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  • 22/10/2021
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Added in API level 1
Summary: Constants | Inherited Constants | Ctors | Methods | Protected Methods | Inherited Methods

Service

public abstract class Service
extends ContextWrapper implements ComponentCallbacks2

java.lang.Object android.content.Context android.content.ContextWrapper android.app.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. 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 Processes and Threads. The JobIntentService class is available as a standard implementation of Service that has its own thread where it schedules its work to be done.

Topics covered here:

  1. What is a Service?
  2. Service Lifecycle
  3. Permissions
  4. Process Lifecycle
  5. Local Service Sample
  6. Remote Messenger Service Sample

Developer Guides

For a detailed discussion about how to create services, read the Services developer guide.

What is a Service?

Most confusion about the Service class actually revolves around what it is not:

  • A Service is not a separate process. The Service object itself does not imply it is running in its own process; unless otherwise specified, it runs in the same process as the application it is part of.
  • A Service is not a thread. It is not a means itself to do work off of the main thread (to avoid Application Not Responding errors).

Thus a Service itself is actually very simple, providing two main features:

  • A facility for the application to tell the system about something it wants to be doing in the background (even when the user is not directly interacting with the application). This corresponds to calls to Context.startService(), which ask the system to schedule work for the service, to be run until the service or someone else explicitly stop it.
  • A facility for an application to expose some of its functionality to other applications. This corresponds to calls to Context.bindService(), which allows a long-standing connection to be made to the service in order to interact with it.

When a Service component is actually created, for either of these reasons, all that the system actually does is instantiate the component and call its onCreate() and any other appropriate callbacks on the main thread. It is up to the Service to implement these with the appropriate behavior, such as creating a secondary thread in which it does its work.

Note that because Service itself is so simple, you can make your interaction with it as simple or complicated as you want: from treating it as a local Java object that you make direct method calls on (as illustrated by Local Service Sample), to providing a full remoteable interface using AIDL.

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 onStartCommand(Intent, int, 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 onStartCommand()), so no matter how many times it is started a service will be stopped once Context.stopService() or stopSelf() is called; however, services can use their stopSelf(int) method to ensure the service is not stopped until started intents have been processed.

For started services, there are two additional major modes of operation they can decide to run in, depending on the value they return from onStartCommand(): START_STICKY is used for services that are explicitly started and stopped as needed, while START_NOT_STICKY or START_REDELIVER_INTENT are used for services that should only remain running while processing any commands sent to them. See the linked documentation for more detail on the semantics.

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 onStartCommand(). 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.

As of Build.VERSION_CODES.GINGERBREAD, when using Context.startService(Intent), you can also set Intent.FLAG_GRANT_READ_URI_PERMISSION and/or Intent.FLAG_GRANT_WRITE_URI_PERMISSION on the Intent. This will grant the Service temporary access to the specific URIs in the Intent. Access will remain until the Service has called stopSelf(int) for that start command or a later one, or until the Service has been completely stopped. This works for granting access to the other apps that have not requested the permission protecting the Service, or even when the Service is not exported at all.

In addition, a service can protect individual IPC calls into it with permissions, by calling the ContextWrapper.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(), onStartCommand(), 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 low memory conditions. However, since the user is not directly aware of a background service, in that state it is considered a valid candidate to kill, and you should be prepared for this to happen. In particular, long-running services will be increasingly likely to kill and are guaranteed to be killed (and restarted if appropriate) if they remain started long enough.

  • 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. The way a client's importance impacts the service's importance can be adjusted through Context#BIND_ABOVE_CLIENT, Context#BIND_ALLOW_OOM_MANAGEMENT, Context#BIND_WAIVE_PRIORITY, Context#BIND_IMPORTANT, and Context#BIND_ADJUST_WITH_ACTIVITY.

  • A started service can use the startForeground(int, android.app.Notification) API to put the service in a foreground state, where the system considers it to be something the user is actively aware of and thus not a candidate for killing when low on memory. (It is still theoretically possible for the service to be killed under extreme memory pressure from the current foreground application, but in practice this should not be a concern.)

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 onStartCommand() to schedule work to be done asynchronously or in another thread, then you may want to use START_FLAG_REDELIVERY to have the system re-deliver an Intent for you so that it does not get lost if your service is killed while processing it.

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.

