activity-element.jd revision cd1b08e1e239269f7d0d48119505313f52d3dd5a
1page.title=<activity> 2parent.title=The AndroidManifest.xml File 3parent.link=manifest-intro.html 4@jd:body 5 6<dl class="xml"> 7<dt>syntax:</dt> 8<dd><pre class="stx"><activity android:<a href="#reparent">allowTaskReparenting</a>=["true" | "false"] 9 android:<a href="#always">alwaysRetainTaskState</a>=["true" | "false"] 10 android:<a href="#clear">clearTaskOnLaunch</a>=["true" | "false"] 11 android:<a href="#config">configChanges</a>=["mcc", "mnc", "locale", 12 "touchscreen", "keyboard", "keyboardHidden", 13 "navigation", "screenLayout", "fontScale", "uiMode", 14 "orientation", "screenSize", "smallestScreenSize"] 15 android:<a href="#enabled">enabled</a>=["true" | "false"] 16 android:<a href="#exclude">excludeFromRecents</a>=["true" | "false"] 17 android:<a href="#exported">exported</a>=["true" | "false"] 18 android:<a href="#finish">finishOnTaskLaunch</a>=["true" | "false"] 19 android:<a href="#hwaccel">hardwareAccelerated</a>=["true" | "false"] 20 android:<a href="#icon">icon</a>="<i>drawable resource</i>" 21 android:<a href="#label">label</a>="<i>string resource</i>" 22 android:<a href="#lmode">launchMode</a>=["multiple" | "singleTop" | 23 "singleTask" | "singleInstance"] 24 android:<a href="#multi">multiprocess</a>=["true" | "false"] 25 android:<a href="#nm">name</a>="<i>string</i>" 26 android:<a href="#nohist">noHistory</a>=["true" | "false"] <!-- ##api level 3## --> 27 android:<a href="#prmsn">permission</a>="<i>string</i>" 28 android:<a href="#proc">process</a>="<i>string</i>" 29 android:<a href="#screen">screenOrientation</a>=["unspecified" | "user" | "behind" | 30 "landscape" | "portrait" | 31 "reverseLandscape" | "reversePortrait" | 32 "sensorLandscape" | "sensorPortrait" | 33 "sensor" | "fullSensor" | "nosensor"] 34 android:<a href="#state">stateNotNeeded</a>=["true" | "false"] 35 android:<a href="#aff">taskAffinity</a>="<i>string</i>" 36 android:<a href="#theme">theme</a>="<i>resource or theme</i>" 37 android:<a href="#uioptions">uiOptions</a>=["none" | "splitActionBarWhenNarrow"] 38 android:<a href="#wsoft">windowSoftInputMode</a>=["stateUnspecified", 39 "stateUnchanged", "stateHidden", 40 "stateAlwaysHidden", "stateVisible", 41 "stateAlwaysVisible", "adjustUnspecified", 42 "adjustResize", "adjustPan"] > <!-- ##api level 3## --> 43 . . . 44</activity></pre></dd> 45 46<dt>contained in:</dt> 47<dd><code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code></dd> 48 49<dt>can contain:</dt> 50<dd><code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> 51<br/><code><a href="{@docRoot}guide/topics/manifest/meta-data-element.html"><meta-data></a></code></dd> 52 53<dt>description:</dt> 54<dd>Declares an activity (an {@link android.app.Activity} subclass) that 55implements part of the application's visual user interface. All activities 56must be represented by {@code <activity>} 57elements in the manifest file. Any that are not declared there will not be seen 58by the system and will never be run. 59 60<dt>attributes:</dt> 61<dd><dl class="attr"> 62<dt><a name="reparent"></a>{@code android:allowTaskReparenting}</dt> 63<dd>Whether or not the activity can move from the task that started it to 64the task it has an affinity for when that task is next brought to the 65front — "{@code true}" if it can move, and "{@code false}" if it 66must remain with the task where it started. 67 68<p> 69If this attribute is not set, the value set by the corresponding 70<code><a href="{@docRoot}guide/topics/manifest/application-element.html#reparent">allowTaskReparenting</a></code> 71attribute of the <code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element 72applies to the activity. The default value is "{@code false}". 73</p> 74 75<p> 76Normally when an activity is started, it's associated with the task of 77the activity that started it and it stays there for its entire lifetime. 78You can use this attribute to force it to be re-parented to the task it 79has an affinity for when its current task is no longer displayed. 80Typically, it's used to cause the activities of an application to move 81to the main task associated with that application. 82</p> 83 84<p> 85For example, if an e-mail message contains a link to a web page, clicking 86the link brings up an activity that can display the page. That activity 87is defined by the browser application, but is launched as part of the e-mail 88task. If it's reparented to the browser task, it will be shown when the 89browser next comes to the front, and will be absent when the e-mail task 90again comes forward. 91</p> 92 93<p> 94The affinity of an activity is defined by the 95<code><a href="#aff">taskAffinity</a></code> attribute. The affinity 96of a task is determined by reading the affinity of its root activity. 97Therefore, by definition, a root activity is always in a task with the 98same affinity. Since activities with "{@code singleTask}" or 99"{@code singleInstance}" launch modes can only be at the root of a task, 100re-parenting is limited to the "{@code standard}" and "{@code singleTop}" 101modes. (See also the <code><a href="#lmode">launchMode</a></code> 102attribute.) 103</p></dd> 104 105<dt><a name="always"></a>{@code android:alwaysRetainTaskState}</dt> 106<dd>Whether or not the state of the task that the activity is in will always 107be maintained by the system — "{@code true}" if it will be, and 108"{@code false}" if the system is allowed to reset the task to its initial 109state in certain situations. The default value is "{@code false}". This 110attribute is meaningful only for the root activity of a task; it's ignored 111for all other activities. 