1 page.title=Android 4.1 APIs 2 excludeFromSuggestions=true 3 sdk.platform.version=4.1 4 sdk.platform.apiLevel=16 5 @jd:body 6 7 <div id="qv-wrapper"> 8 <div id="qv"> 9 10 <h2>In this document 11 <a href="#" onclick="hideNestedItems('#toc41',this);return false;" class="header-toggle"> 12 <span class="more">show more</span> 13 <span class="less" style="display:none">show less</span></a></h2> 14 15 <ol id="toc41" class="hide-nested"> 16 <li><a href="#AppComponents">App Components</a> 17 <ol> 18 <li><a href="#Isolated">Isolated services</a></li> 19 <li><a href="#Memory">Memory management</a></li> 20 <li><a href="#ContentProvider">Content providers</a></li> 21 <li><a href="#LiveWallpapers">Live Wallpapers</a></li> 22 <li><a href="#StackNav">App stack navigation</a></li> 23 </ol> 24 </li> 25 <li><a href="#Multimedia">Multimedia</a> 26 <ol> 27 <li><a href="#Codecs">Media codecs</a></li> 28 <li><a href="#AudioCue">Record audio on cue</a></li> 29 <li><a href="#TextTracks">Timed text tracks</a></li> 30 <li><a href="#AudioEffects">Audio effects</a></li> 31 <li><a href="#Gapless">Gapless playback</a></li> 32 </ol> 33 </li> 34 <li><a href="#Camera">Camera</a> 35 <ol> 36 <li><a href="#AutoFocus">Auto focus movement</a></li> 37 <li><a href="#CameraSounds">Camera sounds</a></li> 38 </ol> 39 </li> 40 <li><a href="#Connectivity">Connectivity</a> 41 <ol> 42 <li><a href="#AndroidBeam">Android Beam</a></li> 43 <li><a href="#LocalNsd">Network service discovery</a></li> 44 <li><a href="#WiFiNsd">Wi-Fi P2P service discovery</a></li> 45 <li><a href="#NetworkUsage">Network usage</a></li> 46 </ol> 47 </li> 48 <li><a href="#A11y">Accessibility</a> 49 <ol> 50 <li><a href="#A11yService">Accessibility service APIs</a></li> 51 <li><a href="#A11yCustomNav">Customizable app navigation</a></li> 52 <li><a href="#A11yStructure">More accessible widgets</a></li> 53 </ol> 54 </li> 55 <li><a href="#CopyPaste">Copy and Paste</a> 56 <ol> 57 <li><a href="#CopyIntent">Copy and paste with intents</a></li> 58 </ol> 59 </li> 60 <li><a href="#Renderscript">Renderscript</a></li> 61 <li><a href="#Animation">Animation</a> 62 <ol> 63 <li><a href="#ActivityOptions">Activity launch animations</a></li> 64 <li><a href="#TimeAnimator">Time animator</a></li> 65 </ol> 66 </li> 67 <li><a href="#UI">User Interface</a> 68 <ol> 69 <li><a href="#Notifications">Notifications</a></li> 70 <li><a href="#SystemUI">Controls for system UI</a></li> 71 <li><a href="#RemoteViews">Remote views</a></li> 72 <li><a href="#Fonts">Font families</a></li> 73 </ol> 74 </li> 75 <li><a href="#Input">Input Framework</a> 76 <ol> 77 <li><a href="#InputDevice">Multiple input devices</a></li> 78 <li><a href="#Vibrate">Vibrate for input controllers</a></li> 79 </ol> 80 </li> 81 <li><a href="#Permissions">Permissions</a></li> 82 <li><a href="#DeviceFeatures">Device Features</a></li> 83 </ol> 84 85 <h2>See also</h2> 86 <ol> 87 <li><a 88 href="{@docRoot}sdk/api_diff/16/changes.html">API 89 Differences Report »</a> </li> 90 </ol> 91 92 </div> 93 </div> 94 95 96 <p>API Level: 16</p> 97 98 <p>Android 4.1 ({@link android.os.Build.VERSION_CODES#JELLY_BEAN}) 99 is a progression of the platform that offers improved 100 performance and enhanced user experience. It adds new features for users and app 101 developers. This document provides an introduction to the most notable and 102 useful new APIs for app developers.</p> 103 104 105 <div class="sidebox-wrapper"> 106 <div class="sidebox"> 107 108 <h3 id="ApiLevel">Declare your app API Level</h3> 109 110 <p>To better optimize your app for devices running Android {@sdkPlatformVersion}, 111 you should set your <a 112 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code targetSdkVersion}</a> to 113 <code>"{@sdkPlatformApiLevel}"</code>, install it on an Android {@sdkPlatformVersion} system image, 114 test it, then publish an update with this change.</p> 115 116 <p>You 117 can use APIs in Android {@sdkPlatformVersion} while also supporting older versions by adding 118 conditions to your code that check for the system API level before executing 119 APIs not supported by your <a 120 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code minSdkVersion}</a>. 121 To learn more about 122 maintaining backward-compatibility, read <a 123 href="{@docRoot}training/backward-compatible-ui/index.html">Creating Backward-Compatible 124 UIs</a>.</p> 125 126 <p>More information about how API levels work is available in <a 127 href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#ApiLevels">What is API 128 Level?</a></p> 129 130 </div> 131 </div> 132 133 134 135 <p>As an app developer, Android 4.1 is available to you from the 136 <a href="{@docRoot}tools/help/sdk-manager.html">SDK Manager</a> as a system image you can 137 run in the Android emulator and an SDK platform against which you can build your app. You should 138 download the system image and platform as soon as possible to build and test your 139 app on Android 4.1.</p> 140 141 142 143 144 145 <h2 id="AppComponents">App Components</h2> 146 147 148 149 <h3 id="Isolated">Isolated services</h3> 150 151 <p>By specifying <a href="{@docRoot}guide/topics/manifest/service-element.html#isolated">{@code android:isolatedProcess="true"}</a> in the 152 <a href="{@docRoot}guide/topics/manifest/service-element.html">{@code <service>}</a> tag, your {@link android.app.Service} will run under 153 its own isolated user ID process that has no permissions of its own.</p> 154 155 156 <h3 id="Memory">Memory management</h3> 157 158 <p>New {@link android.content.ComponentCallbacks2} constants such as {@link 159 android.content.ComponentCallbacks2#TRIM_MEMORY_RUNNING_LOW} and {@link 160 android.content.ComponentCallbacks2#TRIM_MEMORY_RUNNING_CRITICAL} provide foreground 161 processes more information about 162 memory state before the system calls {@link android.app.Activity#onLowMemory()}.</p> 163 164 <p>New {@link android.app.ActivityManager#getMyMemoryState} method allows you to 165 retrieve the general memory state.