Local Service Sample

One of the most common uses of a Service is as a secondary component running alongside other parts of an application, in the same process as the rest of the components. All components of an .apk run in the same process unless explicitly stated otherwise, so this is a typical situation.

When used in this way, by assuming the components are in the same process, you can greatly simplify the interaction between them: clients of the service can simply cast the IBinder they receive from it to a concrete class published by the service.

An example of this use of a Service is shown here. First is the Service itself, publishing a custom class when bound:

public class LocalService extends Service { private NotificationManager mNM; // Unique Identification Number for the Notification. // We use it on Notification start, and to cancel it. private int NOTIFICATION = R.string.local_service_started; /** * Class for clients to access. Because we know this service always * runs in the same process as its clients, we don't need to deal with * IPC. */ public class LocalBinder extends Binder { LocalService getService() { return LocalService.this; } } @Override public void onCreate() { mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE); // Display a notification about us starting. We put an icon in the status bar. showNotification(); } @Override public int onStartCommand(Intent intent, int flags, int startId) { Log.i("LocalService", "Received start id " + startId + ": " + intent); return START_NOT_STICKY; } @Override public void onDestroy() { // Cancel the persistent notification. mNM.cancel(NOTIFICATION); // Tell the user we stopped. Toast.makeText(this, R.string.local_service_stopped, Toast.LENGTH_SHORT).show(); } @Override public IBinder onBind(Intent intent) { return mBinder; } // This is the object that receives interactions from clients. See // RemoteService for a more complete example. private final IBinder mBinder = new LocalBinder(); /** * Show a notification while this service is running. */ private void showNotification() { // In this sample, we'll use the same text for the ticker and the expanded notification CharSequence text = getText(R.string.local_service_started); // The PendingIntent to launch our activity if the user selects this notification PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, LocalServiceActivities.Controller.class), 0); // Set the info for the views that show in the notification panel. Notification notification = new Notification.Builder(this) .setSmallIcon(R.drawable.stat_sample) // the status icon .setTicker(text) // the status text .setWhen(System.currentTimeMillis()) // the time stamp .setContentTitle(getText(R.string.local_service_label)) // the label of the entry .setContentText(text) // the contents of the entry .setContentIntent(contentIntent) // The intent to send when the entry is clicked .build(); // Send the notification. mNM.notify(NOTIFICATION, notification); } }

With that done, one can now write client code that directly accesses the running service, such as:

/** * Example of binding and unbinding to the local service. * bind to, receiving an object through which it can communicate with the service. * * Note that this is implemented as an inner class only keep the sample * all together; typically this code would appear in some separate class. */ public static class Binding extends Activity { // Don't attempt to unbind from the service unless the client has received some // information about the service's state. private boolean mShouldUnbind; // To invoke the bound service, first make sure that this value // is not null. private LocalService mBoundService; private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // This is called when the connection with the service has been // established, giving us the service object we can use to // interact with the service. Because we have bound to a explicit // service that we know is running in our own process, we can // cast its IBinder to a concrete class and directly access it. mBoundService = ((LocalService.LocalBinder)service).getService(); // Tell the user about this for our demo. Toast.makeText(Binding.this, R.string.local_service_connected, Toast.LENGTH_SHORT).show(); } public void onServiceDisconnected(ComponentName className) { // This is called when the connection with the service has been // unexpectedly disconnected -- that is, its process crashed. // Because it is running in our same process, we should never // see this happen. mBoundService = null; Toast.makeText(Binding.this, R.string.local_service_disconnected, Toast.LENGTH_SHORT).show(); } }; void doBindService() { // Attempts to establish a connection with the service. We use an // explicit class name because we want a specific service // implementation that we know will be running in our own process // (and thus won't be supporting component replacement by other // applications). if (bindService(new Intent(Binding.this, LocalService.class), mConnection, Context.BIND_AUTO_CREATE)) { mShouldUnbind = true; } else { Log.e("MY_APP_TAG", "Error: The requested service doesn't " + "exist, or this client isn't allowed access to it."); } } void doUnbindService() { if (mShouldUnbind) { // Release information about the service's state. unbindService(mConnection); mShouldUnbind = false; } } @Override protected void onDestroy() { super.onDestroy(); doUnbindService(); }

Remote Messenger Service Sample

If you need to be able to write a Service that can perform complicated communication with clients in remote processes (beyond simply the use of Context.startService to send commands to it), then you can use the Messenger class instead of writing full AIDL files.

