public abstract class

Service

extends ContextWrapper
implements ComponentCallbacks

java.lang.Object
↳	android.content.Context
	↳	android.content.ContextWrapper
		↳	android.app.Service

Known Direct Subclasses

AbstractInputMethodService, IntentService

Known Indirect Subclasses

InputMethodService

Class Overview

A Service is an application component that runs in the background, not interacting with the user, for an indefinite period of time. Each service class must have a corresponding <service> declaration in its package's AndroidManifest.xml. Services can be started with Context.startService() and Context.bindService().

Note that services, like other application objects, run in the main thread of their hosting process. This means that, if your service is going to do any CPU intensive (such as MP3 playback) or blocking (such as networking) operations, it should spawn its own thread in which to do that work. More information on this can be found in Application Fundamentals: Processes and Threads.

The Service class is an important part of an application's overall lifecycle.

Topics covered here:

Service Lifecycle
Permissions
Process Lifecycle

Service Lifecycle

There are two reasons that a service can be run by the system. If someone calls Context.startService() then the system will retrieve the service (creating it and calling its onCreate() method if needed) and then call its onStart(Intent, int) method with the arguments supplied by the client. The service will at this point continue running until Context.stopService() or stopSelf() is called. Note that multiple calls to Context.startService() do not nest (though they do result in multiple corresponding calls to onStart()), so no matter how many times it is started a service will be stopped once Context.stopService() or stopSelf() is called.

Clients can also use Context.bindService() to obtain a persistent connection to a service. This likewise creates the service if it is not already running (calling onCreate() while doing so), but does not call onStart(). The client will receive the IBinder object that the service returns from its onBind(Intent) method, allowing the client to then make calls back to the service. The service will remain running as long as the connection is established (whether or not the client retains a reference on the service's IBinder). Usually the IBinder returned is for a complex interface that has been written in aidl.

A service can be both started and have connections bound to it. In such a case, the system will keep the service running as long as either it is started or there are one or more connections to it with the Context.BIND_AUTO_CREATE flag. Once neither of these situations hold, the service's onDestroy() method is called and the service is effectively terminated. All cleanup (stopping threads, unregistering receivers) should be complete upon returning from onDestroy().

Permissions

Global access to a service can be enforced when it is declared in its manifest's <service> tag. By doing so, other applications will need to declare a corresponding <uses-permission> element in their own manifest to be able to start, stop, or bind to the service.

In addition, a service can protect individual IPC calls into it with permissions, by calling the checkCallingPermission(String) method before executing the implementation of that call.

See the Security and Permissions document for more information on permissions and security in general.

Process Lifecycle

The Android system will attempt to keep the process hosting a service around as long as the service has been started or has clients bound to it. When running low on memory and needing to kill existing processes, the priority of a process hosting the service will be the higher of the following possibilities:

If the service is currently executing code in its onCreate(), onStart(), or onDestroy() methods, then the hosting process will be a foreground process to ensure this code can execute without being killed.
If the service has been started, then its hosting process is considered to be less important than any processes that are currently visible to the user on-screen, but more important than any process not visible. Because only a few processes are generally visible to the user, this means that the service should not be killed except in extreme low memory conditions.
If there are clients bound to the service, then the service's hosting process is never less important than the most important client. That is, if one of its clients is visible to the user, then the service itself is considered to be visible.

Note this means that most of the time your service is running, it may be killed by the system if it is under heavy memory pressure. If this happens, the system will later try to restart the service. An important consequence of this is that if you implement onStart() to schedule work to be done asynchronously or in another thread, then you may want to write information about that work into persistent storage during the onStart() call so that it does not get lost if the service later gets killed.

Other application components running in the same process as the service (such as an Activity) can, of course, increase the importance of the overall process beyond just the importance of the service itself.