</p> 166 167 168 <h3 id="ContentProvider">Content providers</h3> 169 170 <p>A new method, {@link android.content.ContentResolver#acquireUnstableContentProviderClient 171 acquireUnstableContentProviderClient()}, allows you to access a {@link 172 android.content.ContentProviderClient} that may be "unstable" such that your app will not crash if 173 the content provider does. It's useful when you are interacting with content providers in a separate 174 app.</p> 175 176 177 178 <h3 id="LiveWallpapers">Live Wallpapers</h3> 179 180 <p>New intent protocol to directly launch the live wallpaper preview activity so you can help 181 users easily select your live wallpaper without forcing them to leave 182 your app and navigate through the Home wallpaper picker.</p> 183 184 <p>To launch the live wallpaper picker, call {@link android.content.Context#startActivity 185 startActivity()} with an {@link android.content.Intent} using 186 {@link android.app.WallpaperManager#ACTION_CHANGE_LIVE_WALLPAPER} and an extra 187 that specifies your live wallpaper {@link android.content.ComponentName} as a string in {@link 188 android.app.WallpaperManager#EXTRA_LIVE_WALLPAPER_COMPONENT}.</p> 189 190 191 192 193 <h3 id="StackNav">App stack navigation</h3> 194 195 <p>Android 4.1 makes it much easier to implement the proper design patterns for Up navigation. 196 All you need to do is add the <a 197 href="{@docRoot}guide/topics/manifest/activity-element.html#parent">{@code 198 android:parentActivityName}</a> to each <a 199 href="{@docRoot}guide/topics/manifest/activity-element.html">{@code <activity>}</a> element in 200 your manifest file. The system uses this information to open the appropriate activity when the user 201 presses the Up button in the action bar (while also finishing the current activity). So if you 202 declare the <a href="{@docRoot}guide/topics/manifest/activity-element.html#parent">{@code 203 android:parentActivityName}</a> for each activity, you don't need the {@link 204 android.app.Activity#onOptionsItemSelected onOptionsItemSelected()} method to handle click 205 events on the action bar's app icon—the system now handles that event and resumes or 206 creates the appropriate activity.</p> 207 208 <p>This is particularly powerful for scenarios in which the user enters one of your app's activities 209 through a "deep dive" intent such as from a notification or an intent from 210 different app (as described in the design guide for <a 211 href="{@docRoot}design/patterns/navigation.html#between-apps">Navigating Between Apps</a>). When 212 the user enters your activity this way, your app may not naturally have a back stack of 213 activities that can be resumed as the user navigates up. However, when you supply the <a 214 href="{@docRoot}guide/topics/manifest/activity-element.html#parent">{@code 215 android:parentActivityName}</a> attribute for your activities, the system recognizes 216 whether or not your app already contains a back stack of parent activities and, if not, constructs 217 a synthetic back stack that contains all parent activities.</p> 218 219 <p class="note"><strong>Note:</strong> When the user enters a deep activity in your app and 220 it creates a new task for your app, the system actually inserts the stack of parent activities 221 into the task. As such, pressing the Back button also navigates back through the stack of parent 222 activities.</p> 223 224 <p>When the system creates a synthetic back stack for your app, it builds a basic {@link 225 android.content.Intent} to create a new instance of each parent activity. So there's no 226 saved state for the parent activities the way you'd expect had the user naturally navigated 227 through 228 each activity. If any of the parent activities normally show a UI that's dependent on 229 the user's context, that context information will be missing and you should deliver it when the 230 user 231 navigates back through the stack. For example, if the user is viewing an album 232 in a music app, navigating up might bring them to an activity that lists all albums in a chosen 233 music genre. In this case, if the stack must be created, it's necessary that you inform the parent 234 activity what genre the current album belongs to so that the parent can display the proper list as 235 if the user actually came from that activity. To deliver such information to a synthetic parent 236 activity, you must override the {@link 237 android.app.Activity#onPrepareNavigateUpTaskStack onPrepareNavigateUpTaskStack()} method. This 238 provides you with a {@link android.app.TaskStackBuilder} object that the system created in order to 239 synthesize the parent activities. The {@link android.app.TaskStackBuilder} contains {@link 240 android.content.Intent} objects that the system uses to create each parent activity. In your 241 implementation of {@link android.app.Activity#onPrepareNavigateUpTaskStack 242 onPrepareNavigateUpTaskStack()}, you can modify the appropriate {@link android.content.Intent} to 243 add extra data that the parent activity can use to determine the appropriate context and display 244 the appropriate UI.</p> 245 246 <p>When the system creates the {@link android.app.TaskStackBuilder}, it adds the {@link 247 android.content.Intent} objects that are used to create the parent activities in their logical 248 order beginning from the top of the activity tree. So, the last {@link 249 android.content.Intent} added to the internal array is the direct parent of the current activity. If 250 you want to modify the {@link android.content.Intent} for the activity's parent, first determine 251 the length of the array with {@link android.app.TaskStackBuilder#getIntentCount()} and pass that 252 value to {@link android.app.TaskStackBuilder#editIntentAt editIntentAt()}.