An example of a Service that uses Messenger as its client interface is shown here. First is the Service itself, publishing a Messenger to an internal Handler when bound:

public class MessengerService extends Service { /** For showing and hiding our notification. */ NotificationManager mNM; /** Keeps track of all current registered clients. */ ArrayList<Messenger> mClients = new ArrayList<Messenger>(); /** Holds last value set by a client. */ int mValue = 0; /** * Command to the service to register a client, receiving callbacks * from the service. The Message's replyTo field must be a Messenger of * the client where callbacks should be sent. */ static final int MSG_REGISTER_CLIENT = 1; /** * Command to the service to unregister a client, ot stop receiving callbacks * from the service. The Message's replyTo field must be a Messenger of * the client as previously given with MSG_REGISTER_CLIENT. */ static final int MSG_UNREGISTER_CLIENT = 2; /** * Command to service to set a new value. This can be sent to the * service to supply a new value, and will be sent by the service to * any registered clients with the new value. */ static final int MSG_SET_VALUE = 3; /** * Handler of incoming messages from clients. */ class IncomingHandler extends Handler { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_REGISTER_CLIENT: mClients.add(msg.replyTo); break; case MSG_UNREGISTER_CLIENT: mClients.remove(msg.replyTo); break; case MSG_SET_VALUE: mValue = msg.arg1; for (int i=mClients.size()-1; i>=0; i--) { try { mClients.get(i).send(Message.obtain(null, MSG_SET_VALUE, mValue, 0)); } catch (RemoteException e) { // The client is dead. Remove it from the list; // we are going through the list from back to front // so this is safe to do inside the loop. mClients.remove(i); } } break; default: super.handleMessage(msg); } } } /** * Target we publish for clients to send messages to IncomingHandler. */ final Messenger mMessenger = new Messenger(new IncomingHandler()); @Override public void onCreate() { mNM = (NotificationManager)getSystemService(NOTIFICATION_SERVICE); // Display a notification about us starting. showNotification(); } @Override public void onDestroy() { // Cancel the persistent notification. mNM.cancel(R.string.remote_service_started); // Tell the user we stopped. Toast.makeText(this, R.string.remote_service_stopped, Toast.LENGTH_SHORT).show(); } /** * When binding to the service, we return an interface to our messenger * for sending messages to the service. */ @Override public IBinder onBind(Intent intent) { return mMessenger.getBinder(); } /** * Show a notification while this service is running. */ private void showNotification() { // In this sample, we'll use the same text for the ticker and the expanded notification CharSequence text = getText(R.string.remote_service_started); // The PendingIntent to launch our activity if the user selects this notification PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(this, Controller.class), 0); // Set the info for the views that show in the notification panel. Notification notification = new Notification.Builder(this) .setSmallIcon(R.drawable.stat_sample) // the status icon .setTicker(text) // the status text .setWhen(System.currentTimeMillis()) // the time stamp .setContentTitle(getText(R.string.local_service_label)) // the label of the entry .setContentText(text) // the contents of the entry .setContentIntent(contentIntent) // The intent to send when the entry is clicked .build(); // Send the notification. // We use a string id because it is a unique number. We use it later to cancel. mNM.notify(R.string.remote_service_started, notification); } }

If we want to make this service run in a remote process (instead of the standard one for its .apk), we can use android:process in its manifest tag to specify one:

<service android:name=".app.MessengerService" android:process=":remote" />

Note that the name "remote" chosen here is arbitrary, and you can use other names if you want additional processes. The ':' prefix appends the name to your package's standard process name.

With that done, clients can now bind to the service and send messages to it. Note that this allows clients to register with it to receive messages back as well:

/** * Example of binding and unbinding to the remote service. * This demonstrates the implementation of a service which the client will * bind to, interacting with it through an aidl interface. * * Note that this is implemented as an inner class only keep the sample * all together; typically this code would appear in some separate class. */ public static class Binding extends Activity { /** Messenger for communicating with service. */ Messenger mService = null; /** Flag indicating whether we have called bind on the service. */ boolean mIsBound; /** Some text view we are using to show state information. */ TextView mCallbackText; /** * Handler of incoming messages from service. */ class IncomingHandler extends Handler { @Override public void handleMessage(Message msg) { switch (msg.what) { case MessengerService.MSG_SET_VALUE: mCallbackText.setText("Received from service: " + msg.arg1); break; default: super.handleMessage(msg); } } } /** * Target we publish for clients to send messages to IncomingHandler. */ final Messenger mMessenger = new Messenger(new IncomingHandler()); /** * Class for interacting with the main interface of the service. */ private ServiceConnection mConnection = new ServiceConnection() { public void onServiceConnected(ComponentName className, IBinder service) { // This is called when the connection with the service has been // established, giving us the service object we can use to // interact with the service. We are communicating with our // service through an IDL interface, so get a client-side // representation of that from the raw service object. mService = new Messenger(service); mCallbackText.setText("Attached."); // We want to monitor the service for as long as we are // connected to it. try { Message msg = Message.obtain(null, MessengerService.MSG_REGISTER_CLIENT); msg.replyTo = mMessenger; mService.send(msg); // Give it some value as an example. msg = Message.obtain(null, MessengerService.MSG_SET_VALUE, this.hashCode(), 0); mService.send(msg); } catch (RemoteException e) { // In this case the service has crashed before we could even // do anything with it; we can count on soon being // disconnected (and then reconnected if it can be restarted) // so there is no need to do anything here. } // As part of the sample, tell the user what happened. Toast.makeText(Binding.this, R.string.remote_service_connected, Toast.LENGTH_SHORT).show(); } public void onServiceDisconnected(ComponentName className) { // This is called when the connection with the service has been // unexpectedly disconnected -- that is, its process crashed. mService = null; mCallbackText.setText("Disconnected."); // As part of the sample, tell the user what happened. Toast.makeText(Binding.this, R.string.remote_service_disconnected, Toast.LENGTH_SHORT).show(); } }; void doBindService() { // Establish a connection with the service. We use an explicit // class name because there is no reason to be able to let other // applications replace our component. bindService(new Intent(Binding.this, MessengerService.class), mConnection, Context.BIND_AUTO_CREATE); mIsBound = true; mCallbackText.setText("Binding."); } void doUnbindService() { if (mIsBound) { // If we have received the service, and hence registered with // it, then now is the time to unregister. if (mService != null) { try { Message msg = Message.obtain(null, MessengerService.MSG_UNREGISTER_CLIENT); msg.replyTo = mMessenger; mService.send(msg); } catch (RemoteException e) { // There is nothing special we need to do if the service // has crashed. } } // Detach our existing connection. unbindService(mConnection); mIsBound = false; mCallbackText.setText("Unbinding."); } }

Summary

Constants

int START_CONTINUATION_MASK

Bits returned by onStartCommand(Intent, int, int) describing how to continue the service if it is killed.

int START_FLAG_REDELIVERY

This flag is set in onStartCommand(Intent, int, int) if the Intent is a re-delivery of a previously delivered intent, because the service had previously returned START_REDELIVER_INTENT but had been killed before calling stopSelf(int) for that Intent.

int START_FLAG_RETRY

This flag is set in onStartCommand(Intent, int, int) if the Intent is a retry because the original attempt never got to or returned from onStartCommand(android.content.Intent, int, int).

int START_NOT_STICKY

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), and there are no new start intents to deliver to it, then take the service out of the started state and don't recreate until a future explicit call to Context.startService(Intent).

int START_REDELIVER_INTENT

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then it will be scheduled for a restart and the last delivered Intent re-delivered to it again via onStartCommand(Intent, int, int).

int START_STICKY

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then leave it in the started state but don't retain this delivered intent.

int START_STICKY_COMPATIBILITY

Constant to return from onStartCommand(Intent, int, int): compatibility version of START_STICKY that does not guarantee that onStartCommand(Intent, int, int) will be called again after being killed.

int STOP_FOREGROUND_DETACH

Flag for stopForeground(int): if set, the notification previously provided to startForeground(int, Notification) will be detached from the service.

int STOP_FOREGROUND_REMOVE

Flag for stopForeground(int): if set, the notification previously provided to startForeground(int, Notification) will be removed.

Inherited constants

Public constructors

Service()

Public methods

final Application getApplication()

Return the application that owns this service.

final int getForegroundServiceType()

If the service has become a foreground service by calling startForeground(int, android.app.Notification) or startForeground(int, android.app.Notification, int), getForegroundServiceType() returns the current foreground service type.

