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LiveDataReactiveStreams

class LiveDataReactiveStreams
kotlin.Any
   ↳ androidx.lifecycle.LiveDataReactiveStreams

Adapts LiveData input and output to the ReactiveStreams spec.

Summary

Public methods
static Publisher<T>
toPublisher(@NonNull lifecycle: LifecycleOwner, @NonNull liveData: LiveData<T>)

Adapts the given LiveData stream to a ReactiveStreams Publisher.

static LiveData<T>
fromPublisher(@NonNull publisher: Publisher<T>)

Creates an observable LiveData stream from a ReactiveStreams Publisher}.

Public methods

toPublisher

@NonNull static fun <T : Any!> toPublisher(@NonNull lifecycle: LifecycleOwner, @NonNull liveData: LiveData<T>): Publisher<T>

Adapts the given LiveData stream to a ReactiveStreams Publisher.

By using a good publisher implementation such as RxJava 2.x Flowables, most consumers will be able to let the library deal with backpressure using operators and not need to worry about ever manually calling Subscription#request.

On subscription to the publisher, the observer will attach to the given LiveData. Once Subscription#request is called on the subscription object, an observer will be connected to the data stream. Calling request(Long.MAX_VALUE) is equivalent to creating an unbounded stream with no backpressure. If request with a finite count reaches 0, the observer will buffer the latest item and emit it to the subscriber when data is again requested. Any other items emitted during the time there was no backpressure requested will be dropped.

fromPublisher

@NonNull static fun <T : Any!> fromPublisher(@NonNull publisher: Publisher<T>): LiveData<T>

Creates an observable LiveData stream from a ReactiveStreams Publisher}.

When the LiveData becomes active, it subscribes to the emissions from the Publisher.

When the LiveData becomes inactive, the subscription is cleared. LiveData holds the last value emitted by the Publisher when the LiveData was active.

Therefore, in the case of a hot RxJava Observable, when a new LiveData Observer is added, it will automatically notify with the last value held in LiveData, which might not be the last value emitted by the Publisher.

Note that LiveData does NOT handle errors and it expects that errors are treated as states in the data that's held. In case of an error being emitted by the publisher, an error will be propagated to the main thread and the app will crash.

Parameters
<T> Publisher<T>: The type of data hold by this instance.