</p> 253 254 <p>If your app structure is more complex, there are several other APIs 255 available that allow you to handle the behavior of Up navigation and 256 fully customize the synthetic back stack. Some of the APIs that give you additional 257 control include:</p> 258 <dl> 259 <dt>{@link android.app.Activity#onNavigateUp}</dt> 260 <dd>Override this to perform a custom action when the user presses the Up button.</dd> 261 <dt>{@link android.app.Activity#navigateUpTo}</dt> 262 <dd>Call this to finish the current activity and go to the activity indicated by the 263 supplied {@link android.content.Intent}. If the activity exists in the back stack, but 264 is not the closest parent, then all other activities between the current activity and the 265 activity specified with the intent are finished as well.</dd> 266 <dt>{@link android.app.Activity#getParentActivityIntent}</dt> 267 <dd>Call this to get the {@link android.content.Intent} that will start the logical 268 parent for the current activity.</dd> 269 <dt>{@link android.app.Activity#shouldUpRecreateTask}</dt> 270 <dd>Call this to query whether a synthetic back stack must be created in order to navigate 271 up. Returns true if a synthetic stack must be created, false if the appropropriate stack 272 already exists.</dd> 273 <dt>{@link android.app.Activity#finishAffinity}</dt> 274 <dd>Call this to finish the current activity and all parent activities with the same 275 task affinity that are chained to the current activity. 276 If you override the default behaviors such as 277 {@link android.app.Activity#onNavigateUp}, you should call this method when you 278 create a synthetic back stack upon Up navigation.</dd> 279 <dt>{@link android.app.Activity#onCreateNavigateUpTaskStack onCreateNavigateUpTaskStack}</dt> 280 <dd>Override this if you need to fully control how the synthetic task stack is created. If you want to simply add some extra data to the intents for your back stack, you should instead override {@link android.app.Activity#onPrepareNavigateUpTaskStack 281 onPrepareNavigateUpTaskStack()}</dd> 282 </dl> 283 284 <p>However, most apps don't need to use these APIs or implement {@link 285 android.app.Activity#onPrepareNavigateUpTaskStack 286 onPrepareNavigateUpTaskStack()}, but can can achieve the correct behavior simply by 287 adding <a 288 href="{@docRoot}guide/topics/manifest/activity-element.html#parent">{@code 289 android:parentActivityName}</a> to each <a 290 href="{@docRoot}guide/topics/manifest/activity-element.html">{@code <activity>}</a> element.</p> 291 292 293 294 295 296 297 298 299 300 301 302 <h2 id="Multimedia">Multimedia</h2> 303 304 <h3 id="Codecs">Media codecs</h3> 305 306 <p>The {@link android.media.MediaCodec} class provides access to low-level media codecs for encoding 307 and decoding your media. You can instantiate a {@link android.media.MediaCodec} by calling {@link 308 android.media.MediaCodec#createEncoderByType createEncoderByType()} to encode media or call {@link 309 android.media.MediaCodec#createDecoderByType createDecoderByType()} to decode media. Each of these 310 methods take a MIME type for the type of media you want to encode or decode, such as {@code 311 "video/3gpp"} or {@code "audio/vorbis"}. </p> 312 313 <p>With an instance of {@link android.media.MediaCodec} created, you can then call {@link 314 android.media.MediaCodec#configure configure()} to specify properties such as the media format or 315 whether or not the content is encrypted.</p> 316 317 <p>Whether you're encoding or decoding your media, the rest of the process is the same after you 318 create the {@link android.media.MediaCodec}. First call {@link 319 android.media.MediaCodec#getInputBuffers()} to get an array of input {@link java.nio.ByteBuffer} 320 objects and {@link android.media.MediaCodec#getOutputBuffers()} to get an array of output {@link 321 java.nio.ByteBuffer} objects.</p> 322 323 <p>When you're ready to encode or decode, call {@link android.media.MediaCodec#dequeueInputBuffer 324 dequeueInputBuffer()} to get the index position of the {@link 325 java.nio.ByteBuffer} (from the array of input buffers) that you should use to to feed in your source 326 media. After you fill the {@link java.nio.ByteBuffer} with your source media, release ownership 327 of the buffer by calling {@link android.media.MediaCodec#queueInputBuffer queueInputBuffer()}.</p> 328 329 <p>Likewise for the output buffer, call {@link android.media.MediaCodec#dequeueOutputBuffer 330 dequeueOutputBuffer()} to get the index position of the {@link java.nio.ByteBuffer} 331 where you'll receive the results. After you read the output from the {@link java.nio.ByteBuffer}, 332 release ownership by calling {@link android.media.MediaCodec#releaseOutputBuffer 333 releaseOutputBuffer()}.</p> 334 335 <p>You can handle encrypted media data in the codecs by calling {@link 336 android.media.MediaCodec#queueSecureInputBuffer queueSecureInputBuffer()} in conjunction with 337 the {@link android.media.MediaCrypto} APIs, instead of the normal {@link 338 android.media.MediaCodec#queueInputBuffer queueInputBuffer()}.</p> 339 340 <p>For more information about how to use codecs, see the {@link android.media.MediaCodec} documentation.</p> 341 342 <!-- 343 <h3 id="Routing">Media routing</h3> 344 345 <p>The new {@link android.media.MediaRouter} class allows you to route media channels and 346 streams from the current device to external speakers and other devices. You 347 can acquire an instance of {@link android.media.MediaRouter} by calling {@link 348 android.content.Context#getSystemService getSystemService(}{@link 349 android.content.Context#MEDIA_ROUTER_SERVICE MEDIA_ROUTER_SERVICE)}.</p> 350 --> 351 352 353 <h3 id="AudioCue">Record audio on cue</h3> 354 355 <p>New method {@link android.media.AudioRecord#startRecording startRecording()} allows 356 you to begin audio recording based on a cue defined by a {@link android.media.MediaSyncEvent}. 