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 actively running processes should trim their memory usage.

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)

This method was deprecated in API level 15. Implement onStartCommand(android.content.Intent, int, int) instead.

int onStartCommand(Intent intent, int flags, int startId)

Called by the system every time a client explicitly starts the service by calling Context.startService(Intent), providing the arguments it supplied and a unique integer token representing the start request.

void onTaskRemoved(Intent rootIntent)

This is called if the service is currently running and the user has removed a task that comes from the service's application.

void onTrimMemory(int level)

Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process.

boolean onUnbind(Intent intent)

Called when all clients have disconnected from a particular interface published by the service.

final void startForeground(int id, Notification notification)

If your service is started (running through Context#startService(Intent)), then also make this service run in the foreground, supplying the ongoing notification to be shown to the user while in this state.

final void startForeground(int id, Notification notification, int foregroundServiceType)

An overloaded version of startForeground(int, android.app.Notification) with additional foregroundServiceType parameter.

final void stopForeground(int flags)

Remove this service from foreground state, allowing it to be killed if more memory is needed.

final void stopForeground(boolean removeNotification)

Synonym for stopForeground(int).

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 attachBaseContext(Context newBase)

Set the base context for this ContextWrapper.

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

Print the Service's state into the given stream.

Inherited methods

Constants

START_CONTINUATION_MASK

Added in API level 5
public static final int START_CONTINUATION_MASK

Bits returned by onStartCommand(Intent, int, int) describing how to continue the service if it is killed. May be START_STICKY, START_NOT_STICKY, START_REDELIVER_INTENT, or START_STICKY_COMPATIBILITY.

Constant Value: 15 (0x0000000f)

START_FLAG_REDELIVERY

Added in API level 5
public static final int START_FLAG_REDELIVERY

This flag is set in onStartCommand(Intent, int, int) if the Intent is a re-delivery of a previously delivered intent, because the service had previously returned START_REDELIVER_INTENT but had been killed before calling stopSelf(int) for that Intent.

Constant Value: 1 (0x00000001)

START_FLAG_RETRY

Added in API level 5
public static final int START_FLAG_RETRY

This flag is set in onStartCommand(Intent, int, int) if the Intent is a retry because the original attempt never got to or returned from onStartCommand(android.content.Intent, int, int).

Constant Value: 2 (0x00000002)

START_NOT_STICKY

Added in API level 5
public static final int START_NOT_STICKY

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), and there are no new start intents to deliver to it, then take the service out of the started state and don't recreate until a future explicit call to Context.startService(Intent). The service will not receive a onStartCommand(android.content.Intent, int, int) call with a null Intent because it will not be restarted if there are no pending Intents to deliver.

This mode makes sense for things that want to do some work as a result of being started, but can be stopped when under memory pressure and will explicit start themselves again later to do more work. An example of such a service would be one that polls for data from a server: it could schedule an alarm to poll every N minutes by having the alarm start its service. When its onStartCommand(Intent, int, int) is called from the alarm, it schedules a new alarm for N minutes later, and spawns a thread to do its networking. If its process is killed while doing that check, the service will not be restarted until the alarm goes off.

Constant Value: 2 (0x00000002)

START_REDELIVER_INTENT

Added in API level 5
public static final int START_REDELIVER_INTENT

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then it will be scheduled for a restart and the last delivered Intent re-delivered to it again via onStartCommand(Intent, int, int). This Intent will remain scheduled for redelivery until the service calls stopSelf(int) with the start ID provided to onStartCommand(Intent, int, int). The service will not receive a onStartCommand(android.content.Intent, int, int) call with a null Intent because it will only be restarted if it is not finished processing all Intents sent to it (and any such pending events will be delivered at the point of restart).

Constant Value: 3 (0x00000003)

START_STICKY

Added in API level 5
public static final int START_STICKY

Constant to return from onStartCommand(Intent, int, int): if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then leave it in the started state but don't retain this delivered intent. Later the system will try to re-create the service. Because it is in the started state, it will guarantee to call onStartCommand(Intent, int, int) after creating the new service instance; if there are not any pending start commands to be delivered to the service, it will be called with a null intent object, so you must take care to check for this.

This mode makes sense for things that will be explicitly started and stopped to run for arbitrary periods of time, such as a service performing background music playback.