Summary

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Inherited Constants

From class android.content.Context

Public Constructors
	Service()

Public Methods
final Application	getApplication() Return the application that owns this service.
abstract IBinder	onBind(Intent intent) Return the communication channel to the service.
void	onConfigurationChanged(Configuration newConfig) Called by the system when the device configuration changes while your component is running.
void	onCreate() Called by the system when the service is first created.
void	onDestroy() Called by the system to notify a Service that it is no longer used and is being removed.
void	onLowMemory() This is called when the overall system is running low on memory, and would like actively running process to try to tighten their belt.
void	onRebind(Intent intent) Called when new clients have connected to the service, after it had previously been notified that all had disconnected in its onUnbind(Intent).
void	onStart(Intent intent, int startId) Called by the system every time a client explicitly starts the service by calling startService(Intent), providing the arguments it supplied and a unique integer token representing the start request.
boolean	onUnbind(Intent intent) Called when all clients have disconnected from a particular interface published by the service.
final void	setForeground(boolean isForeground) Control whether this service is considered to be a foreground service.
final void	stopSelf() Stop the service, if it was previously started.
final void	stopSelf(int startId) Old version of stopSelfResult(int) that doesn't return a result.
final boolean	stopSelfResult(int startId) Stop the service if the most recent time it was started was `startId`.

Protected Methods
void	dump(FileDescriptor fd, PrintWriter writer, String[] args) Print the Service's state into the given stream.
void	finalize() Is called before the object's memory is being reclaimed by the VM.

[Expand]