357 The {@link android.media.MediaSyncEvent} specifies an audio session 358 (such as one defined by {@link android.media.MediaPlayer}), which when complete, triggers 359 the audio recorder to begin recording. For example, you can use this functionality to 360 play an audio tone that indicates the beginning of a recording session and recording 361 automatically begins so you don't have to manually synchronize the tone and the beginning 362 of recording.</p> 363 364 365 <h3 id="TextTracks">Timed text tracks</h3> 366 367 <p>The {@link android.media.MediaPlayer} now handles both in-band and out-of-band text tracks. 368 In-band text tracks come as a text track within an MP4 or 3GPP media source. Out-of-band text 369 tracks can be added as an external text source via {@link 370 android.media.MediaPlayer#addTimedTextSource addTimedTextSource()} method. After all external text 371 track sources are added, {@link android.media.MediaPlayer#getTrackInfo()} should be called to get 372 the refreshed list of all available tracks in a data source.</p> 373 374 <p>To set the track to use with the {@link android.media.MediaPlayer}, you must 375 call {@link android.media.MediaPlayer#selectTrack selectTrack()}, using the index 376 position for the track you want to use.</p> 377 378 <p>To be notified when the text track is ready to play, implement the 379 {@link android.media.MediaPlayer.OnTimedTextListener} interface and pass 380 it to {@link android.media.MediaPlayer#setOnTimedTextListener setOnTimedTextListener()}.</p> 381 382 383 <h3 id="AudioEffects">Audio effects</h3> 384 385 <p>The {@link android.media.audiofx.AudioEffect} class now supports additional audio 386 pre-processing types when capturing audio:</p> 387 <ul> 388 <li>Acoustic Echo Canceler (AEC) with {@link android.media.audiofx.AcousticEchoCanceler} 389 removes the contribution of the signal received from the remote party from the captured audio signal.</li> 390 <li>Automatic Gain Control (AGC) with {@link android.media.audiofx.AutomaticGainControl} 391 automatically normalizes the output of the captured signal.</li> 392 <li>Noise Suppressor (NS) with {@link android.media.audiofx.NoiseSuppressor} 393 removes background noise from the captured signal.</li> 394 </ul> 395 396 <p>You can apply these pre-processor effects on audio captured with an {@link 397 android.media.AudioRecord} using one of the {@link android.media.audiofx.AudioEffect} 398 subclasses.</p> 399 400 <p class="note"><strong>Note:</strong> It's not guaranteed that all devices support these 401 effects, so you should always first check availability by calling {@link 402 android.media.audiofx.AcousticEchoCanceler#isAvailable isAvailable()} on the corresponding 403 audio effect class.</p> 404 405 406 <h3 id="Gapless">Gapless playback</h3> 407 408 <p>You can now perform gapless playback between two separate 409 {@link android.media.MediaPlayer} objects. At any time before your first {@link android.media.MediaPlayer} finishes, 410 call {@link android.media.MediaPlayer#setNextMediaPlayer setNextMediaPlayer()} and Android 411 attempts to start the second player the moment that the first one stops.</p> 412 413 414 Media router. The new APIs MediaRouter, MediaRouteActionProvider, and MediaRouteButton provide 415 standard mechanisms and UI for choosing where to play media. 416 417 418 <h2 id="Camera">Camera</h2> 419 420 <h3 id="AutoFocus">Auto focus movement</h3> 421 422 <p>The new interface {@link android.hardware.Camera.AutoFocusMoveCallback} allows you to listen 423 for changes to the auto focus movement. You can register your interface with {@link 424 android.hardware.Camera#setAutoFocusMoveCallback setAutoFocusMoveCallback()}. Then when the camera 425 is in a continuous autofocus mode ({@link 426 android.hardware.Camera.Parameters#FOCUS_MODE_CONTINUOUS_VIDEO} or 427 {@link android.hardware.Camera.Parameters#FOCUS_MODE_CONTINUOUS_PICTURE}), you'll receive a call 428 to {@link android.hardware.Camera.AutoFocusMoveCallback#onAutoFocusMoving onAutoFocusMoving()}, 429 which tells you whether auto focus has started moving or has stopped moving.</p> 430 431 <h3 id="CameraSounds">Camera sounds</h3> 432 433 <p>The {@link android.media.MediaActionSound} class provides a simple set of APIs to produce 434 standard sounds made by the camera or other media actions. You should use these APIs to play 435 the appropriate sound when building a custom still or video camera.</p> 436 437 <p>To play a sound, simply instantiate a {@link android.media.MediaActionSound} object, call 438 {@link android.media.MediaActionSound#load load()} to pre-load the desired sound, then at the 439 appropriate time, call {@link android.media.MediaActionSound#play play()}.</p> 440 441 442 443 <h2 id="Connectivity">Connectivity</h2> 444 445 446 <h3 id="AndroidBeam">Android Beam</h3> 447 448 <p>Android Beam™ now supports large payload transfers over Bluetooth. When you define the data 449 to transfer with either the new {@link android.nfc.NfcAdapter#setBeamPushUris setBeamPushUris()} 450 method or the new callback interface {@link android.nfc.NfcAdapter.CreateBeamUrisCallback}, Android 451 hands off the data transfer to Bluetooth or another alternate transport to 452 achieve faster transfer speeds. This is especially useful for large payloads such as image and 453 audio files and requires no visible pairing between the devices. No additional work is required by 454 your app to take advantage of transfers over Bluetooth.</p> 455 456 <p>The {@link android.nfc.NfcAdapter#setBeamPushUris setBeamPushUris()} method takes an array of 457 {@link android.net.Uri} objects that specify the data you want to transfer from your app. 458 Alternatively, you can implement the {@link android.nfc.NfcAdapter.CreateBeamUrisCallback} 459 interface, which you can specify for your activity by calling {@link 460 android.nfc.NfcAdapter#setBeamPushUrisCallback setBeamPushUrisCallback()}.