Since Android version Build.VERSION_CODES#S, apps targeting Build.VERSION_CODES#S or above are disallowed to start a foreground service from the background, but the restriction doesn't impact restarts of a sticky foreground service. However, when apps start a sticky foreground service from the background, the same restriction still applies.

Constant Value: 1 (0x00000001)

START_STICKY_COMPATIBILITY

Added in API level 5
public static final int START_STICKY_COMPATIBILITY

Constant to return from onStartCommand(Intent, int, int): compatibility version of START_STICKY that does not guarantee that onStartCommand(Intent, int, int) will be called again after being killed.

Constant Value: 0 (0x00000000)

STOP_FOREGROUND_DETACH

Added in API level 24
public static final int STOP_FOREGROUND_DETACH

Flag for stopForeground(int): if set, the notification previously provided to startForeground(int, Notification) will be detached from the service. Only makes sense when STOP_FOREGROUND_REMOVE is not set -- in this case, the notification will remain shown, but be completely detached from the service and so no longer changed except through direct calls to the notification manager.

Constant Value: 2 (0x00000002)

STOP_FOREGROUND_REMOVE

Added in API level 24
public static final int STOP_FOREGROUND_REMOVE

Flag for stopForeground(int): if set, the notification previously provided to startForeground(int, Notification) will be removed. Otherwise it will remain until a later call (to startForeground(int, android.app.Notification) or stopForeground(int) removes it, or the service is destroyed.

Constant Value: 1 (0x00000001)

Public constructors

Service

Added in API level 1
public Service ()

Public methods

getApplication

Added in API level 1
public final Application getApplication ()

Return the application that owns this service.

Returns Application

getForegroundServiceType

Added in API level 29
public final int getForegroundServiceType ()

If the service has become a foreground service by calling startForeground(int, android.app.Notification) or startForeground(int, android.app.Notification, int), getForegroundServiceType() returns the current foreground service type.

If there is no foregroundServiceType specified in manifest, ServiceInfo#FOREGROUND_SERVICE_TYPE_NONE is returned.

If the service is not a foreground service, ServiceInfo#FOREGROUND_SERVICE_TYPE_NONE is returned.

Returns int current foreground service type flags. Value is either 0 or a combination of ServiceInfo.FOREGROUND_SERVICE_TYPE_MANIFEST, ServiceInfo.FOREGROUND_SERVICE_TYPE_NONE, ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PLAYBACK, ServiceInfo.FOREGROUND_SERVICE_TYPE_PHONE_CALL, ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION, ServiceInfo.FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION, ServiceInfo.FOREGROUND_SERVICE_TYPE_CAMERA, and ServiceInfo.FOREGROUND_SERVICE_TYPE_MICROPHONE

onBind

Added in API level 1
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 the main thread can be found in Processes and Threads.

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

onConfigurationChanged

Added in API level 1
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.

For more information, read Handling Runtime Changes.

Parameters newConfig Configuration: The new device configuration. This value cannot be null.

onCreate

Added in API level 1
public void onCreate ()

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

onDestroy

Added in API level 1
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 any 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.

onLowMemory

Added in API level 1
public void onLowMemory ()

This is called when the overall system is running low on memory, and actively running processes should trim their memory usage. While the exact point at which this will be called is not defined, generally it will happen when 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.

You should implement this method to release any caches or other unnecessary resources you may be holding on to. The system will perform a garbage collection for you after returning from this method.

Preferably, you should implement ComponentCallbacks2#onTrimMemory from ComponentCallbacks2 to incrementally unload your resources based on various levels of memory demands. That API is available for API level 14 and higher, so you should only use this onLowMemory() method as a fallback for older versions, which can be treated the same as ComponentCallbacks2#onTrimMemory with the ComponentCallbacks2.TRIM_MEMORY_COMPLETE level.

onRebind

Added in API level 1
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 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.

onStart

Added in API level 1
Deprecated in API level 15
public void onStart (Intent intent, int startId)

This method was deprecated in API level 15.
Implement onStartCommand(android.content.Intent, int, int) instead.

Parameters intent Intent

startId int

onStartCommand

Added in API level 5
public int onStartCommand (Intent intent, int flags, int startId)

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

For backwards compatibility, the default implementation calls onStart(Intent, int) and returns either START_STICKY or START_STICKY_COMPATIBILITY.

