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Alphabetical List of Observable Operators

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akarnokd edited this page Jun 5, 2019 · 142 revisions
  • aggregate( ) — see reduce( )
  • all( ) — determine whether all items emitted by an Observable meet some criteria
  • amb( ) — given two or more source Observables, emits all of the items from the first of these Observables to emit an item
  • ambWith( ) — instance version of amb( )
  • and( ) — combine the emissions from two or more source Observables into a Pattern (rxjava-joins)
  • apply( ) (scala) — see create( )
  • asObservable( ) (kotlin) — see from( ) (et al.)
  • asyncAction( ) — convert an Action into an Observable that executes the Action and emits its return value (rxjava-async)
  • asyncFunc( ) — convert a function into an Observable that executes the function and emits its return value (rxjava-async)
  • averageDouble( ) — calculates the average of Doubles emitted by an Observable and emits this average (rxjava-math)
  • averageFloat( ) — calculates the average of Floats emitted by an Observable and emits this average (rxjava-math)
  • averageInteger( ) — calculates the average of Integers emitted by an Observable and emits this average (rxjava-math)
  • averageLong( ) — calculates the average of Longs emitted by an Observable and emits this average (rxjava-math)
  • blocking( ) (clojure) — see toBlocking( )
  • buffer( ) — periodically gather items from an Observable into bundles and emit these bundles rather than emitting the items one at a time
  • byLine( ) (StringObservable) — converts an Observable of Strings into an Observable of Lines by treating the source sequence as a stream and splitting it on line-endings
  • cache( ) — remember the sequence of items emitted by the Observable and emit the same sequence to future Subscribers
  • cast( ) — cast all items from the source Observable into a particular type before reemitting them
  • catch( ) (clojure) — see onErrorResumeNext( )
  • chunkify( ) — returns an iterable that periodically returns a list of items emitted by the source Observable since the last list (⁇)
  • collect( ) — collects items emitted by the source Observable into a single mutable data structure and returns an Observable that emits this structure
  • combineLatest( ) — when an item is emitted by either of two Observables, combine the latest item emitted by each Observable via a specified function and emit items based on the results of this function
  • combineLatestWith( ) (scala) — instance version of combineLatest( )
  • concat( ) — concatenate two or more Observables sequentially
  • concatMap( ) — transform the items emitted by an Observable into Observables, then flatten this into a single Observable, without interleaving
  • concatWith( ) — instance version of concat( )
  • connect( ) — instructs a Connectable Observable to begin emitting items
  • cons( ) (clojure) — see concat( )
  • contains( ) — determine whether an Observable emits a particular item or not
  • count( ) — counts the number of items emitted by an Observable and emits this count
  • countLong( ) — counts the number of items emitted by an Observable and emits this count
  • create( ) — create an Observable from scratch by means of a function
  • cycle( ) (clojure) — see repeat( )
  • debounce( ) — only emit an item from the source Observable after a particular timespan has passed without the Observable emitting any other items
  • decode( ) (StringObservable) — convert a stream of multibyte characters into an Observable that emits byte arrays that respect character boundaries
  • defaultIfEmpty( ) — emit items from the source Observable, or emit a default item if the source Observable completes after emitting no items
  • defer( ) — do not create the Observable until a Subscriber subscribes; create a fresh Observable on each subscription
  • deferFuture( ) — convert a Future that returns an Observable into an Observable, but do not attempt to get the Observable that the Future returns until a Subscriber subscribes (rxjava-async)
  • deferCancellableFuture( ) — convert a Future that returns an Observable into an Observable in a way that monitors the subscription status of the Observable to determine whether to halt work on the Future, but do not attempt to get the returned Observable until a Subscriber subscribes (⁇)(rxjava-async)
  • delay( ) — shift the emissions from an Observable forward in time by a specified amount
  • dematerialize( ) — convert a materialized Observable back into its non-materialized form
  • distinct( ) — suppress duplicate items emitted by the source Observable
  • distinctUntilChanged( ) — suppress duplicate consecutive items emitted by the source Observable
  • do( ) (clojure) — see doOnEach( )
  • doOnCompleted( ) — register an action to take when an Observable completes successfully
  • doOnEach( ) — register an action to take whenever an Observable emits an item
  • doOnError( ) — register an action to take when an Observable completes with an error
  • doOnNext( ) — see doOnEach( )
  • doOnRequest( ) — register an action to take when items are requested from an Observable via reactive-pull backpressure (⁇)
  • doOnSubscribe( ) — register an action to take when an observer subscribes to an Observable
  • doOnTerminate( ) — register an action to take when an Observable completes, either successfully or with an error
  • doOnUnsubscribe( ) — register an action to take when an observer unsubscribes from an Observable
  • doWhile( ) — emit the source Observable's sequence, and then repeat the sequence as long as a condition remains true (contrib-computation-expressions)
  • drop( ) (scala/clojure) — see skip( )
  • dropRight( ) (scala) — see skipLast( )
  • dropUntil( ) (scala) — see skipUntil( )
  • dropWhile( ) (scala) — see skipWhile( )
  • drop-while( ) (clojure) — see skipWhile( )