112 113<p> 114Normally, the system clears a task (removes all activities from the stack 115above the root activity) in certain situations when the user re-selects that 116task from the home screen. Typically, this is done if the user hasn't visited 117the task for a certain amount of time, such as 30 minutes. 118</p> 119 120<p> 121However, when this attribute is "{@code true}", users will always return 122to the task in its last state, regardless of how they get there. This is 123useful, for example, in an application like the web browser where there is 124a lot of state (such as multiple open tabs) that users would not like to lose. 125</p></dd> 126 127<dt><a name="clear"></a>{@code android:clearTaskOnLaunch}</dt> 128<dd>Whether or not all activities will be removed from the task, except for 129the root activity, whenever it is re-launched from the home screen — 130"{@code true}" if the task is always stripped down to its root activity, and 131"{@code false}" if not. The default value is "{@code false}". This attribute 132is meaningful only for activities that start a new task (the root activity); 133it's ignored for all other activities in the task. 134 135<p> 136When the value is "{@code true}", every time users start the task again, they 137are brought to its root activity, regardless of what they were last doing in 138the task and regardless of whether they used BACK or HOME to last leave it. 139When the value is "{@code false}", the task may be cleared of activities in 140some situations (see the 141<code><a href="#always">alwaysRetainTaskState</a></code> attribute), but not always. 142</p> 143 144<p> 145Suppose, for example, that someone launches activity P from the home screen, 146and from there goes to activity Q. The user next presses HOME, and then returns 147to activity P. Normally, the user would see activity Q, since that is what they 148were last doing in P's task. However, if P set this flag to "{@code true}", all 149of the activities on top of it (Q in this case) were removed when the user pressed 150HOME and the task went to the background. So the user sees only P when returning 151to the task. 152</p> 153 154<p> 155If this attribute and <code><a href="#reparent">allowTaskReparenting</a></code> 156are both "{@code true}", any activities that can be re-parented are moved to 157the task they share an affinity with; the remaining activities are then dropped, 158as described above. 159</p></dd> 160 161<dt><a name="config"></a>{@code android:configChanges}</dt> 162<dd>Lists configuration changes that the activity will handle itself. When a configuration 163change occurs at runtime, the activity is shut down and restarted by default, but declaring a 164configuration with this attribute will prevent the activity from being restarted. Instead, the 165activity remains running and its <code>{@link android.app.Activity#onConfigurationChanged 166onConfigurationChanged()}</code> method is called. 167 168<p class="note"><strong>Note:</strong> Using this attribute should be 169avoided and used only as a last-resort. Please read <a 170href="{@docRoot}guide/topics/resources/runtime-changes.html">Handling Runtime Changes</a> for more 171information about how to properly handle a restart due to a configuration change.</p> 172 173<p> 174Any or all of the following strings are valid values for this attribute. Multiple values are 175separated by '{@code |}' — for example, "{@code locale|navigation|orientation}". 176</p> 177 178<table> 179<tr> 180 <th>Value</th> 181 <th>Description</th> 182</tr><tr> 183 <td>"{@code mcc}"</td> 184 <td>The IMSI mobile country code (MCC) has changed — 185 a SIM has been detected and updated the MCC.</td> 186</tr><tr> 187 <td>"{@code mnc}"</td> 188 <td>The IMSI mobile network code (MNC) has changed — 189 a SIM has been detected and updated the MNC.</td> 190</tr><tr> 191 <td>"{@code locale}"</td> 192 <td>The locale has changed — the user has selected a new 193 language that text should be displayed in.</td> 194</tr><tr> 195 <td>"{@code touchscreen}"</td> 196 <td>The touchscreen has changed. (This should never normally happen.)</td> 197</tr><tr> 198 <td>"{@code keyboard}"</td> 199 <td>The keyboard type has changed — for example, the user has 200 plugged in an external keyboard.</td> 201</tr><tr> 202 <td>"{@code keyboardHidden}"</td> 203 <td>The keyboard accessibility has changed — for example, the 204 user has revealed the hardware keyboard.</td> 205</tr><tr> 206 <td>"{@code navigation}"</td> 207 <td>The navigation type (trackball/dpad) has changed. (This should never normally happen.)</td> 208</tr><tr> 209 <td>"{@code screenLayout}"</td> 210 <td>The screen layout has changed — this might be caused by a 211 different display being activated.</td> 212 </tr><tr> 213 <td>"{@code fontScale}"</td> 214 <td>The font scaling factor has changed — the user has selected 215 a new global font size.</td> 216 </tr><tr> 217 <td>"{@code uiMode}"</td> 218 <td>The user interface mode has changed — this can be caused when the user places the 219device into a desk/car dock or when the the night mode changes. See {@link 220android.app.UiModeManager}. <em>Introduced in API Level 8</em>.</td> 221 </tr><tr> 222 <td>"{@code orientation}"</td> 223 <td>The screen orientation has changed — the user has rotated the device. 