <li>{@link android.appwidget.AppWidgetManager#ACTION_APPWIDGET_DELETED}</li> 356 <li>{@link android.appwidget.AppWidgetManager#ACTION_APPWIDGET_ENABLED}</li> 357 <li>{@link android.appwidget.AppWidgetManager#ACTION_APPWIDGET_DISABLED}</li> 358 </ul> 359 360 361 362 <h2 id="Configuring">Creating an App Widget Configuration Activity</h2> 363 364 <p>If you would like the user to configure settings when he or she adds a new App Widget, 365 you can create an App Widget configuration Activity. This {@link android.app.Activity} 366 will be automatically launched by the App Widget host and allows the user to configure 367 available settings for the App Widget at create-time, such as the App Widget color, size, 368 update period or other functionality settings.</p> 369 370 <p>The configuration Activity should be declared as a normal Activity in the Android manifest file. 371 However, it will be launched by the App Widget host with the {@link 372 android.appwidget.AppWidgetManager#ACTION_APPWIDGET_CONFIGURE ACTION_APPWIDGET_CONFIGURE} action, 373 so the Activity needs to accept this Intent. For example:</p> 374 375 <pre> 376 <activity android:name=".ExampleAppWidgetConfigure"> 377 <intent-filter> 378 <action android:name="android.appwidget.action.APPWIDGET_CONFIGURE" /> 379 </intent-filter> 380 </activity> 381 </pre> 382 383 <p>Also, the Activity must be declared in the AppWidgetProviderInfo XML file, with the 384 <code>android:configure</code> attribute (see <a href="#MetaData">Adding 385 the AppWidgetProviderInfo Metadata</a> above). For example, the configuration Activity 386 can be declared like this:</p> 387 388 <pre> 389 <appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android" 390 ... 391 android:configure="com.example.android.ExampleAppWidgetConfigure" 392 ... > 393 </appwidget-provider> 394 </pre> 395 396 <p>Notice that the Activity is declared with a fully-qualified namespace, because 397 it will be referenced from outside your package scope.</p> 398 399 <p>That's all you need to get started with a configuration Activity. Now all you need is the actual 400 Activity. There are, however, two important things to remember when you implement the Activity:</p> 401 <ul> 402 <li>The App Widget host calls the configuration Activity and the configuration Activity should always 403 return a result. The result should include the App Widget ID 404 passed by the Intent that launched the Activity (saved in the Intent extras as 405 {@link android.appwidget.AppWidgetManager#EXTRA_APPWIDGET_ID}).</li> 406 <li>The {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 407 onUpdate()} method <strong>will not be called</strong> when the App Widget is created 408 (the system will not send the ACTION_APPWIDGET_UPDATE broadcast when a configuration Activity 409 is launched). It is the responsibility of the configuration Activity to request an update from the 410 AppWidgetManager when the App Widget is first created. However, 411 {@link android.appwidget.AppWidgetProvider#onUpdate(Context,AppWidgetManager,int[]) 412 onUpdate()} will be called for subsequent updates—it is only skipped the first time.</li> 413 </ul> 414 415 <p>See the code snippets in the following section for an example of how to return a result 416 from the configuration and update the App Widget.</p> 417 418 419 <h3 id="UpdatingFromTheConfiguration">Updating the App Widget from the configuration Activity</h3> 420 421 <p>When an App Widget uses a configuration Activity, it is the responsibility of the Activity 422 to update the App Widget when configuration is complete. 423 You can do so by requesting an update directly from the 424 {@link android.appwidget.AppWidgetManager}.</p> 425 426 <p>Here's a summary of the procedure to properly update the App Widget and close 427 the configuration Activity:</p> 428 429 <ol> 430 <li>First, get the App Widget ID from the Intent that launched the Activity: 431 <pre> 432 Intent intent = getIntent(); 433 Bundle extras = intent.getExtras(); 434 if (extras != null) { 435 mAppWidgetId = extras.getInt( 436 AppWidgetManager.EXTRA_APPWIDGET_ID, 437 AppWidgetManager.INVALID_APPWIDGET_ID); 438 } 439 </pre> 440 </li> 441 <li>Perform your App Widget configuration.</li> 442 <li>When the configuration is complete, get an instance of the AppWidgetManager by calling 443 {@link android.appwidget.AppWidgetManager#getInstance(Context)}: 444 <pre> 445 AppWidgetManager appWidgetManager = AppWidgetManager.getInstance(context); 446 </pre> 447 </li> 448 <li>Update the App Widget with a {@link android.widget.RemoteViews} layout by calling 449 {@link android.appwidget.AppWidgetManager#updateAppWidget(int,RemoteViews)}: 450 <pre> 451 RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.example_appwidget); 452 appWidgetManager.updateAppWidget(mAppWidgetId, views); 453 </pre> 454 </li> 455 <li>Finally, create the return Intent, set it with the Activity result, and finish the Activity:</li> 456 <pre> 457 Intent resultValue = new Intent(); 458 resultValue.putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, mAppWidgetId); 459 setResult(RESULT_OK, resultValue); 460 finish(); 461 </pre> 462 </li> 463 </ol> 464 465 <p class="note"><strong>Tip:</strong> When your configuration Activity first opens, set 466 the Activity result to RESULT_CANCELED. This way, if the user backs-out of the Activity before 467 reaching the end, the App Widget host is notified that the configuration was cancelled and the 468 App Widget will not be added.</p> 469 470 <p>See the <a 471 href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/appwidget/ExampleAppWidgetConfigure.html"> 472 ExampleAppWidgetConfigure.java</a> sample class in ApiDemos for an example.</p> 473 474 475 476