Inherited Methods

From class android.content.ContextWrapper

From class android.content.Context

abstract boolean	bindService(Intent service, ServiceConnection conn, int flags) Connect to an application service, creating it if needed.
abstract int	checkCallingOrSelfPermission(String permission) Determine whether the calling process of an IPC or you have been granted a particular permission.
abstract int	checkCallingOrSelfUriPermission(Uri uri, int modeFlags) Determine whether the calling process of an IPC or you has been granted permission to access a specific URI.
abstract int	checkCallingPermission(String permission) Determine whether the calling process of an IPC you are handling has been granted a particular permission.
abstract int	checkCallingUriPermission(Uri uri, int modeFlags) Determine whether the calling process and user ID has been granted permission to access a specific URI.
abstract int	checkPermission(String permission, int pid, int uid) Determine whether the given permission is allowed for a particular process and user ID running in the system.
abstract int	checkUriPermission(Uri uri, int pid, int uid, int modeFlags) Determine whether a particular process and user ID has been granted permission to access a specific URI.
abstract int	checkUriPermission(Uri uri, String readPermission, String writePermission, int pid, int uid, int modeFlags) Check both a Uri and normal permission.
abstract void	clearWallpaper() Remove any currently set wallpaper, reverting to the system's default wallpaper.
abstract Context	createPackageContext(String packageName, int flags) Return a new Context object for the given application name.
abstract String[]	databaseList() Returns an array of strings naming the private databases associated with this Context's application package.
abstract boolean	deleteDatabase(String name) Delete an existing private SQLiteDatabase associated with this Context's application package.
abstract boolean	deleteFile(String name) Delete the given private file associated with this Context's application package.
abstract void	enforceCallingOrSelfPermission(String permission, String message) If neither you nor the calling process of an IPC you are handling has been granted a particular permission, throw a SecurityException.
abstract void	enforceCallingOrSelfUriPermission(Uri uri, int modeFlags, String message) If the calling process of an IPC or you has not been granted permission to access a specific URI, throw SecurityException.
abstract void	enforceCallingPermission(String permission, String message) If the calling process of an IPC you are handling has not been granted a particular permission, throw a SecurityException.
abstract void	enforceCallingUriPermission(Uri uri, int modeFlags, String message) If the calling process and user ID has not been granted permission to access a specific URI, throw SecurityException.
abstract void	enforcePermission(String permission, int pid, int uid, String message) If the given permission is not allowed for a particular process and user ID running in the system, throw a SecurityException.
abstract void	enforceUriPermission(Uri uri, int pid, int uid, int modeFlags, String message) If a particular process and user ID has not been granted permission to access a specific URI, throw SecurityException.
abstract void	enforceUriPermission(Uri uri, String readPermission, String writePermission, int pid, int uid, int modeFlags, String message) Enforce both a Uri and normal permission.
abstract String[]	fileList() Returns an array of strings naming the private files associated with this Context's application package.
abstract Context	getApplicationContext() Return the context of the single, global Application object of the current process.
abstract AssetManager	getAssets() Return an AssetManager instance for your application's package.
abstract File	getCacheDir() Returns the absolute path to the application specific cache directory on the filesystem.
abstract ClassLoader	getClassLoader() Return a class loader you can use to retrieve classes in this package.
abstract ContentResolver	getContentResolver() Return a ContentResolver instance for your application's package.
abstract File	getDatabasePath(String name) Returns the absolute path on the filesystem where a database created with openOrCreateDatabase(String, int, SQLiteDatabase.CursorFactory) is stored.
abstract File	getDir(String name, int mode) Retrieve, creating if needed, a new directory in which the application can place its own custom data files.
abstract File	getFileStreamPath(String name) Returns the absolute path on the filesystem where a file created with openFileOutput(String, int) is stored.
abstract File	getFilesDir() Returns the absolute path to the directory on the filesystem where files created with openFileOutput(String, int) are stored.
abstract Looper	getMainLooper() Return the Looper for the main thread of the current process.
abstract PackageManager	getPackageManager() Return PackageManager instance to find global package information.
abstract String	getPackageName() Return the name of this application's package.
abstract Resources	getResources() Return a Resources instance for your application's package.
abstract SharedPreferences	getSharedPreferences(String name, int mode) Retrieve and hold the contents of the preferences file 'name', returning a SharedPreferences through which you can retrieve and modify its values.
final String	getString(int resId, Object... formatArgs) Return a localized formatted string from the application's package's default string table, substituting the format arguments as defined in Formatter and format(String, Object...).
final String	getString(int resId) Return a localized string from the application's package's default string table.
abstract Object	getSystemService(String name) Return the handle to a system-level service by name.
final CharSequence	getText(int resId) Return a localized, styled CharSequence from the application's package's default string table.
abstract Resources.Theme	getTheme() Return the Theme object associated with this Context.
abstract Drawable	getWallpaper() Like peekWallpaper(), but always returns a valid Drawable.
abstract int	getWallpaperDesiredMinimumHeight() Returns the desired minimum height for the wallpaper.
abstract int	getWallpaperDesiredMinimumWidth() Returns the desired minimum width for the wallpaper.
abstract void	grantUriPermission(String toPackage, Uri uri, int modeFlags) Grant permission to access a specific Uri to another package, regardless of whether that package has general permission to access the Uri's content provider.
final TypedArray	obtainStyledAttributes(int resid, int[] attrs) Retrieve styled attribute information in this Context's theme.
final TypedArray	obtainStyledAttributes(AttributeSet set, int[] attrs, int defStyleAttr, int defStyleRes) Retrieve styled attribute information in this Context's theme.
final TypedArray	obtainStyledAttributes(int[] attrs) Retrieve styled attribute information in this Context's theme.
final TypedArray	obtainStyledAttributes(AttributeSet set, int[] attrs) Retrieve styled attribute information in this Context's theme.
abstract FileInputStream	openFileInput(String name) Open a private file associated with this Context's application package for reading.
abstract FileOutputStream	openFileOutput(String name, int mode) Open a private file associated with this Context's application package for writing.
abstract SQLiteDatabase	openOrCreateDatabase(String name, int mode, SQLiteDatabase.CursorFactory factory) Open a new private SQLiteDatabase associated with this Context's application package.
abstract Drawable	peekWallpaper() Retrieve the current system wallpaper.
abstract Intent	registerReceiver(BroadcastReceiver receiver, IntentFilter filter, String broadcastPermission, Handler scheduler) Register to receive intent broadcasts, to run in the context of `scheduler`.
abstract Intent	registerReceiver(BroadcastReceiver receiver, IntentFilter filter) Register a BroadcastReceiver to be run in the main activity thread.
abstract void	removeStickyBroadcast(Intent intent) Remove the data previously sent with sendStickyBroadcast(Intent), so that it is as if the sticky broadcast had never happened.
abstract void	revokeUriPermission(Uri uri, int modeFlags) Remove all permissions to access a particular content provider Uri that were previously added with grantUriPermission(String, Uri, int).
abstract void	sendBroadcast(Intent intent) Broadcast the given intent to all interested BroadcastReceivers.
abstract void	sendBroadcast(Intent intent, String receiverPermission) Broadcast the given intent to all interested BroadcastReceivers, allowing an optional required permission to be enforced.
abstract void	sendOrderedBroadcast(Intent intent, String receiverPermission, BroadcastReceiver resultReceiver, Handler scheduler, int initialCode, String initialData, Bundle initialExtras) Version of sendBroadcast(Intent) that allows you to receive data back from the broadcast.
abstract void	sendOrderedBroadcast(Intent intent, String receiverPermission) Broadcast the given intent to all interested BroadcastReceivers, delivering them one at a time to allow more preferred receivers to consume the broadcast before it is delivered to less preferred receivers.
abstract void	sendStickyBroadcast(Intent intent) Perform a sendBroadcast(Intent) that is "sticky," meaning the Intent you are sending stays around after the broadcast is complete, so that others can quickly retrieve that data through the return value of registerReceiver(BroadcastReceiver, IntentFilter).
abstract void	setTheme(int resid) Set the base theme for this context.
abstract void	setWallpaper(InputStream data) Change the current system wallpaper to a specific byte stream.
abstract void	setWallpaper(Bitmap bitmap) Change the current system wallpaper to a bitmap.
abstract void	startActivity(Intent intent) Launch a new activity.
abstract boolean	startInstrumentation(ComponentName className, String profileFile, Bundle arguments) Start executing an Instrumentation class.
abstract ComponentName	startService(Intent service) Request that a given application service be started.
abstract boolean	stopService(Intent service) Request that a given application service be stopped.
abstract void	unbindService(ServiceConnection conn) Disconnect from an application service.
abstract void	unregisterReceiver(BroadcastReceiver receiver) Unregister a previously registered BroadcastReceiver.