224 <p class="note"><strong>Note:</strong> If your application targets API level 13 or higher (as 225declared by the <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#min">{@code 226minSdkVersion}</a> and <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html#target">{@code 227targetSdkVersion}</a> attributes), then you should also declare the {@code "screenSize"} 228configuration, because it also changes when a device switches between portrait and landscape 229orientations.</p></td> 230 </tr><tr> 231 <td>"{@code screenSize}"</td> 232 <td>The current available screen size has changed. This represents a change in the currently 233available size, relative to the current aspect ratio, so will change when the user switches between 234landscape and portrait. However, if your application targets API level 12 or lower, then your 235activity always handles this configuration change itself (this configuration change does not restart 236your activity, even when running on an Android 3.2 or higher device). 237 <p><em>Added in API level 13.</em></p></td> 238 </tr><tr> 239 <td>"{@code smallestScreenSize}"</td> 240 <td>The physical screen size has changed. This represents a change in size regardless of 241orientation, so will only change when the actual physical screen size has changed such as switching 242to an external display. A change to this configuration corresponds to a change in the <a 243href="{@docRoot}guide/topics/resources/providing-resources.html#SmallestScreenWidthQualifier"> 244smallestWidth configuration</a>. However, if your application targets API level 12 or lower, then 245your activity always handles this configuration change itself (this configuration change does not 246restart your activity, even when running on an Android 3.2 or higher device). 247 <p><em>Added in API level 13.</em></p></td> 248 </tr> 249</table> 250 251<p> 252All of these configuration changes can impact the resource values seen by the 253application. Therefore, when <code>{@link android.app.Activity#onConfigurationChanged 254onConfigurationChanged()}</code> is called, it will generally be necessary to again 255retrieve all resources (including view layouts, drawables, and so on) to correctly 256handle the change. 257</p></dd> 258 259<dt><a name="enabled"></a>{@code android:enabled}</dt> 260<dd>Whether or not the activity can be instantiated by the system — 261"{@code true}" if it can be, and "{@code false}" if not. The default value 262is "{@code true}". 263 264<p> 265The <code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element has its own 266<code><a href="{@docRoot}guide/topics/manifest/application-element.html#enabled">enabled</a></code> 267attribute that applies to all application components, including activities. The 268<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 269and {@code <activity>} attributes must both be "{@code true}" (as they both 270are by default) for the system to be able to instantiate the activity. If either 271is "{@code false}", it cannot be instantiated. 272</p></dd> 273 274<dt><a name="exclude"></a>{@code android:excludeFromRecents}</dt> 275<dd>Whether or not the activity should be excluded from the list of recently 276launched activities that can be displayed to users — "{@code true}" if 277it should be excluded, and "{@code false}" if it should be included. 278The default value is "{@code false}". 279</p></dd> 280 281<dt><a name="exported"></a>{@code android:exported}</dt> 282<dd>Whether or not the activity can be launched by components of other 283applications — "{@code true}" if it can be, and "{@code false}" if not. 284If "{@code false}", the activity can be launched only by components of the 285same application or applications with the same user ID. 286 287<p> 288The default value depends on whether the activity contains intent filters. The 289absence of any filters means that the activity can be invoked only by specifying 290its exact class name. This implies that the activity is intended only for 291application-internal use (since others would not know the class name). So in 292this case, the default value is "{@code false}". 293On the other hand, the presence of at least one filter implies that the activity 294is intended for external use, so the default value is "{@code true}". 295</p> 296 297<p> 298This attribute is not the only way to limit an activity's exposure to other 299applications. You can also use a permission to limit the external entities that 300can invoke the activity (see the 301<code><a href="{@docRoot}guide/topics/manifest/activity-element.html#prmsn">permission</a></code> 302attribute). 303</p></dd> 304 305<dt><a name="finish"></a>{@code android:finishOnTaskLaunch}</dt> 306<dd>Whether or not an existing instance of the activity should be shut down 307(finished) whenever the user again launches its task (chooses the task on the 308home screen) — "{@code true}" if it should be shut down, and "{@code false}" 309if not. The default value is "{@code false}". 310 311<p> 312If this attribute and 313<code><a href="{@docRoot}guide/topics/manifest/activity-element.html#reparent">allowTaskReparenting</a></code> 314are both "{@code true}", this attribute trumps the other. The affinity of the 315activity is ignored. The activity is not re-parented, but destroyed. 316</p> 317 318<dt><a name="hwaccel"></a>{@code android:hardwareAccelerated}</dt> 319<dd>Whether or not hardware-accelerated rendering should be enabled for this 320Activity — "{@code true}" if it should be enabled, and "{@code false}" if 321not. The default value is "{@code false}". 