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IntentService

public abstract class IntentService
extends Service

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


IntentService is a base class for Services that handle asynchronous requests (expressed as Intents) on demand. Clients send requests through Context.startService(Intent) calls; the service is started as needed, handles each Intent in turn using a worker thread, and stops itself when it runs out of work.

This "work queue processor" pattern is commonly used to offload tasks from an application's main thread. The IntentService class exists to simplify this pattern and take care of the mechanics. To use it, extend IntentService and implement onHandleIntent(Intent). IntentService will receive the Intents, launch a worker thread, and stop the service as appropriate.

All requests are handled on a single worker thread -- they may take as long as necessary (and will not block the application's main loop), but only one request will be processed at a time.

Note: IntentService is subject to all the background execution limits imposed with Android 8.0 (API level 26). In most cases, you are better off using JobIntentService, which uses jobs instead of services when running on Android 8.0 or higher.

Developer Guides

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

Summary

Inherited constants

Public constructors

IntentService(String name)

Creates an IntentService.

Public methods

IBinder onBind(Intent intent)

Unless you provide binding for your service, you don't need to implement this method, because the default implementation returns null.

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 onStart(Intent intent, int startId)

This method is deprecated. Implement onStartCommand(Intent, int, int) instead.

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

You should not override this method for your IntentService.

void setIntentRedelivery(boolean enabled)

Sets intent redelivery preferences.

Protected methods

abstract void onHandleIntent(Intent intent)

This method is invoked on the worker thread with a request to process.

Inherited methods

Public constructors

IntentService

added in API level 3
public IntentService (String name)

Creates an IntentService. Invoked by your subclass's constructor.

Parameters
name String: Used to name the worker thread, important only for debugging.

Public methods

onBind

added in API level 3
public IBinder onBind (Intent intent)

Unless you provide binding for your service, you don't need to implement this method, because the default implementation returns null.

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.

This value may be null.

onCreate

added in API level 3
public void onCreate ()

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

onDestroy

added in API level 3
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.

onStart

added in API level 3
public void onStart (Intent intent, 
                int startId)

This method is deprecated.
Implement onStartCommand(Intent, int, int) instead.

Parameters
intent Intent

This value may be null.

startId int

onStartCommand

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

You should not override this method for your IntentService. Instead, override onHandleIntent(Intent), which the system calls when the IntentService receives a start request.

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 Service.START_STICKY_COMPATIBILITY.

flags int: Additional data about this start request.

startId int: A unique integer representing this specific request to start. Use with Service.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.

setIntentRedelivery

added in API level 5
public void setIntentRedelivery (boolean enabled)

Sets intent redelivery preferences. Usually called from the constructor with your preferred semantics.

If enabled is true, onStartCommand(Intent, int, int) will return Service.START_REDELIVER_INTENT, so if this process dies before onHandleIntent(Intent) returns, the process will be restarted and the intent redelivered. If multiple Intents have been sent, only the most recent one is guaranteed to be redelivered.

If enabled is false (the default), onStartCommand(Intent, int, int) will return Service.START_NOT_STICKY, and if the process dies, the Intent dies along with it.

Parameters
enabled boolean

Protected methods

onHandleIntent

added in API level 3
protected abstract void onHandleIntent (Intent intent)

This method is invoked on the worker thread with a request to process. Only one Intent is processed at a time, but the processing happens on a worker thread that runs independently from other application logic. So, if this code takes a long time, it will hold up other requests to the same IntentService, but it will not hold up anything else. When all requests have been handled, the IntentService stops itself, so you should not call Service.stopSelf().

This method may take several seconds to complete, so it should only be called from a worker thread.

Parameters
intent Intent: The value passed to Context.startService(Intent). This may be null if the service is being restarted after its process has gone away; see Service.onStartCommand(Intent, int, int) for details.