</p> 461 462 <p>When using the 463 callback interface, the system calls the interface's {@link 464 android.nfc.NfcAdapter.CreateBeamUrisCallback#createBeamUris createBeamUris()} method when the 465 user executes a share with Android Beam so that you can define the URIs to share at share-time. 466 This is useful if the URIs to share might vary depending on the user context within the 467 activity, whereas calling {@link android.nfc.NfcAdapter#setBeamPushUris setBeamPushUris()} is 468 useful when the URIs to share are unchanging and you can safely define them ahead of time.</p> 469 470 471 472 473 474 <h3 id="LocalNsd">Network service discovery</h3> 475 476 <p>Android 4.1 adds support for multicast DNS-based service discovery, which allows you to 477 find and connect to services offered by peer devices over Wi-Fi, such as mobile devices, 478 printers, cameras, media players, and others that are registered on the local network.</p> 479 480 <p>The new package {@link android.net.nsd} contains the new APIs that allow you to 481 broadcast your services on the local network, discover local devices on the network, and 482 connect to devices.</p> 483 484 <p>To register your service, you must first create an {@link android.net.nsd.NsdServiceInfo} 485 object and define the various properties of your service with methods such as 486 {@link android.net.nsd.NsdServiceInfo#setServiceName setServiceName()}, 487 {@link android.net.nsd.NsdServiceInfo#setServiceType setServiceType()}, and 488 {@link android.net.nsd.NsdServiceInfo#setPort setPort()}. 489 </p> 490 491 <p>Then you need to implement {@link android.net.nsd.NsdManager.RegistrationListener} 492 and pass it to {@link android.net.nsd.NsdManager#registerService registerService()} 493 with your {@link android.net.nsd.NsdServiceInfo}.</p> 494 495 <p>To discover services on the network, implement {@link 496 android.net.nsd.NsdManager.DiscoveryListener} and pass it to {@link 497 android.net.nsd.NsdManager#discoverServices discoverServices()}.</p> 498 499 <p>When your {@link 500 android.net.nsd.NsdManager.DiscoveryListener} receives callbacks about services 501 found, you need to resolve the service by calling 502 {@link android.net.nsd.NsdManager#resolveService resolveService()}, passing it an 503 implementation of {@link android.net.nsd.NsdManager.ResolveListener} that receives 504 an {@link android.net.nsd.NsdServiceInfo} object that contains information about the 505 discovered service, allowing you to initiate the connection.</p> 506 507 508 509 <h3 id="WiFiNsd">Wi-Fi P2P service discovery</h3> 510 511 <p>The Wi-Fi P2P APIs are enhanced in Android 4.1 to support pre-association service discovery in 512 the {@link android.net.wifi.p2p.WifiP2pManager}. This allows you to discover and filter nearby 513 devices by services using Wi-Fi P2P before connecting to one, while Network Service 514 Discovery allows you to discover a service on an existing connected network (such as a local Wi-Fi 515 network).</p> 516 517 <p>To broadcast your app as a service over Wi-Fi so that other devices can discover 518 your app and connect to it, call {@link 519 android.net.wifi.p2p.WifiP2pManager#addLocalService addLocalService()} with a 520 {@link android.net.wifi.p2p.nsd.WifiP2pServiceInfo} object that describes your app services.</p> 521 522 <p>To initiate discover of nearby devices over Wi-Fi, you need to first decide whether you'll 523 communicate using Bonjour or Upnp. To use Bonjour, first set up some callback listeners with 524 {@link android.net.wifi.p2p.WifiP2pManager#setDnsSdResponseListeners setDnsSdResponseListeners()}, which takes both a {@link android.net.wifi.p2p.WifiP2pManager.DnsSdServiceResponseListener} and {@link android.net.wifi.p2p.WifiP2pManager.DnsSdTxtRecordListener}. To use Upnp, call 525 {@link android.net.wifi.p2p.WifiP2pManager#setUpnpServiceResponseListener setUpnpServiceResponseListener()}, which takes a {@link android.net.wifi.p2p.WifiP2pManager.UpnpServiceResponseListener}.</p> 526 527 <p>Before you can start discovering services on local devices, you also need to call {@link android.net.wifi.p2p.WifiP2pManager#addServiceRequest addServiceRequest()}. When the {@link android.net.wifi.p2p.WifiP2pManager.ActionListener} you pass to this method receives a 528 successful callback, you can then begin discovering services on local devices by calling {@link 529 android.net.wifi.p2p.WifiP2pManager#discoverServices discoverServices()}.</p> 530 531 <p>When local services are discovered, you'll receive a callback to either the {@link 532 android.net.wifi.p2p.WifiP2pManager.DnsSdServiceResponseListener} or {@link 533 android.net.wifi.p2p.WifiP2pManager.UpnpServiceResponseListener}, depending on whether you 534 registered to use Bonjour or Upnp. The callback received in either case contains a 535 {@link android.net.wifi.p2p.WifiP2pDevice} object representing the peer device.</p> 536 537 538 539 540 <h3 id="NetworkUsage">Network usage</h3> 541 542 <p>The new method {@link android.net.ConnectivityManager#isActiveNetworkMetered} allows you to 543 check whether the device is currently connected to a metered network. By checking this state 544 before performing intensive network transactions, you can help manage the data usage that may cost your users money and make 545 informed decisions about whether to perform the transactions now or later (such as when the 546 device becomes connected to Wi-Fi).</p> 547 548 549 550 551 552 <h2 id="A11y">Accessibility</h2> 553 554 <h3 id="A11yService">Accessibility service APIs</h3> 555 556 <p>The reach of accessibility service APIs has been significantly increased in Android 4.1. It now 557 allows you to build services that monitor and respond to more input events, such as complex gestures 558 using {@link android.accessibilityservice.AccessibilityService#onGesture onGesture()} and other 559 input events through additions to the {@link android.view.accessibility.AccessibilityEvent}, {@link 560 android.view.accessibility.AccessibilityNodeInfo} and {@link 561 android.view.accessibility.AccessibilityRecord} classes.