WorkManager

public abstract class WorkManager
extends Object

java.lang.Object
   ↳ androidx.work.WorkManager


WorkManager is a library used to enqueue deferrable work that is guaranteed to execute sometime after its Constraints are met. WorkManager allows observation of work status and the ability to create complex chains of work.

WorkManager uses an underlying job dispatching service when available based on the following criteria:

  • Uses JobScheduler for API 23+
  • Uses a custom AlarmManager + BroadcastReceiver implementation for API 14-22

All work must be done in a ListenableWorker class. A simple implementation, Worker, is recommended as the starting point for most developers. With the optional dependencies, you can also use CoroutineWorker or RxWorker. All background work is given a maximum of ten minutes to finish its execution. After this time has expired, the worker will be signalled to stop.

There are two types of work supported by WorkManager: OneTimeWorkRequest and PeriodicWorkRequest. You can enqueue requests using WorkManager as follows:

 WorkManager workManager = WorkManager.getInstance(Context);
 workManager.enqueue(new OneTimeWorkRequest.Builder(FooWorker.class).build());
 
A WorkRequest has an associated id that can be used for lookups and observation as follows:
 WorkRequest request = new OneTimeWorkRequest.Builder(FooWorker.class).build();
 workManager.enqueue(request);
 LiveData status = workManager.getWorkInfoByIdLiveData(request.getId());
 status.observe(...);
 
You can also use the id for cancellation:
 WorkRequest request = new OneTimeWorkRequest.Builder(FooWorker.class).build();
 workManager.enqueue(request);
 workManager.cancelWorkById(request.getId());
 
You can chain work as follows:
 WorkRequest request1 = new OneTimeWorkRequest.Builder(FooWorker.class).build();
 WorkRequest request2 = new OneTimeWorkRequest.Builder(BarWorker.class).build();
 WorkRequest request3 = new OneTimeWorkRequest.Builder(BazWorker.class).build();
 workManager.beginWith(request1, request2).then(request3).enqueue();
 
Each call to beginWith(OneTimeWorkRequest) or beginWith(List) returns a WorkContinuation upon which you can call WorkContinuation.then(OneTimeWorkRequest) or WorkContinuation.then(List) to chain further work. This allows for creation of complex chains of work. For example, to create a chain like this:
            A
            |
      +----------+
      |          |
      B          C
      |
   +----+
   |    |
   D    E             
you would enqueue them as follows:
 WorkContinuation continuation = workManager.beginWith(A);
 continuation.then(B).then(D, E).enqueue();  // A is implicitly enqueued here
 continuation.then(C).enqueue();
 
Work is eligible for execution when all of its prerequisites are complete. If any of its prerequisites fail or are cancelled, the work will never run.

WorkRequests can accept Constraints, inputs (see Data), and backoff criteria. WorkRequests can be tagged with human-readable Strings (see WorkRequest.Builder.addTag(String)), and chains of work can be given a uniquely-identifiable name (see beginUniqueWork(String, ExistingWorkPolicy, OneTimeWorkRequest)).

Initializing WorkManager

By default, WorkManager auto-initializes itself using a built-in ContentProvider. ContentProviders are created and run before the Application object, so this allows the WorkManager singleton to be setup before your code can run in most cases. This is suitable for most developers. However, you can provide a custom Configuration by using Configuration.Provider or initialize(android.content.Context, androidx.work.Configuration).

Renaming and Removing ListenableWorker Classes

Exercise caution in renaming classes derived from ListenableWorkers. WorkManager stores the class name in its internal database when the WorkRequest is enqueued so it can later create an instance of that worker when constraints are met. Unless otherwise specified in the WorkManager Configuration, this is done in the default WorkerFactory which tries to reflectively create the ListenableWorker object. Therefore, renaming or removing these classes is dangerous - if there is pending work with the given class, it will fail permanently if the class cannot be found. If you are using a custom WorkerFactory, make sure you properly handle cases where the class is not found so that your code does not crash.

In case it is desirable to rename a class, implement a custom WorkerFactory that instantiates the right ListenableWorker for the old class name.

Summary

Public methods

abstract WorkContinuation beginUniqueWork(String uniqueWorkName, ExistingWorkPolicy existingWorkPolicy, List<OneTimeWorkRequest> work)

This method allows you to begin unique chains of work for situations where you only want one chain with a given name to be active at a time.

final WorkContinuation beginUniqueWork(String uniqueWorkName, ExistingWorkPolicy existingWorkPolicy, OneTimeWorkRequest work)

This method allows you to begin unique chains of work for situations where you only want one chain with a given name to be active at a time.

final WorkContinuation beginWith(OneTimeWorkRequest work)

Begins a chain with one or more OneTimeWorkRequests, which can be enqueued together in the future using WorkContinuation.enqueue().

abstract WorkContinuation beginWith(List<OneTimeWorkRequest> work)

Begins a chain with one or more OneTimeWorkRequests, which can be enqueued together in the future using WorkContinuation.enqueue().

abstract Operation cancelAllWork()

Cancels all unfinished work.

abstract Operation cancelAllWorkByTag(String tag)

Cancels all unfinished work with the given tag.

abstract Operation cancelUniqueWork(String uniqueWorkName)

Cancels all unfinished work in the work chain with the given name.

abstract Operation cancelWorkById(UUID id)

Cancels work with the given id if it isn't finished.

abstract PendingIntent createCancelPendingIntent(UUID id)

Creates a PendingIntent which can be used to cancel a WorkRequest with the given id.

final Operation enqueue(WorkRequest workRequest)

Enqueues one item for background processing.

abstract Operation enqueue(List<? extends WorkRequest> requests)

Enqueues one or more items for background processing.

abstract Operation enqueueUniquePeriodicWork(String uniqueWorkName, ExistingPeriodicWorkPolicy existingPeriodicWorkPolicy, PeriodicWorkRequest periodicWork)

This method allows you to enqueue a uniquely-named PeriodicWorkRequest, where only one PeriodicWorkRequest of a particular name can be active at a time.

abstract Operation enqueueUniqueWork(String uniqueWorkName, ExistingWorkPolicy existingWorkPolicy, List<OneTimeWorkRequest> work)

This method allows you to enqueue work requests to a uniquely-named