Note that the system calls this on your service's main thread. A service's main thread is the same thread where UI operations take place for Activities running in the same process. You should always avoid stalling the main thread's event loop. When doing long-running operations, network calls, or heavy disk I/O, you should kick off a new thread, or use AsyncTask.

Parameters intent Intent: The Intent supplied to Context.startService(Intent), as given. This may be null if the service is being restarted after its process has gone away, and it had previously returned anything except START_STICKY_COMPATIBILITY.

flags int: Additional data about this start request. Value is either 0 or a combination of START_FLAG_REDELIVERY, and START_FLAG_RETRY

startId int: A unique integer representing this specific request to start. Use with stopSelfResult(int).

Returns int The return value indicates what semantics the system should use for the service's current started state. It may be one of the constants associated with the START_CONTINUATION_MASK bits. Value is START_STICKY_COMPATIBILITY, START_STICKY, START_NOT_STICKY, or START_REDELIVER_INTENT

See also:

  • stopSelfResult(int)

onTaskRemoved

Added in API level 14
public void onTaskRemoved (Intent rootIntent)

This is called if the service is currently running and the user has removed a task that comes from the service's application. If you have set ServiceInfo.FLAG_STOP_WITH_TASK then you will not receive this callback; instead, the service will simply be stopped.

Parameters rootIntent Intent: The original root Intent that was used to launch the task that is being removed.

onTrimMemory

Added in API level 14
public void onTrimMemory (int level)

Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process. This will happen for example when it goes in the background and there is not enough memory to keep as many background processes running as desired. You should never compare to exact values of the level, since new intermediate values may be added -- you will typically want to compare if the value is greater or equal to a level you are interested in.

To retrieve the processes current trim level at any point, you can use ActivityManager.getMyMemoryState(RunningAppProcessInfo).

Parameters level int: The context of the trim, giving a hint of the amount of trimming the application may like to perform. Value is ComponentCallbacks2.TRIM_MEMORY_COMPLETE, ComponentCallbacks2.TRIM_MEMORY_MODERATE, ComponentCallbacks2.TRIM_MEMORY_BACKGROUND, ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN, ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL, ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW, or ComponentCallbacks2.TRIM_MEMORY_RUNNING_MODERATE

onUnbind

Added in API level 1
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 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 boolean Return true if you would like to have the service's onRebind(Intent) method later called when new clients bind to it.

startForeground

Added in API level 5
public final void startForeground (int id, Notification notification)

If your service is started (running through Context#startService(Intent)), then also make this service run in the foreground, supplying the ongoing notification to be shown to the user while in this state. By default started services are background, meaning that their process won't be given foreground CPU scheduling (unless something else in that process is foreground) and, 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 use startForeground(int, Notification) 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.

Note that calling this method does not put the service in the started state itself, even though the name sounds like it. You must always call ContextWrapper.startService(android.content.Intent) first to tell the system it should keep the service running, and then use this method to tell it to keep it running harder.

Apps targeting API Build.VERSION_CODES.P or later must request the permission Manifest.permission.FOREGROUND_SERVICE in order to use this API.

Apps built with SDK version Build.VERSION_CODES.Q or later can specify the foreground service types using attribute R.attr.foregroundServiceType in service element of manifest file. The value of attribute R.attr.foregroundServiceType can be multiple flags ORed together.

Note: Beginning with SDK Version Build.VERSION_CODES.S, apps targeting SDK Version Build.VERSION_CODES.S or higher are not allowed to start foreground services from the background. See Behavior changes: Apps targeting Android 12 for more details.

Parameters id int: The identifier for this notification as per NotificationManager.notify(int, Notification); must not be 0.

notification Notification: The Notification to be displayed.

Throws ForegroundServiceStartNotAllowedException If the app targeting API is Build.VERSION_CODES.S or later, and the service is restricted from becoming foreground service due to background restriction.

See also:

  • stopForeground(boolean)

startForeground

Added in API level 29
public final void startForeground (int id, Notification notification, int foregroundServiceType)

An overloaded version of startForeground(int, android.app.Notification) with additional foregroundServiceType parameter.

Apps built with SDK version Build.VERSION_CODES.Q or later can specify the foreground service types using attribute R.attr.foregroundServiceType in service element of manifest file. The value of attribute R.attr.foregroundServiceType can be multiple flags ORed together.