</p> 562 563 <p>Accessibility services can also perform actions on behalf of the user, including clicking, 564 scrolling and stepping through text using {@link 565 android.view.accessibility.AccessibilityNodeInfo#performAction performAction} and {@link 566 android.view.accessibility.AccessibilityNodeInfo#setMovementGranularities 567 setMovementGranularities}. The {@link 568 android.accessibilityservice.AccessibilityService#performGlobalAction performGlobalAction()} method 569 also allows services to perform actions such as Back, Home, and open Recent 570 Apps and Notifications.</p> 571 572 573 <h3 id="A11yCustomNav">Customizable app navigation</h3> 574 575 <p>When building an Android app, you can now customize navigation schemes by finding focusable 576 elements and input widgets using {@link 577 android.view.accessibility.AccessibilityNodeInfo#findFocus findFocus()} and {@link 578 android.view.accessibility.AccessibilityNodeInfo#focusSearch focusSearch()}, and set focus 579 using {@link android.view.accessibility.AccessibilityNodeInfo#setAccessibilityFocused 580 setAccessibilityFocused()}.</p> 581 582 583 <h3 id="A11yStructure">More accessible widgets</h3> 584 585 <p>The new {@code android.view.accessibility.AccessibilityNodeProvider} class allows you to 586 surface complex custom views to accessibility services so they can present the information in a 587 more accessible way. The {@code android.view.accessibility.AccessibilityNodeProvider} allows a user 588 widget with advanced content, such as a calendar grid, to present a logical semantic structure for 589 accessibility services that is completely separate from the widgets layout structure. This semantic 590 structure allows accessibility services to present a more useful interaction model for users who are 591 visually impaired.</p> 592 593 594 595 <h2 id="CopyPaste">Copy and Paste</h2> 596 597 <h3 id="CopyIntent">Copy and paste with intents</h3> 598 599 <p>You can now associate a {@link android.content.ClipData} object with an {@link 600 android.content.Intent} using the {@link android.content.Intent#setClipData setClipData()} method. 601 This is especially useful when using an intent to transfer multiple {@code content:} URIs to another 602 application, such as when sharing multiple documents. The {@code content:} URIs supplied 603 this way will also respect the intent's flags to offer read or write access, allowing you to grant 604 access to multiple URIs in an the intent. When starting an {@link 605 android.content.Intent#ACTION_SEND} or {@link 606 android.content.Intent#ACTION_SEND_MULTIPLE} intent, the URIs supplied in the intent are now 607 automatically propagated to the {@link android.content.ClipData} so that the receiver can have 608 access granted to them.</p> 609 610 611 <h5>Support for HTML and string styles</h5> 612 613 <p>The {@link android.content.ClipData} class now supports styled text (either as HTML or 614 Android <a 615 href="{@docRoot}guide/topics/resources/string-resource.html#FormattingAndStyling">styled 616 strings</a>). You can add HTML styled text to the {@link android.content.ClipData} with {@link 617 android.content.ClipData#newHtmlText newHtmlText()}.</p> 618 619 620 621 <h2 id="Renderscript">Renderscript</h2> 622 623 <p>Renderscript computation functionality has been enhanced with the following features:</p> 624 <ul> 625 <li>Support for multiple kernels within one script.</li> 626 <li>Support for reading from allocation with filtered samplers from compute in a new script API 627 {@code rsSample}.</li> 628 <li>Support for different levels of FP precision in {@code #pragma}.</li> 629 <li>Support for querying additional information from RS objects from a compute script.</li> 630 <li>Numerous performance improvements.</li> 631 </ul> 632 633 <p>New pragmas are also available to define the floating point precision required by your 634 compute Renderscripts. This lets you enable NEON like operations such as fast vector math operations 635 on the CPU path that wouldnt otherwise be possible with full IEEE 754-2008 standard.</p> 636 637 <p class="note"><strong>Note:</strong> The experimental Renderscript graphics engine is now 638 deprecated.</p> 639 640 641 642 <h2 id="Animation">Animation</h2> 643 644 <h3 id="ActivityOptions">Activity launch animations</h3> 645 646 <p>You can now launch an {@link android.app.Activity} using zoom animations or 647 your own custom animations. To specify the animation you want, use the {@link 648 android.app.ActivityOptions} APIs to build a {@link android.os.Bundle} that you can 649 then pass to any of the 650 methods that start an activity, such as {@link 651 android.app.Activity#startActivity(Intent,Bundle) startActivity()}.</p> 652 653 <p>The {@link android.app.ActivityOptions} class includes a different method for each 654 type of animation you may want to show as your activity opens:</p> 655 <dl> 656 <dt>{@link android.app.ActivityOptions#makeScaleUpAnimation makeScaleUpAnimation()}</dt> 657 <dd>Creates an animation that scales up the activity window from a specified starting 658 position on the screen and a specified starting size. For example, the home screen in 659 Android 4.1 uses this when opening an app.</dd> 660 <dt>{@link android.app.ActivityOptions#makeThumbnailScaleUpAnimation 661 makeThumbnailScaleUpAnimation()}</dt> 662 <dd>Creates an animation that scales up the activity window starting from a specified 663 position and a provided thumbnail image. For example, the Recent Apps window in 664 Android 4.1 uses this when returning to an app.</dd> 665 <dt>{@link android.app.ActivityOptions#makeCustomAnimation 666 makeCustomAnimation()}</dt> 667 <dd>Creates an animation defined by your own resources: one that defines the animation for 668 the activity opening and another for the activity being stopped.