Android APIs
Added in API level 1
package

android.app

Contains high-level classes encapsulating the overall Android application model.

An Android application is defined using one or more of Android's four core application components. Two such application components are defined in this package: Activity and Service. The other two components are from the android.content package: BroadcastReceiver and ContentProvider.

An Activity is an application component that provides a screen with which users can interact in order to do something, such as dial the phone, take a photo, send an email, or view a map. An activity can start other activities, including activities that live in separate applications.

A Service is an application component that can perform long-running operations in the background without a user interface. For example, a service can handle network transactions, play music, or work with a content provider without the user being aware of the work going on.

The Fragment class is also an important part of an application's design—especially when designing for large screen devices, such as tablets. A fragment defines a distinct part of an activity's behavior, including the associated UI. It has its own lifecycle that is similar to that of the activity and can exist alongside other fragments that are embedded in the activity. While an activity is running, you can add and remove fragments and include each fragment in a back stack that's managed by the activity—allowing the user to navigate backwards through the fragment states, without leaving the activity.

This package also defines application utilities, such as dialogs, notifications, and the action bar.

For information about using some the classes in this package, see the following documents: Activities, Services, Fragments, Using the Action Bar, Creating Dialogs, and Notifying the User.

Interfaces

ActionBar.OnMenuVisibilityListener Listener for receiving events when action bar menus are shown or hidden. 
ActionBar.OnNavigationListener This interface was deprecated in API level 21. Action bar navigation modes are deprecated and not supported by inline toolbar action bars. Consider using other common navigation patterns instead.  
ActionBar.TabListener This interface was deprecated in API level 21. Action bar navigation modes are deprecated and not supported by inline toolbar action bars. Consider using other common navigation patterns instead.  
Application.ActivityLifecycleCallbacks  
Application.OnProvideAssistDataListener Callback interface for use with registerOnProvideAssistDataListener(Application.OnProvideAssistDataListener) and unregisterOnProvideAssistDataListener(Application.OnProvideAssistDataListener). 
AppOpsManager.OnOpChangedListener Callback for notification of changes to operation state. 
DatePickerDialog.OnDateSetListener The callback used to indicate the user is done filling in the date. 
FragmentBreadCrumbs.OnBreadCrumbClickListener Interface to intercept clicks on the bread crumbs. 
FragmentManager.BackStackEntry Representation of an entry on the fragment back stack, as created with FragmentTransaction.addToBackStack(). 
FragmentManager.OnBackStackChangedListener Interface to watch for changes to the back stack. 
KeyguardManager.OnKeyguardExitResult Callback passed to exitKeyguardSecurely(KeyguardManager.OnKeyguardExitResult) to notify caller of result. 
LoaderManager.LoaderCallbacks<D> Callback interface for a client to interact with the manager. 
Notification.Action.Extender Extender interface for use with extend(Notification.Action.Extender). 
Notification.Extender Extender interface for use with extend(Notification.Action.Extender). 
PendingIntent.OnFinished Callback interface for discovering when a send operation has completed. 
SearchManager.OnCancelListener See setOnCancelListener(SearchManager.OnCancelListener) for configuring your activity to monitor search UI state. 
SearchManager.OnDismissListener See setOnDismissListener(SearchManager.OnDismissListener) for configuring your activity to monitor search UI state. 
TimePickerDialog.OnTimeSetListener The callback interface used to indicate the user is done filling in the time (they clicked on the 'Done' button). 
UiAutomation.AccessibilityEventFilter Listener for filtering accessibility events. 
UiAutomation.OnAccessibilityEventListener Listener for observing the AccessibilityEvent stream. 

Classes

ActionBar A primary toolbar within the activity that may display the activity title, application-level navigation affordances, and other interactive items. 
ActionBar.LayoutParams Per-child layout information associated with action bar custom views. 
ActionBar.Tab This class was deprecated in API level 21. Action bar navigation modes are deprecated and not supported by inline toolbar action bars. Consider using other common navigation patterns instead.  
Activity An activity is a single, focused thing that the user can do. 
ActivityGroup This class was deprecated in API level 13. Use the new Fragment and FragmentManager APIs instead; these are also available on older platforms through the Android compatibility package.  
ActivityManager Interact with the overall activities running in the system. 
ActivityManager.AppTask The AppTask allows you to manage your own application's tasks. 
ActivityManager.MemoryInfo Information you can retrieve about the available memory through getMemoryInfo(ActivityManager.MemoryInfo). 
ActivityManager.ProcessErrorStateInfo Information you can retrieve about any processes that are in an error condition. 
ActivityManager.RecentTaskInfo Information you can retrieve about tasks that the user has most recently started or visited. 
ActivityManager.RunningAppProcessInfo Information you can retrieve about a running process. 
ActivityManager.RunningServiceInfo Information you can retrieve about a particular Service that is currently running in the system. 
ActivityManager.RunningTaskInfo Information you can retrieve about a particular task that is currently "running" in the system. 
ActivityManager.TaskDescription Information you can set and retrieve about the current activity within the recent task list. 
ActivityOptions Helper class for building an options Bundle that can be used with Context.startActivity(Intent, Bundle) and related methods. 
AlarmManager This class provides access to the system alarm services. 
AlarmManager.AlarmClockInfo An immutable description of an alarm clock. 
AlertDialog A subclass of Dialog that can display one, two or three buttons. 
AlertDialog.Builder  
AliasActivity Stub activity that launches another activity (and then finishes itself) based on information in its component's manifest meta-data. 
Application Base class for those who need to maintain global application state. 
ApplicationErrorReport Describes an application error. 
ApplicationErrorReport.AnrInfo Describes an application not responding error. 
ApplicationErrorReport.BatteryInfo Describes a battery usage report. 
ApplicationErrorReport.CrashInfo Describes an application crash. 
ApplicationErrorReport.RunningServiceInfo Describes a running service report. 
AppOpsManager API for interacting with "application operation" tracking. 
DatePickerDialog A simple dialog containing an DatePicker. 
Dialog Base class for Dialogs. 
DialogFragment A fragment that displays a dialog window, floating on top of its activity's window. 
DownloadManager The download manager is a system service that handles long-running HTTP downloads. 
DownloadManager.Query This class may be used to filter download manager queries. 
DownloadManager.Request This class contains all the information necessary to request a new download. 
ExpandableListActivity An activity that displays an expandable list of items by binding to a data source implementing the ExpandableListAdapter, and exposes event handlers when the user selects an item. 
Fragment A Fragment is a piece of an application's user interface or behavior that can be placed in an Activity. 
Fragment.SavedState State information that has been retrieved from a fragment instance through FragmentManager.saveFragmentInstanceState. 
FragmentBreadCrumbs This class was deprecated in API level 21. This widget is no longer supported.  
FragmentManager Interface for interacting with Fragment objects inside of an Activity