The foregroundServiceType parameter must be a subset flags of what is specified in manifest attribute R.attr.foregroundServiceType, if not, an IllegalArgumentException is thrown. Specify foregroundServiceType parameter as ServiceInfo.FOREGROUND_SERVICE_TYPE_MANIFEST to use all flags that is specified in manifest attribute foregroundServiceType.

Note: Beginning with SDK Version Build.VERSION_CODES.S, apps targeting SDK Version Build.VERSION_CODES.S or higher are not allowed to start foreground services from the background. See Behavior changes: Apps targeting Android 12 for more details.

Parameters id int: The identifier for this notification as per NotificationManager.notify(int, Notification); must not be 0.

notification Notification: The Notification to be displayed. This value cannot be null.

foregroundServiceType int: must be a subset flags of manifest attribute R.attr.foregroundServiceType flags. Value is either 0 or a combination of ServiceInfo.FOREGROUND_SERVICE_TYPE_MANIFEST, ServiceInfo.FOREGROUND_SERVICE_TYPE_NONE, ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PLAYBACK, ServiceInfo.FOREGROUND_SERVICE_TYPE_PHONE_CALL, ServiceInfo.FOREGROUND_SERVICE_TYPE_LOCATION, ServiceInfo.FOREGROUND_SERVICE_TYPE_CONNECTED_DEVICE, ServiceInfo.FOREGROUND_SERVICE_TYPE_MEDIA_PROJECTION, ServiceInfo.FOREGROUND_SERVICE_TYPE_CAMERA, and ServiceInfo.FOREGROUND_SERVICE_TYPE_MICROPHONE

Throws IllegalArgumentException if param foregroundServiceType is not subset of manifest attribute R.attr.foregroundServiceType. ForegroundServiceStartNotAllowedException If the app targeting API is Build.VERSION_CODES.S or later, and the service is restricted from becoming foreground service due to background restriction.

See also:

  • ServiceInfo.FOREGROUND_SERVICE_TYPE_MANIFEST

stopForeground

Added in API level 24
public final void stopForeground (int flags)

Remove this service from foreground state, allowing it to be killed if more memory is needed. This does not stop the service from running (for that you use stopSelf() or related methods), just takes it out of the foreground state.

Parameters flags int: additional behavior options. Value is either 0 or a combination of STOP_FOREGROUND_REMOVE, and STOP_FOREGROUND_DETACH

See also:

  • startForeground(int, Notification)

stopForeground

Added in API level 5
public final void stopForeground (boolean removeNotification)

Synonym for stopForeground(int).

Parameters removeNotification boolean: If true, the STOP_FOREGROUND_REMOVE flag will be supplied.

See also:

  • stopForeground(int)
  • startForeground(int, Notification)

stopSelf

Added in API level 1
public final void stopSelf ()

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

See also:

  • stopSelfResult(int)

stopSelf

Added in API level 1
public final void stopSelf (int startId)

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

Parameters startId int

See also:

  • stopSelfResult(int)

stopSelfResult

Added in API level 1
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 Context.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).

Be careful about ordering of your calls to this function.. If you call this function with the most-recently received ID before you have called it for previously received IDs, the service will be immediately stopped anyway. If you may end up processing IDs out of order (such as by dispatching them on separate threads), then you are responsible for stopping them in the same order you received them.

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

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

See also:

  • stopSelf()

Protected methods

attachBaseContext

Added in API level 1
protected void attachBaseContext (Context newBase)

Set the base context for this ContextWrapper. All calls will then be delegated to the base context. Throws IllegalStateException if a base context has already been set.

Parameters newBase Context: The new base context for this wrapper.

dump

Added in API level 1
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 <yourservicename>" (note that for this command to work, the service must be running, and you must specify a fully-qualified service name). This is distinct from "dumpsys <servicename>", which only works for named system services and which invokes the IBinder#dump method on the IBinder interface registered with ServiceManager.

Parameters fd FileDescriptor: The raw file descriptor that the dump is being sent to.

writer PrintWriter: The PrintWriter to which you should dump your state. This will be closed for you after you return.

args String: additional arguments to the dump request.

Content and code samples on this page are subject to the licenses described in the Content License. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2021-09-08 UTC.

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