Package io.reactivex.rxjava3.observers

Default wrappers and implementations for observer-based consumer classes and interfaces, including disposable and resource-tracking variants and the TestObserver that allows unit testing Observable-, Single-, Maybe- and Completable-based flows.

Available observer variants

The available observer types.

Reactive type	Base interface	Simple	Disposable	Resource
Observable	Observer	DefaultObserver	DisposableObserver	DisposableObserver
Maybe	MaybeObserver	N/A	DisposableMaybeObserver	DisposableMaybeObserver
Single	SingleObserver	N/A	DisposableSingleObserver	DisposableSingleObserver
Completable	CompletableObserver	N/A	DisposableCompletableObserver	DisposableCompletableObserver

Interface Summary

Interface	Description
LambdaConsumerIntrospection	An interface that indicates that the implementing type is composed of individual components and exposes information about their behavior.

Class Summary

Class	Description
BaseTestConsumer<T,U extends BaseTestConsumer<T,U>>	Base class with shared infrastructure to support TestSubscriber and TestObserver.
DefaultObserver<T>	Abstract base implementation of an Observer with support for cancelling a subscription via DefaultObserver.cancel() (synchronously) and calls DefaultObserver.onStart() when the subscription happens.
DisposableCompletableObserver	An abstract CompletableObserver that allows asynchronous cancellation by implementing Disposable.
DisposableMaybeObserver<T>	An abstract MaybeObserver that allows asynchronous cancellation by implementing Disposable.
DisposableObserver<T>	An abstract Observer that allows asynchronous cancellation by implementing Disposable.
DisposableSingleObserver<T>	An abstract SingleObserver that allows asynchronous cancellation by implementing Disposable.
ResourceCompletableObserver	An abstract CompletableObserver that allows asynchronous cancellation of its subscription and associated resources.
ResourceMaybeObserver<T>	An abstract MaybeObserver that allows asynchronous cancellation of its subscription and associated resources.
ResourceObserver<T>	An abstract Observer that allows asynchronous cancellation of its subscription and associated resources.
ResourceSingleObserver<T>	An abstract SingleObserver that allows asynchronous cancellation of its subscription and the associated resources.
SafeObserver<T>	Wraps another Observer and ensures all onXXX methods conform the protocol (except the requirement for serialized access).
SerializedObserver<T>	Serializes access to the Observer.onNext(Object), Observer.onError(Throwable) and Observer.onComplete() methods of another Observer.
TestObserver<T>	An Observer, MaybeObserver, SingleObserver and CompletableObserver composite that can record events from Observables, Maybes, Singles and Completables and allows making assertions about them.

Enum Summary

Enum	Description
TestObserver.EmptyObserver	An observer that ignores all events and does not report errors.