322 323<p>Starting from Android 3.0, a hardware-accelerated OpenGL renderer is 324available to applications, to improve performance for many common 2D graphics 325operations. When the hardware-accelerated renderer is enabled, most operations 326in Canvas, Paint, Xfermode, ColorFilter, Shader, and Camera are accelerated. 327This results in smoother animations, smoother scrolling, and improved 328responsiveness overall, even for applications that do not explicitly make use 329the framework's OpenGL libraries. </p> 330 331<p>Note that not all of the OpenGL 2D operations are accelerated. If you enable 332the hardware-accelerated renderer, test your application to ensure that it can 333make use of the renderer without errors.</p> 334</dd> 335 336<dt><a name="icon"></a>{@code android:icon}</dt> 337<dd>An icon representing the activity. The icon is displayed to users when 338a representation of the activity is required on-screen. For example, icons 339for activities that initiate tasks are displayed in the launcher window. 340The icon is often accompanied by a label (see the <a href="#label">{@code 341android:label}</a> attribute). 342</p> 343 344<p> 345This attribute must be set as a reference to a drawable resource containing 346the image definition. If it is not set, the icon specified for the application 347as a whole is used instead (see the 348<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 349element's <code><a href="{@docRoot}guide/topics/manifest/application-element.html#icon">icon</a></code> attribute). 350</p> 351 352<p> 353The activity's icon — whether set here or by the 354<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 355element — is also the default icon for all the activity's intent filters (see the 356<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> element's 357<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html#icon">icon</a></code> attribute). 358</p></dd> 359 360<dt><a name="label"></a>{@code android:label}</dt> 361<dd>A user-readable label for the activity. The label is displayed on-screen 362when the activity must be represented to the user. It's often displayed along 363with the activity icon. 364 365<p> 366If this attribute is not set, the label set for the application as a whole is 367used instead (see the <code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element's 368<code><a href="{@docRoot}guide/topics/manifest/application-element.html#label">label</a></code> attribute). 369</p> 370 371<p> 372The activity's label — whether set here or by the 373<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element — is also the 374default label for all the activity's intent filters (see the 375<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html"><intent-filter></a></code> element's 376<code><a href="{@docRoot}guide/topics/manifest/intent-filter-element.html#label">label</a></code> attribute). 377</p> 378 379<p> 380The label should be set as a reference to a string resource, so that 381it can be localized like other strings in the user interface. 382However, as a convenience while you're developing the application, 383it can also be set as a raw string. 384</p></dd> 385 386<dt><a name="lmode"></a>{@code android:launchMode}</dt> 387<dd>An instruction on how the activity should be launched. There are four modes 388that work in conjunction with activity flags ({@code FLAG_ACTIVITY_*} constants) 389in {@link android.content.Intent} objects to determine what should happen when 390the activity is called upon to handle an intent. They are:</p> 391 392<p style="margin-left: 2em">"{@code standard}" 393<br>"{@code singleTop}" 394<br>"{@code singleTask}" 395<br>"{@code singleInstance}"</p> 396 397<p> 398The default mode is "{@code standard}". 399</p> 400 401<p> 402As shown in the table below, the modes fall into two main groups, with 403"{@code standard}" and "{@code singleTop}" activities on one side, and 404"{@code singleTask}" and "{@code singleInstance}" activities on the other. 405An activity with the "{@code standard}" or "{@code singleTop}" launch mode 406can be instantiated multiple times. The instances can belong to any task 407and can be located anywhere in the activity stack. Typically, they're 408launched into the task that called 409<code>{@link android.content.Context#startActivity startActivity()}</code> 410(unless the Intent object contains a 411<code>{@link android.content.Intent#FLAG_ACTIVITY_NEW_TASK}</code> 412instruction, in which case a different task is chosen — see the 413<a href="#aff">taskAffinity</a> attribute). 414</p> 415 416<p> 417In contrast, "<code>singleTask</code>" and "<code>singleInstance</code>" activities 418can only begin a task. They are always at the root of the activity stack. 419Moreover, the device can hold only one instance of the activity at a time 420— only one such task. 421</p> 422 423<p> 424The "{@code standard}" and "{@code singleTop}" modes differ from each other 425in just one respect: Every time there's a new intent for a "{@code standard}" 426activity, a new instance of the class is created to respond to that intent. 427Each instance handles a single intent. 428Similarly, a new instance of a "{@code singleTop}" activity may also be 429created to handle a new intent. However, if the target task already has an 430existing instance of the activity at the top of its stack, that instance 431will receive the new intent (in an 432<code>{@link android.app.Activity#onNewIntent onNewIntent()}</code> call); 433a new instance is not created. 