WorkContinuation

Added in 1.0.0

Kotlin |Java

public abstract class WorkContinuation

A class that allows you to chain together OneTimeWorkRequests. WorkContinuations allow the user to create arbitrary acyclic graphs of work dependencies. You can add dependent work to a WorkContinuation by invoking then or its variants. This returns a new WorkContinuation.

To construct more complex graphs, combine or its variants can be used to return a WorkContinuation with the input WorkContinuations as prerequisites. To create a graph like this:

    A       C
    |       |
    B       D
    |       |
    +-------+
        |
E

you would write the following:

 WorkContinuation left = workManager.beginWith(A).then(B);
 WorkContinuation right = workManager.beginWith(C).then(D);
 WorkContinuation final = WorkContinuation.combine(Arrays.asList(left, right)).then(E);
 final.enqueue();

Not that enqueuing a WorkContinuation enqueues all previously-unenqueued prerequisites. You must call enqueue to inform WorkManager to actually enqueue the work graph. As usual, enqueues are asynchronous - you can observe or block on the returned Operation if you need to be informed about its completion.

Because of the fluent nature of this class, its existence should be invisible in most cases.

Summary

Public constructors
`WorkContinuation()`

Public methods
`static @NonNull WorkContinuation`	`combine(@NonNull List<WorkContinuation> continuations)` Combines multiple `WorkContinuation`s as prerequisites for a new WorkContinuation to allow for complex chaining.
`abstract @NonNull Operation`	`enqueue()` Enqueues the instance of `WorkContinuation` on the background thread.
`abstract @NonNull ListenableFuture<List<WorkInfo>>`	`getWorkInfos()` Returns a `ListenableFuture` of a `List` of `WorkInfo`s that provides information about the status of each `OneTimeWorkRequest` in this `WorkContinuation`, as well as their prerequisites.
`abstract @NonNull LiveData<List<WorkInfo>>`	`getWorkInfosLiveData()` Returns a `LiveData` list of `WorkInfo`s that provide information about the status of each `OneTimeWorkRequest` in this `WorkContinuation`, as well as their prerequisites.
`abstract @NonNull WorkContinuation`	`then(@NonNull List<OneTimeWorkRequest> work)` Adds new `OneTimeWorkRequest` items that depend on the successful completion of all previously added `OneTimeWorkRequest`s.
`final @NonNull WorkContinuation`	`then(@NonNull OneTimeWorkRequest work)` Adds new `OneTimeWorkRequest` items that depend on the successful completion of all previously added `OneTimeWorkRequest`s.

Public constructors

WorkContinuation

Added in 1.0.0

public WorkContinuation()

Public methods

combine

Added in 1.0.0

public static @NonNull WorkContinuation combine(@NonNull List<WorkContinuation> continuations)

Combines multiple WorkContinuations as prerequisites for a new WorkContinuation to allow for complex chaining. For example, to create a graph like this:

    A       C
    |       |
    B       D
    |       |
    +-------+
        |
E

you would write the following:

 WorkContinuation left = workManager.beginWith(A).then(B);
 WorkContinuation right = workManager.beginWith(C).then(D);
 WorkContinuation final = WorkContinuation.combine(Arrays.asList(left, right)).then(E);
 final.enqueue();

Parameters
`@NonNull List<WorkContinuation> continuations`	One or more `WorkContinuation`s that are prerequisites for the return value

Returns
`@NonNull WorkContinuation`	A `WorkContinuation` that allows further chaining

enqueue

Added in 1.0.0

public abstract @NonNull Operation enqueue()

Enqueues the instance of WorkContinuation on the background thread.

Returns
`@NonNull Operation`	An `Operation` that can be used to determine when the enqueue has completed

getWorkInfos

Added in 1.0.0

public abstract @NonNull ListenableFuture<List<WorkInfo>> getWorkInfos()

Returns a ListenableFuture of a List of WorkInfos that provides information about the status of each OneTimeWorkRequest in this WorkContinuation, as well as their prerequisites.

Returns
`@NonNull ListenableFuture<List<WorkInfo>>`	A `ListenableFuture` of a `List` of `WorkInfo`s

getWorkInfosLiveData

Added in 1.0.0

public abstract @NonNull LiveData<List<WorkInfo>> getWorkInfosLiveData()

Returns a LiveData list of WorkInfos that provide information about the status of each OneTimeWorkRequest in this WorkContinuation, as well as their prerequisites. If the state or outputs of any of the work changes, any attached Observers will trigger.

Returns
`@NonNull LiveData<List<WorkInfo>>`	A `LiveData` containing a list of `WorkInfo`s; you must use `observe` to receive updates

then

Added in 1.0.0

public abstract @NonNull WorkContinuation then(@NonNull List<OneTimeWorkRequest> work)

Adds new OneTimeWorkRequest items that depend on the successful completion of all previously added OneTimeWorkRequests.

Parameters
`@NonNull List<OneTimeWorkRequest> work`	One or more `OneTimeWorkRequest` to add as dependents

Returns
`@NonNull WorkContinuation`	A `WorkContinuation` that allows for further chaining of dependent `OneTimeWorkRequest`s

then

Added in 1.0.0

public final @NonNull WorkContinuation then(@NonNull OneTimeWorkRequest work)

Adds new OneTimeWorkRequest items that depend on the successful completion of all previously added OneTimeWorkRequests.

Parameters
`@NonNull OneTimeWorkRequest work`	One or more `OneTimeWorkRequest`s to add as dependents

Returns
`@NonNull WorkContinuation`	A `WorkContinuation` that allows for further chaining of dependent `OneTimeWorkRequest`s