From class java.lang.Object

Object	clone() Creates and returns a copy of this `Object`.
boolean	equals(Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Is called before the object's memory is being reclaimed by the VM.
final Class<? extends Object>	getClass() Returns the unique instance of Class which represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait(long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.

From interface android.content.ComponentCallbacks

Public Constructors

public Service ()

Public Methods

public final Application getApplication ()

Return the application that owns this service.

public abstract IBinder onBind (Intent intent)

Return the communication channel to the service. May return null if clients can not bind to the service. The returned IBinder is usually for a complex interface that has been described using aidl.

Note that unlike other application components, calls on to the IBinder interface returned here may not happen on the main thread of the process. More information about this can be found in Application Fundamentals: Processes and Threads.

Parameters

intent	The Intent that was used to bind to this service, as given to Context.bindService. Note that any extras that were included with the Intent at that point will not be seen here.

Returns

Return an IBinder through which clients can call on to the service.

public void onConfigurationChanged (Configuration newConfig)

Called by the system when the device configuration changes while your component is running. Note that, unlike activities, other components are never restarted when a configuration changes: they must always deal with the results of the change, such as by re-retrieving resources.

At the time that this function has been called, your Resources object will have been updated to return resource values matching the new configuration.

Parameters

newConfig	The new device configuration.

public void onCreate ()

Called by the system when the service is first created. Do not call this method directly.

public void onDestroy ()

Called by the system to notify a Service that it is no longer used and is being removed. The service should clean up an resources it holds (threads, registered receivers, etc) at this point. Upon return, there will be no more calls in to this Service object and it is effectively dead. Do not call this method directly.

public void onLowMemory ()

This is called when the overall system is running low on memory, and would like actively running process to try to tighten their belt. While the exact point at which this will be called is not defined, generally it will happen around the time all background process have been killed, that is before reaching the point of killing processes hosting service and foreground UI that we would like to avoid killing.

Applications that want to be nice can implement this method to release any caches or other unnecessary resources they may be holding on to. The system will perform a gc for you after returning from this method.

public void onRebind (Intent intent)

Called when new clients have connected to the service, after it had previously been notified that all had disconnected in its onUnbind(Intent). This will only be called if the implementation of onUnbind(Intent) was overridden to return true.