434In other circumstances — for example, if an existing instance of the 435"{@code singleTop}" activity is in the target task, but not at the top of 436the stack, or if it's at the top of a stack, but not in the target task 437— a new instance would be created and pushed on the stack. 438</p> 439 440<p> 441The "{@code singleTask}" and "{@code singleInstance}" modes also differ from 442each other in only one respect: A "{@code singleTask}" activity allows other 443activities to be part of its task. It's always at the root of its task, but 444other activities (necessarily "{@code standard}" and "{@code singleTop}" 445activities) can be launched into that task. A "{@code singleInstance}" 446activity, on the other hand, permits no other activities to be part of its task. 447It's the only activity in the task. If it starts another activity, that 448activity is assigned to a different task — as if {@code 449FLAG_ACTIVITY_NEW_TASK} was in the intent. 450</p> 451 452<table> 453<tr> 454<th>Use Cases</th> 455<th>Launch Mode</th> 456<th>Multiple Instances?</th> 457<th>Comments</th> 458</tr> 459<tr> 460<td rowspan="2" style="width:20%;">Normal launches for most activities</td> 461<td>"<code>standard</code>"</td> 462<td>Yes</td> 463<td>Default. The system always creates a new instance of the activity in the 464target task and routes the intent to it.</td> 465</tr> 466<tr> 467<td>"<code>singleTop</code>"</td> 468<td>Conditionally</td> 469<td>If an instance of the activity already exists at the top of the target task, 470the system routes the intent to that instance through a call to its {@link 471android.app.Activity#onNewIntent onNewIntent()} method, rather than creating a 472new instance of the activity.</td> 473</tr> 474<tr> 475<td rowspan="2">Specialized launches<br> 476<em>(not recommended for general use)</em></td> 477<td>"<code>singleTask</code>"</td> 478<td>No</td> 479<td>The system creates the activity at the root of a new task and routes the 480intent to it. However, if an instance of the activity already exists, the system 481routes the intent to existing instance through a call to its {@link 482android.app.Activity#onNewIntent onNewIntent()} method, rather than creating a 483new one.</td> 484</tr> 485<tr> 486<td>"<code>singleInstance</code>"</td> 487<td>No</td> 488<td>Same as "<code>singleTask"</code>, except that the system doesn't launch any 489other activities into the task holding the instance. The activity is always the 490single and only member of its task.</td> 491</tr> 492</table> 493 494<p>As shown in the table above, <code>standard</code> is the default mode and is 495appropriate for most types of activities. <code>SingleTop</code> is also a 496common and useful launch mode for many types of activities. The other modes 497— <code>singleTask</code> and <code>singleInstance</code> — are 498<span style="color:red">not appropriate for most applications</span>, 499since they result in an interaction model that is likely to be unfamiliar to 500users and is very different from most other applications. 501 502<p>Regardless of the launch mode that you choose, make sure to test the usability 503of the activity during launch and when navigating back to it from 504other activities and tasks using the BACK key. </p> 505 506<p>For more information on launch modes and their interaction with Intent 507flags, see the 508<a href="{@docRoot}guide/topics/fundamentals/tasks-and-back-stack.html">Tasks and Back Stack</a> 509document. 510</p> 511</dd> 512 513<dt><a name="multi"></a>{@code android:multiprocess}</dt> 514<dd>Whether an instance of the activity can be launched into the process of the component 515that started it — "{@code true}" if it can be, and "{@code false}" if not. 516The default value is "{@code false}". 517 518<p> 519Normally, a new instance of an activity is launched into the process of the 520application that defined it, so all instances of the activity run in the same 521process. However, if this flag is set to "{@code true}", instances of the 522activity can run in multiple processes, allowing the system to create instances 523wherever they are used (provided permissions allow it), something that is almost 524never necessary or desirable. 525</p></dd> 526 527<dt><a name="nm"></a>{@code android:name}</dt> 528<dd>The name of the class that implements the activity, a subclass of 529{@link android.app.Activity}. The attribute value should be a fully qualified 530class name (such as, "{@code com.example.project.ExtracurricularActivity}"). 531However, as a shorthand, if the first character of the name is a period 532(for example, "{@code .ExtracurricularActivity}"), it is appended to the 533package name specified in the 534<code><a href="{@docRoot}guide/topics/manifest/manifest-element.html"><manifest></a></code> 535element. 536<p>Once you publish your application, you <a 537href="http://android-developers.blogspot.com/2011/06/things-that-cannot-change.html">should not 538change this name</a> (unless you've set <code><a 539href="#exported">android:exported</a>="false"</code>).</p> 540 541<p> 542There is no default. The name must be specified. 543</p></dd> 544 545<!-- ##api level 3## --> 546<dt><a name="nohist"></a>{@code android:noHistory}</dt> 547<dd>Whether or not the activity should be removed from the activity stack and 548finished (its <code>{@link android.app.Activity#finish finish()}</code> 549method called) when the user navigates away from it and it's no longer 550visible on screen — "{@code true}" if it should be finished, and 551"{@code false}" if not. The default value is "{@code false}". 