</dd> 669 </dl> 670 671 672 673 <h3 id="TimeAnimator">Time animator</h3> 674 675 <p>The new {@link android.animation.TimeAnimator} provides a simple callback 676 mechanism with the {@link android.animation.TimeAnimator.TimeListener} that notifies 677 you upon every frame of the animation. There is no duration, interpolation, or object value-setting with this Animator. The listener's callback receives information for each frame including 678 total elapsed time and the elapsed time since the previous animation frame.</p> 679 680 681 682 683 <h2 id="UI">User Interface</h2> 684 685 686 <h3 id="Notifications">Notifications</h3> 687 688 <p>In Android 4.1, you can create notifications with larger content regions, big image previews, 689 multiple action buttons, and configurable priority.</p> 690 691 <h5>Notification styles</h5> 692 693 <p>The new method {@link android.app.Notification.Builder#setStyle setStyle()} allows you to specify 694 one of three new styles for your notification that each offer a larger content region. To 695 specify the style for your large content region, pass {@link 696 android.app.Notification.Builder#setStyle setStyle()} one of the following objects:</p> 697 <dl> 698 <dt>{@link android.app.Notification.BigPictureStyle}</dt> 699 <dd>For notifications that includes a large image attachment.</dd> 700 <dt>{@link android.app.Notification.BigTextStyle}</dt> 701 <dd>For notifications that includes a lot of text, such as a single email.</dd> 702 <dt>{@link android.app.Notification.InboxStyle}</dt> 703 <dd>For notifications that include a list of strings, such as snippets from multiple emails.</dd> 704 </dl> 705 706 <h5>Notification actions</h5> 707 708 <p>There's now support for up to two action buttons that appear at the bottom of the 709 notification message, whether your notification uses the normal or larger style.</p> 710 711 <p>To add an action button, call {@link android.app.Notification.Builder#addAction 712 addAction()}. This method takes three arguments: a drawable resource for an icon, 713 text for the button, and a {@link android.app.PendingIntent} that defines the action 714 to perfrom.</p> 715 716 717 <h5>Priorities</h5> 718 719 <p>You can now hint to the system how important your notification is to affect the 720 order of your notification in the list by setting 721 the priority with {@link android.app.Notification.Builder#setPriority setPriority()}. You 722 can pass this one of five different priority levels defined by {@code PRIORITY_*} constants 723 in the {@link android.app.Notification} class. The default is {@link 724 android.app.Notification#PRIORITY_DEFAULT}, and there's two levels higher and two levels lower.</p> 725 726 <p>High priority notifications are things that users generally want to respond to quickly, 727 such as a new instant message, text message, or impending event reminder. Low priority 728 notifications are things like expired calendar events or app promotions.</p> 729 730 <h3 id="SystemUI">Controls for system UI</h3> 731 732 <p>Android 4.0 (Ice Cream Sandwich) added new flags to control the visibility of the system UI 733 elements, such as to dim the appearance of the system bar or make it disappear completely on handsets. 734 Android 4.1 adds a few more flags that allow you to further control the appearance of system 735 UI elements and your activity layout in relation to them by calling {@link 736 android.view.View#setSystemUiVisibility setSystemUiVisibility()} 737 and passing the following flags:</p> 738 739 <dl> 740 <dt>{@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}</dt> 741 <dd>Hides non-critical system UI (such as the status bar). 742 If your activity uses the action bar in overlay mode (by 743 enabling <a href="{@docRoot}reference/android/R.attr.html#windowActionBarOverlay">{@code 744 android:windowActionBarOverlay}</a>), then this flag also hides the action bar and does 745 so with a coordinated animation when both hiding and showing the two.</dd> 746 747 <dt>{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN}</dt> 748 <dd>Sets your activity layout to use the same screen area that's available when you've 749 enabled {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN} even if the system UI elements 750 are still visible. Although parts of your layout will be overlayed by the 751 system UI, this is useful if your app often hides and shows the system UI with 752 {@link android.view.View#SYSTEM_UI_FLAG_FULLSCREEN}, because it avoids your layout from 753 adjusting to the new layout bounds each time the system UI hides or appears.</dd> 754 755 <dt>{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION}</dt> 756 <dd>Sets your activity layout to use the same screen area that's available when you've 757 enabled {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION} (added in Android 4.0) 758 even if the system UI elements are still visible. Although parts of your layout will be 759 overlayed by the 760 navigation bar, this is useful if your app often hides and shows the navigation bar 761 with {@link android.view.View#SYSTEM_UI_FLAG_HIDE_NAVIGATION}, because it avoids your layout from 762 adjusting to the new layout bounds each time the navigation bar hides or appears.</dd> 763 764 <dt>{@link android.view.View#SYSTEM_UI_FLAG_LAYOUT_STABLE}</dt> 765 <dd>You might want to add this flag if you're using {@link 766 android.view.View#SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN} and/or {@link 767 android.view.View#SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION} to ensure that when you call 768 {@link android.view.View#fitSystemWindows fitSystemWindows()} on a view that the 769 bounds defined remain consistent with regard to the available screen space. 770 That is, with this flag set, {@link android.view.View#fitSystemWindows 771 fitSystemWindows()} will behave as if the visibility of system UI elements is unchanged 772 even after you hide all system UI.