Developer Guides

For more information about using fragments, read the Fragments developer guide. 

FragmentTransaction API for performing a set of Fragment operations. 
Instrumentation Base class for implementing application instrumentation code. 
Instrumentation.ActivityMonitor Information about a particular kind of Intent that is being monitored. 
Instrumentation.ActivityResult Description of a Activity execution result to return to the original activity. 
IntentService IntentService is a base class for Services that handle asynchronous requests (expressed as Intents) on demand. 
KeyguardManager Class that can be used to lock and unlock the keyboard. 
KeyguardManager.KeyguardLock This class was deprecated in API level 13. Use FLAG_DISMISS_KEYGUARD and/or FLAG_SHOW_WHEN_LOCKED instead; this allows you to seamlessly hide the keyguard as your application moves in and out of the foreground and does not require that any special permissions be requested. Handle returned by newKeyguardLock(String) that allows you to disable / reenable the keyguard.  
LauncherActivity Displays a list of all activities which can be performed for a given intent. 
LauncherActivity.IconResizer Utility class to resize icons to match default icon size. 
LauncherActivity.ListItem An item in the list  
ListActivity An activity that displays a list of items by binding to a data source such as an array or Cursor, and exposes event handlers when the user selects an item. 
ListFragment A fragment that displays a list of items by binding to a data source such as an array or Cursor, and exposes event handlers when the user selects an item. 
LoaderManager Interface associated with an Activity or Fragment for managing one or more Loader instances associated with it. 
LocalActivityManager This class was deprecated in API level 13. Use the new Fragment and FragmentManager APIs instead; these are also available on older platforms through the Android compatibility package.  
MediaRouteActionProvider The media route action provider displays a media route button in the application's ActionBar to allow the user to select routes and to control the currently selected route. 
MediaRouteButton  
NativeActivity Convenience for implementing an activity that will be implemented purely in native code. 
Notification A class that represents how a persistent notification is to be presented to the user using the NotificationManager. 
Notification.Action Structure to encapsulate a named action that can be shown as part of this notification. 
Notification.Action.Builder Builder class for Notification.Action objects. 
Notification.Action.WearableExtender Wearable extender for notification actions. 
Notification.BigPictureStyle Helper class for generating large-format notifications that include a large image attachment. 
Notification.BigTextStyle Helper class for generating large-format notifications that include a lot of text. 
Notification.Builder Builder class for Notification objects. 
Notification.InboxStyle Helper class for generating large-format notifications that include a list of (up to 5) strings. 
Notification.MediaStyle Notification style for media playback notifications. 
Notification.Style An object that can apply a rich notification style to a Notification.Builder object. 
Notification.WearableExtender Helper class to add wearable extensions to notifications. 
NotificationManager Class to notify the user of events that happen. This is how you tell the user that something has happened in the background.  
PendingIntent A description of an Intent and target action to perform with it. 
Presentation Base class for presentations. 
ProgressDialog

A dialog showing a progress indicator and an optional text message or view. 

RemoteInput A RemoteInput object specifies input to be collected from a user to be passed along with an intent inside a PendingIntent that is sent. 
RemoteInput.Builder Builder class for RemoteInput objects. 
SearchableInfo Searchability meta-data for an activity. 
SearchManager This class provides access to the system search services. 
Service A Service is an application component representing either an application's desire to perform a longer-running operation while not interacting with the user or to supply functionality for other applications to use. 
SharedElementCallback Listener provided in setEnterSharedElementCallback(SharedElementCallback) and setExitSharedElementCallback(SharedElementCallback) as well as setEnterSharedElementCallback(SharedElementCallback) and setExitSharedElementCallback(SharedElementCallback) to monitor the Shared element transitions. 
TabActivity This class was deprecated in API level 13. New applications should use Fragments instead of this class; to continue to run on older devices, you can use the v4 support library which provides a version of the Fragment API that is compatible down to DONUT.  
TaskStackBuilder Utility class for constructing synthetic back stacks for cross-task navigation on Android 3.0 and newer. 
TimePickerDialog A dialog that prompts the user for the time of day using a TimePicker. 
UiAutomation Class for interacting with the device's UI by simulation user actions and introspection of the screen content. 
UiModeManager This class provides access to the system uimode services. 
WallpaperInfo This class is used to specify meta information of a wallpaper service. 
WallpaperManager Provides access to the system wallpaper. 

Exceptions

Fragment.InstantiationException Thrown by instantiate(Context, String, Bundle) when there is an instantiation failure. 
PendingIntent.CanceledException Exception thrown when trying to send through a PendingIntent that has been canceled or is otherwise no longer able to execute the request.