552 553<p> 554A value of "{@code true}" means that the activity will not leave a 555historical trace. It will not remain in the activity stack for the task, 556so the user will not be able to return to it. 557</p> 558 559<p> 560This attribute was introduced in API Level 3. 561</p> 562 563<dt><a name="prmsn"></a>{@code android:permission}</dt> 564<dd>The name of a permission that clients must have to launch the activity 565or otherwise get it to respond to an intent. If a caller of 566<code>{@link android.content.Context#startActivity startActivity()}</code> or 567<code>{@link android.app.Activity#startActivityForResult startActivityForResult()}</code> 568has not been granted the specified permission, its intent will not be 569delivered to the activity. 570 571<p> 572If this attribute is not set, the permission set by the 573<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 574element's 575<code><a href="{@docRoot}guide/topics/manifest/application-element.html#prmsn">permission</a></code> 576attribute applies to the activity. If neither attribute is set, the activity is 577not protected by a permission. 578</p> 579 580<p> 581For more information on permissions, see the 582<a href="{@docRoot}guide/topics/manifest/manifest-intro.html#sectperm">Permissions</a> 583section in the introduction and another document, 584<a href="{@docRoot}guide/topics/security/security.html">Security and 585Permissions</a>. 586</p></dd> 587 588<dt><a name="proc"></a>{@code android:process}</dt> 589<dd>The name of the process in which the activity should run. Normally, 590all components of an application run in the default process created for the 591application. It has the same name as the application package. The <code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> element's 592<code><a href="{@docRoot}guide/topics/manifest/application-element.html#proc">process</a></code> 593attribute can set a different default for all components. But each component 594can override the default, allowing you to spread your application across 595multiple processes. 596 597<p> 598If the name assigned to this attribute begins with a colon (':'), a new 599process, private to the application, is created when it's needed and 600the activity runs in that process. 601If the process name begins with a lowercase character, the activity will run 602in a global process of that name, provided that it has permission to do so. 603This allows components in different applications to share a process, reducing 604resource usage. 605</p></dd> 606 607<dt><a name="screen"></a>{@code android:screenOrientation}</dt> 608<dd>The orientation of the activity's display on the device. 609 610<p>The value can be any one of the following strings:</p> 611 612<table> 613<tr> 614 <td>"{@code unspecified}"</td> 615 <td>The default value. The system chooses the orientation. The policy it 616 uses, and therefore the choices made in specific contexts, may differ 617 from device to device.</td> 618</tr><tr> 619 <td>"{@code user}"</td> 620 <td>The user's current preferred orientation.</td> 621</tr><tr> 622 <td>"{@code behind}"</td> 623 <td>The same orientation as the activity that's immediately beneath it in 624 the activity stack.</td> 625</tr><tr> 626 <td>"{@code landscape}"</td> 627 <td>Landscape orientation (the display is wider than it is tall).</td> 628</tr><tr> 629 <td>"{@code portrait}"</td> 630 <td>Portrait orientation (the display is taller than it is wide).</td> 631</tr><tr> 632 <td>"{@code reverseLandscape}"</td> 633 <td>Landscape orientation in the opposite direction from normal landscape. 634<em>Added in API level 9.</em></td> 635</tr><tr> 636 <td>"{@code reversePortrait}"</td> 637 <td>Portrait orientation in the opposite direction from normal portrait. 638<em>Added in API level 9.</em></td> 639</tr><tr> 640 <td>"{@code sensorLandscape}"</td> 641 <td>Landscape orientation, but can be either normal or reverse landscape based on the device 642sensor. 643<em>Added in API level 9.</em></td> 644</tr><tr> 645 <td>"{@code sensorPortrait}"</td> 646 <td>Portrait orientation, but can be either normal or reverse portrait based on the device 647sensor. 648<em>Added in API level 9.</em></td> 649</tr><tr> 650 <td>"{@code sensor}"</td> 651 <td>The orientation is determined by the device orientation sensor. The orientation of the 652display depends on how the user is holding the device; it changes when the user rotates the 653device. Some devices, though, will not rotate to all four possible orientations, by default. To 654allow all four orientations, use {@code "fullSensor"}.</td> 655</tr><tr> 656 <td>"{@code fullSensor}"</td> 657 <td>The orientation is determined by the device orientation sensor for any of the 4 orientations. 658This is similar to {@code "sensor"} except this allows any of the 4 possible screen orientations, 659regardless of what the device will normally do (for example, some devices won't normally use reverse 660portrait or reverse landscape, but this enables those). <em>Added in API level 9.</em></td> 661</tr><tr> 662 <td>"{@code nosensor}"</td> 663 <td>The orientation is determined without reference to a physical orientation sensor. The sensor 664is ignored, so the display will not rotate based on how the user moves the device. Except for this 665distinction, the system chooses the orientation using the same policy as for the "{@code 666unspecified}" setting.