Parameters

intent	The Intent that was used to bind to this service, as given to Context.bindService. Note that any extras that were included with the Intent at that point will not be seen here.

public void onStart (Intent intent, int startId)

Called by the system every time a client explicitly starts the service by calling startService(Intent), providing the arguments it supplied and a unique integer token representing the start request. Do not call this method directly.

Parameters

intent	The Intent supplied to startService(Intent), as given.
startId	A unique integer representing this specific request to start. Use with stopSelfResult(int).

public boolean onUnbind (Intent intent)

Called when all clients have disconnected from a particular interface published by the service. The default implementation does nothing and returns false.

Parameters

intent	The Intent that was used to bind to this service, as given to Context.bindService. Note that any extras that were included with the Intent at that point will not be seen here.

Returns

Return true if you would like to have the service's onRebind(Intent) method later called when new clients bind to it.

public final void setForeground (boolean isForeground)

Control whether this service is considered to be a foreground service. By default services are background, meaning that if the system needs to kill them to reclaim more memory (such as to display a large page in a web browser), they can be killed without too much harm. You can set this flag if killing your service would be disruptive to the user: such as if your service is performing background music playback, so the user would notice if their music stopped playing.

Parameters

isForeground	Determines whether this service is considered to be foreground (true) or background (false).

public final void stopSelf ()

Stop the service, if it was previously started. This is the same as calling stopService(Intent) for this particular service.

public final void stopSelf (int startId)

Old version of stopSelfResult(int) that doesn't return a result.

public final boolean stopSelfResult (int startId)

Stop the service if the most recent time it was started was startId. This is the same as calling stopService(Intent) for this particular service but allows you to safely avoid stopping if there is a start request from a client that you haven't yet seen in onStart(Intent, int).

Parameters

startId	The most recent start identifier received in onStart(Intent, int).

Returns

Returns true if the startId matches the last start request and the service will be stopped, else false.

Protected Methods

protected void dump (FileDescriptor fd, PrintWriter writer, String[] args)

Print the Service's state into the given stream. This gets invoked if you run "adb shell dumpsys activity service ". This is distinct from "dumpsys ", which only works for named system services and which invokes the dump(FileDescriptor, String[]) method on the IBinder interface registered with ServiceManager.

Parameters

fd	The raw file descriptor that the dump is being sent to.
writer	The PrintWriter to which you should dump your state. This will be closed for you after you return.
args	additional arguments to the dump request.

protected void finalize ()

Is called before the object's memory is being reclaimed by the VM. This can only happen once the VM has detected, during a run of the garbage collector, that the object is no longer reachable by any thread of the running application.

The method can be used to free system resources or perform other cleanup before the object is garbage collected. The default implementation of the method is empty, which is also expected by the VM, but subclasses can override finalize() as required. Uncaught exceptions which are thrown during the execution of this method cause it to terminate immediately but are otherwise ignored.

Note that the VM does guarantee that finalize() is called at most once for any object, but it doesn't guarantee when (if at all) finalize() will be called. For example, object B's finalize() can delay the execution of object A's finalize() method and therefore it can delay the reclamation of A's memory. To be safe, use a ReferenceQueue, because it provides more control over the way the VM deals with references during garbage collection.

Throws

Throwable

Interfaces

Classes

Exceptions

Service

Class Overview

Service Lifecycle

Permissions

Process Lifecycle

Summary

Public Constructors

public Service ()

Public Methods

public final Application getApplication ()

public abstract IBinder onBind (Intent intent)

Parameters

Returns

public void onConfigurationChanged (Configuration newConfig)

Parameters

public void onCreate ()

public void onDestroy ()

public void onLowMemory ()

public void onRebind (Intent intent)

Parameters

public void onStart (Intent intent, int startId)

Parameters

See Also

public boolean onUnbind (Intent intent)

Parameters

Returns

public final void setForeground (boolean isForeground)

Parameters

public final void stopSelf ()

See Also

public final void stopSelf (int startId)

See Also

public final boolean stopSelfResult (int startId)

Parameters

Returns

See Also

Protected Methods

protected void dump (FileDescriptor fd, PrintWriter writer, String[] args)

Parameters

protected void finalize ()

Throws