</dd> 773 <dd></dd> 774 </dl> 775 776 <p>For more discussion about the other related system UI flags, read about 777 those added in <a href="{@docRoot}about/versions/android-4.0.html#SystemUI">Android 4.0</a>.</p> 778 779 780 <h3 id="RemoteViews">Remote views</h3> 781 782 <p>{@link android.widget.GridLayout} and {@link android.view.ViewStub} 783 are now remotable views so you can use them in layouts for your 784 app widgets and notification custom layouts.</p> 785 786 787 788 <h3 id="Fonts">Font families</h3> 789 790 <p>Android 4.1 adds several more variants of the Roboto font style for a total of 10 variants, 791 and they're all usable by apps. Your apps now have access to the full set of both light and 792 condensed variants.</p> 793 794 <p>The complete set of Roboto font variants available is:</p> 795 796 <ul> 797 <li>Regular</li> 798 <li>Italic</li> 799 <li>Bold</li> 800 <li>Bold-italic</li> 801 <li>Light</li> 802 <li>Light-italic</li> 803 <li>Condensed regular</li> 804 <li>Condensed italic</li> 805 <li>Condensed bold</li> 806 <li>Condensed bold-italic</li> 807 </ul> 808 809 <p>You can apply any one of these with the new {@link android.R.attr#fontFamily} 810 attribute in combination with the {@link android.R.attr#textStyle} attribute.</p> 811 812 <p>Supported values for {@link android.R.attr#fontFamily} are:</p> 813 <ul> 814 <li>{@code "sans-serif"} for regular Roboto</li> 815 <li>{@code "sans-serif-light"} for Roboto Light</li> 816 <li>{@code "sans-serif-condensed"} for Roboto Condensed</li> 817 </ul> 818 819 <p>You can then apply bold and/or italic with {@link android.R.attr#textStyle} values 820 {@code "bold"} and {@code "italic"}. You can apply both like so: {@code 821 android:textStyle="bold|italic"}.</p> 822 823 <p>You can also use {@link android.graphics.Typeface#create Typeface.create()}. 824 For example, {@code Typeface.create("sans-serif-light", Typeface.NORMAL)}.</p> 825 826 827 828 829 830 831 <h2 id="Input">Input Framework</h2> 832 833 834 <h3 id="InputDevice">Multiple input devices</h3> 835 836 <p>The new {@link android.hardware.input.InputManager} class allows you to query the 837 set of input devices current connected and register to be notified when a new device 838 is added, changed, or removed. This is particularly useful if you're building a game 839 that supports multiple players and you want to detect how many controllers are connected 840 and when there are changes to the number of controllers.</p> 841 842 <p>You can query all input devices connected by calling 843 {@link android.hardware.input.InputManager#getInputDeviceIds()}. This returns 844 an array of integers, each of which is an ID for a different input device. You can then call 845 {@link android.hardware.input.InputManager#getInputDevice getInputDevice()} to acquire 846 an {@link android.view.InputDevice} for a specified input device ID.</p> 847 848 <p>If you want to be informed when new input devices are connected, changed, or disconnected, 849 implement the {@link android.hardware.input.InputManager.InputDeviceListener} interface and 850 register it with {@link android.hardware.input.InputManager#registerInputDeviceListener 851 registerInputDeviceListener()}.</p> 852 853 <h3 id="Vibrate">Vibrate for input controllers</h3> 854 855 <p>If connected input devices have their own vibrate capabilities, you can now control 856 the vibration of those devices using the existing {@link android.os.Vibrator} APIs simply 857 by calling {@link android.view.InputDevice#getVibrator()} on the {@link android.view.InputDevice}.</p> 858 859 860 861 <h2 id="Permissions">Permissions</h2> 862 863 <p>The following are new permissions:</p> 864 865 <dl> 866 <dt>{@link android.Manifest.permission#READ_EXTERNAL_STORAGE}</dt> 867 <dd>Provides protected read access to external storage. In Android 4.1 by 868 default all applications still have read 869 access. This will be changed in a future release to require that applications explicitly request 870 read access using this permission. If your application already requests write access, it will 871 automatically get read access as well. There is a new developer option to turn on read access 872 restriction, for developers to test their applications against how Android will behave in the 873 future.</dd> 874 <dt>{@link android.Manifest.permission#READ_USER_DICTIONARY}</dt> 875 <dd>Allows an application to read the user dictionary. This should only be required by an 876 IME, or a dictionary editor like the Settings app.</dd> 877 <dt>{@link android.Manifest.permission#READ_CALL_LOG}</dt> 878 <dd>Allows an application to read the system's call log that contains information about 879 incoming and outgoing calls.</dd> 880 <dt>{@link android.Manifest.permission#WRITE_CALL_LOG}</dt> 881 <dd>Allows an application to modify the system's call log stored on your phone</dd> 882 <dt>{@link android.Manifest.permission#WRITE_USER_DICTIONARY}</dt> 883 <dd>Allows an application to write to the user's word dictionary.</dd> 884 </dl> 885 886 887 <h2 id="DeviceFeatures">Device Features</h2> 888 889 <p>Android 4.1 includes a new feature declaration for devices that are dedicated 890 to displaying the user interface on a television screen: {@link 891 android.content.pm.PackageManager#FEATURE_TELEVISION}. To declare that your app requires 892 a television interface, declare this feature in your manifest file with the <a href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code <uses-feature>}</a> element:</p> 893 <pre> 894 <manifest ... > 895 <uses-feature android:name="android.hardware.type.television" 896 android:required="true" /> 897 ... 898 </manifest> 899 </pre> 900 901 <p>This feature defines "television" to be a typical living room television experience: 902 displayed on a big screen, where the user is sitting far away and the dominant form of 903 input is be something like a d-pad, and generally not through touch or a 904 mouse/pointer-device.</p> 905 906 907 908 909 910 911 912 913