</td> 667</tr> 668</table> 669 670<p class="note"><strong>Note:</strong> When you declare one of the landscape or portrait values, 671it is considered a hard requirement for the orientation in which the activity runs. As such, 672the value you declare enables filtering by services such as Android Market so your application is 673available only to devices that support the orientation required by your activities. For 674example, if you declare either {@code "landscape"}, {@code "reverseLandscape"}, or 675{@code "sensorLandscape"}, then your application will be available only to devices that support 676landscape orientation. However, you should also explicitly declare that 677your application requires either portrait or landscape orientation with the <a 678href="{@docRoot}guide/topics/manifest/uses-feature-element.html">{@code <uses-feature>}</a> 679element. For example, <code><uses-feature 680android:name="android.hardware.screen.portrait"/></code>. This is purely a filtering behavior 681provided by Android Market (and other services that support it) and the platform itself does not 682control whether your app can be installed when a device supports only certain orientations.</p> 683 684</dd> 685 686<dt><a name="state"></a>{@code android:stateNotNeeded}</dt> 687<dd>Whether or not the activity can be killed and successfully restarted 688without having saved its state — "{@code true}" if it can be restarted 689without reference to its previous state, and "{@code false}" if its previous 690state is required. The default value is "{@code false}". 691 692<p> 693Normally, before an activity is temporarily shut down to save resources, its 694<code>{@link android.app.Activity#onSaveInstanceState onSaveInstanceState()}</code> 695method is called. This method stores the current state of the activity in a 696{@link android.os.Bundle} object, which is then passed to 697<code>{@link android.app.Activity#onCreate onCreate()}</code> when the activity 698is restarted. If this attribute is set to "{@code true}", 699{@code onSaveInstanceState()} may not be called and {@code onCreate()} will 700be passed {@code null} instead of the Bundle — just as it was when the 701activity started for the first time. 702</p> 703 704<p> 705A "{@code true}" setting ensures that the activity can be restarted in the 706absence of retained state. For example, the activity that displays the 707home screen uses this setting to make sure that it does not get removed if it 708crashes for some reason. 709</p></dd> 710 711<dt><a name="aff"></a>{@code android:taskAffinity}</dt> 712<dd>The task that the activity has an affinity for. Activities with 713the same affinity conceptually belong to the same task (to the same 714"application" from the user's perspective). The affinity of a task 715is determined by the affinity of its root activity. 716 717<p> 718The affinity determines two things — the task that the activity is re-parented 719to (see the <code><a href="{@docRoot}guide/topics/manifest/activity-element.html#reparent">allowTaskReparenting</a></code> 720attribute) and the task that will house the activity when it is launched 721with the <code>{@link android.content.Intent#FLAG_ACTIVITY_NEW_TASK}</code> 722flag. 723</p> 724 725<p> 726By default, all activities in an application have the same affinity. You 727can set this attribute to group them differently, and even place 728activities defined in different applications within the same task. To 729specify that the activity does not have an affinity for any task, set 730it to an empty string. 731 732<p> 733If this attribute is not set, the activity inherits the affinity set 734for the application (see the 735<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 736element's 737<code><a href="{@docRoot}guide/topics/manifest/application-element.html#aff">taskAffinity</a></code> 738attribute). The name of the default affinity for an application is 739the package name set by the 740<code><a href="{@docRoot}guide/topics/manifest/manifest-element.html"><manifest></a></code> 741element. 742</p> 743 744<dt><a name="theme"></a>{@code android:theme}</dt> 745<dd>A reference to a style resource defining an overall theme for the activity. 746This automatically sets the activity's context to use this theme (see 747<code>{@link android.content.Context#setTheme setTheme()}</code>, and may also 748cause "starting" animations prior to the activity being launched (to better 749match what the activity actually looks like). 750 751<p> 752If this attribute is not set, the activity inherits the theme set for the 753application as a whole — from the 754<code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 755element's 756<code><a href="{@docRoot}guide/topics/manifest/application-element.html#theme">theme</a></code> 757attribute. If that attribute is also not set, the default system theme is used. For more 758information, see the <a 759href="{@docRoot}guide/topics/ui/themes.html">Styles and Themes</a> developer guide. 760</p> 761<dd> 762 763<!-- ##api level 14## --> 764<dt><a name="uioptions"></a>{@code android:uiOptions}</dt> 765<dd>Extra options for an activity's UI. 766 <p>Must be one of the following values.</p> 767 768 <table> 769 <tr><th>Value</th><th>Description</th></tr> 770 <tr><td>{@code "none"}</td><td>No extra UI options. This is the default.