| Package | Description | 
|---|---|
| io.reactivex.rxjava3.annotations | Annotations for indicating operator behavior, API stability
 ( @Experimentaland@Beta) and
 nullability indicators (NullableandNonNull). | 
| io.reactivex.rxjava3.core | Base reactive classes:  Flowable,Observable,Single,MaybeandCompletable; base reactive consumers;
 other common base interfaces. | 
| io.reactivex.rxjava3.disposables | Default implementations for  Disposable-based resource management
 (Disposablecontainer types) and utility classes to constructDisposablesfrom callbacks and other types. | 
| io.reactivex.rxjava3.exceptions | Exception handling utilities ( Exceptions),
 composite exception container (CompositeException) and
 various lifecycle-related (UndeliverableException)
 and behavior-violation exception types (OnErrorNotImplementedException,MissingBackpressureException). | 
| io.reactivex.rxjava3.flowables | Classes supporting the Flowable base reactive class:
  ConnectableFlowableandGroupedFlowable. | 
| io.reactivex.rxjava3.functions | Functional interfaces of functions and actions of arity 0 to 9 and related
 utility classes. | 
| io.reactivex.rxjava3.observables | Classes supporting the Observable base reactive class:
  ConnectableObservableandGroupedObservable. | 
| io.reactivex.rxjava3.observers | Default wrappers and implementations for observer-based consumer classes and interfaces,
 including disposable and resource-tracking variants and
 the  TestObserverthat allows unit testingObservable-,Single-,Maybe- andCompletable-based flows. | 
| io.reactivex.rxjava3.parallel | Contains the base type  ParallelFlowable,
 a sub-DSL for working withFlowablesequences in parallel. | 
| io.reactivex.rxjava3.plugins | Contains the central plugin handler  RxJavaPluginsclass to hook into the lifecycle of the base reactive types and schedulers. | 
| io.reactivex.rxjava3.processors | Classes representing so-called hot backpressure-aware sources, aka processors,
 that implement the  FlowableProcessorclass,
 the Reactive StreamsProcessorinterface
 to allow forms of multicasting events to one or more subscribers as well as consuming another
 Reactive StreamsPublisher. | 
| io.reactivex.rxjava3.schedulers | Contains notably the factory class of  Schedulersproviding methods for
 retrieving the standard scheduler instances, theTestSchedulerfor testing flows
 with scheduling in a controlled manner and the classTimedthat can hold
 a value and a timestamp associated with it. | 
| io.reactivex.rxjava3.subjects | Classes representing so-called hot sources, aka subjects, that implement a base reactive class and
 the respective consumer type at once to allow forms of multicasting events to multiple
 consumers as well as consuming another base reactive type of their kind. | 
| io.reactivex.rxjava3.subscribers | Default wrappers and implementations for  Subscriber-based consumer classes and interfaces,
 including disposable (DisposableSubscriber) and resource-tracking
 (ResourceSubscriber)
 variants and theTestSubscriberthat allows unit testingFlowable-based flows. |