</td></tr> 771 <tr><td>{@code "splitActionBarWhenNarrow"}</td><td>Add a bar at 772the bottom of the screen to display action items in the {@link android.app.ActionBar}, when 773constrained for horizontal space (such as when in portrait mode on a handset). Instead of a small 774number of action items appearing in the action bar at the top of the screen, the action bar is 775split into the top navigation section and the bottom bar for action items. This ensures a reasonable 776amount of space is made available not only for the action items, but also for navigation and title 777elements at the top. Menu items are not split across the two bars; they always appear 778together.</td></tr> 779 </table> 780 <p>For more information about the action bar, see the <a 781href="{@docRoot}guide/topics/ui/actionbar.html">Action Bar</a> developer guide.</p> 782 <p>This attribute was added in API level 14.</p> 783</dd> 784 785 786<!-- ##api level 3## --> 787<dt><a name="wsoft"></a>{@code android:windowSoftInputMode}</dt> 788<dd>How the main window of the activity interacts with the window containing 789the on-screen soft keyboard. The setting for this attribute affects two 790things: 791 792<ul> 793<li>The state of the soft keyboard — whether it is hidden or visible 794— when the activity becomes the focus of user attention.</li> 795 796<li>The adjustment made to the activity's main window — whether it is 797resized smaller to make room for the soft keyboard or whether its contents 798pan to make the current focus visible when part of the window is covered by 799the soft keyboard.</li> 800</ul> 801 802<p> 803The setting must be one of the values listed in the following table, or a 804combination of one "{@code state...}" value plus one "{@code adjust...}" 805value. Setting multiple values in either group — multiple 806"{@code state...}" values, for example — has undefined results. 807Individual values are separated by a vertical bar ({@code |}). For example: 808</p> 809 810<pre><activity android:windowSoftInputMode="stateVisible|adjustResize" . . . ></pre> 811 812<p> 813Values set here (other than "{@code stateUnspecified}" and 814"{@code adjustUnspecified}") override values set in the theme. 815</p> 816 817<table> 818<tr> 819 <th>Value</th> 820 <th>Description</th> 821</tr><tr> 822 <td>"{@code stateUnspecified}"</td> 823 <td>The state of the soft keyboard (whether it is hidden or visible) 824 is not specified. The system will choose an appropriate state or 825 rely on the setting in the theme. 826 827 <p> 828 This is the default setting for the behavior of the soft keyboard. 829 </p></td> 830</tr></tr> 831 <td>"{@code stateUnchanged}"</td> 832 <td>The soft keyboard is kept in whatever state it was last in, 833 whether visible or hidden, when the activity comes to the fore.</td> 834</tr></tr> 835 <td>"{@code stateHidden}"</td> 836 <td>The soft keyboard is hidden when the user chooses the activity 837 — that is, when the user affirmatively navigates forward to the 838 activity, rather than backs into it because of leaving another activity.</td> 839</tr></tr> 840 <td>"{@code stateAlwaysHidden}"</td> 841 <td>The soft keyboard is always hidden when the activity's main window 842 has input focus.</td> 843</tr></tr> 844 <td>"{@code stateVisible}"</td> 845 <td>The soft keyboard is visible when that's normally appropriate 846 (when the user is navigating forward to the activity's main window).</td> 847</tr></tr> 848 <td>"{@code stateAlwaysVisible}"</td> 849 <td>The soft keyboard is made visible when the user chooses the 850 activity — that is, when the user affirmatively navigates forward 851 to the activity, rather than backs into it because of leaving another 852 activity.</td> 853</tr></tr> 854 <td>"{@code adjustUnspecified}"</td> 855 <td>It is unspecified whether the activity's main window resizes 856 to make room for the soft keyboard, or whether the contents 857 of the window pan to make the currentfocus visible on-screen. 858 The system will automatically select one of these modes depending 859 on whether the content of the window has any layout views that 860 can scroll their contents. If there is such a view, the window 861 will be resized, on the assumption that scrolling can make all 862 of the window's contents visible within a smaller area. 863 864 <p> 865 This is the default setting for the behavior of the main window. 866 </p></td> 867</tr></tr> 868 <td>"{@code adjustResize}"</td> 869 <td>The activity's main window is always resized to make room for 870 the soft keyboard on screen.</td> 871</tr></tr> 872 <td>"{@code adjustPan}"</td> 873 <td>The activity's main window is not resized to make room for the soft 874 keyboard. Rather, the contents of the window are automatically 875 panned so that the current focus is never obscured by the keyboard 876 and users can always see what they are typing. This is generally less 877 desirable than resizing, because the user may need to close the soft 878 keyboard to get at and interact with obscured parts of the window.</td> 879</tr> 880</table> 881 882<p> 883This attribute was introduced in API Level 3. 884</p></dd> 885</dl></dd> 886 887<!-- ##api level indication## --> 888<dt>introduced in:</dt> 889<dd>API Level 1 for all attributes except for 890<code><a href="#nohist">noHistory</a></code> and 891<code><a href="#wsoft">windowSoftInputMode</a></code>, which were added in API 892Level 3.</dd> 893 894<dt>see also:</dt> 895<dd><code><a href="{@docRoot}guide/topics/manifest/application-element.html"><application></a></code> 896<br/><code><a href="{@docRoot}guide/topics/manifest/activity-alias-element.html"><activity-alias></a></code></dd> 897</dl> 898