  • elementAt( ) — emit item n emitted by the source Observable
  • elementAtOrDefault( ) — emit item n emitted by the source Observable, or a default item if the source Observable emits fewer than n items
  • empty( ) — create an Observable that emits nothing and then completes
  • encode( ) (StringObservable) — transform an Observable that emits strings into an Observable that emits byte arrays that respect character boundaries of multibyte characters in the original strings
  • error( ) — create an Observable that emits nothing and then signals an error
  • every( ) (clojure) — see all( )
  • exists( ) — determine whether an Observable emits any items or not
  • filter( ) — filter items emitted by an Observable
  • finally( ) (clojure) — see finallyDo( )
  • filterNot( ) (scala) — see filter( )
  • finallyDo( ) — register an action to take when an Observable completes
  • first( ) (Observable) — emit only the first item emitted by an Observable, or the first item that meets some condition
  • first( ) (BlockingObservable) — emit only the first item emitted by an Observable, or the first item that meets some condition
  • firstOrDefault( ) (Observable) — emit only the first item emitted by an Observable, or the first item that meets some condition, or a default value if the source Observable is empty
  • firstOrDefault( ) (BlockingObservable) — emit only the first item emitted by an Observable, or the first item that meets some condition, or a default value if the source Observable is empty
  • firstOrElse( ) (scala) — see firstOrDefault( ) or firstOrDefault( ) (BlockingObservable)
  • flatMap( ) — transform the items emitted by an Observable into Observables, then flatten this into a single Observable
  • flatMapIterable( ) — create Iterables corresponding to each emission from a source Observable and merge the results into a single Observable
  • flatMapIterableWith( ) (scala) — instance version of flatMapIterable( )
  • flatMapWith( ) (scala) — instance version of flatmap( )
  • flatten( ) (scala) — see merge( )
  • flattenDelayError( ) (scala) — see mergeDelayError( )
  • foldLeft( ) (scala) — see reduce( )
  • forall( ) (scala) — see all( )
  • forEach( ) (Observable) — see subscribe( )
  • forEach( ) (BlockingObservable) — invoke a function on each item emitted by the Observable; block until the Observable completes
  • forEachFuture( ) (Async) — pass Subscriber methods to an Observable but also have it behave like a Future that blocks until it completes (rxjava-async)
  • forEachFuture( ) (BlockingObservable)— create a futureTask that will invoke a specified function on each item emitted by an Observable (⁇)
  • forIterable( ) — apply a function to the elements of an Iterable to create Observables which are then concatenated (⁇)
  • from( ) — convert an Iterable, a Future, or an Array into an Observable
  • from( ) (StringObservable) — convert a stream of characters or a Reader into an Observable that emits byte arrays or Strings
  • fromAction( ) — convert an Action into an Observable that invokes the action and emits its result when a Subscriber subscribes (rxjava-async)
  • fromCallable( ) — convert a Callable into an Observable that invokes the callable and emits its result or exception when a Subscriber subscribes (rxjava-async)
  • fromCancellableFuture( ) — convert a Future into an Observable in a way that monitors the subscription status of the Observable to determine whether to halt work on the Future, but do not attempt to get the Future's value until a Subscriber subscribes (⁇)(rxjava-async)
  • fromFunc0( ) — see fromCallable( ) (rxjava-async)
  • fromFuture( ) — convert a Future into an Observable, but do not attempt to get the Future's value until a Subscriber subscribes (⁇)
  • fromRunnable( ) — convert a Runnable into an Observable that invokes the runable and emits its result when a Subscriber subscribes (rxjava-async)
  • generate( ) — create an Observable that emits a sequence of items as generated by a function of your choosing (⁇)
  • generateAbsoluteTime( ) — create an Observable that emits a sequence of items as generated by a function of your choosing, with each item emitted at an item-specific time (⁇)
  • generator( ) (clojure) — see generate( )
  • getIterator( ) — convert the sequence emitted by the Observable into an Iterator
  • groupBy( ) — divide an Observable into a set of Observables that emit groups of items from the original Observable, organized by key
  • group-by( ) (clojure) — see groupBy( )
  • groupByUntil( ) — a variant of the groupBy( ) operator that closes any open GroupedObservable upon a signal from another Observable (⁇)
  • groupJoin( ) — combine the items emitted by two Observables whenever one item from one Observable falls within a window of duration specified by an item emitted by the other Observable
  • head( ) (scala) — see first( ) (BlockingObservable)
  • headOption( ) (scala) — see firstOrDefault( ) or firstOrDefault( ) (BlockingObservable)
  • headOrElse( ) (scala) — see firstOrDefault( ) or firstOrDefault( ) (BlockingObservable)
  • ifThen( ) — only emit the source Observable's sequence if a condition is true, otherwise emit an empty or default sequence (contrib-computation-expressions)
  • ignoreElements( ) — discard the items emitted by the source Observable and only pass through the error or completed notification
  • interval( ) — create an Observable that emits a sequence of integers spaced by a given time interval
  • into( ) (clojure) — see reduce( )
  • isEmpty( ) — determine whether an Observable emits any items or not
  • items( ) (scala) — see just( )
  • join( ) — combine the items emitted by two Observables whenever one item from one Observable falls within a window of duration specified by an item emitted by the other Observable
  • join( ) (StringObservable) — converts an Observable that emits a sequence of strings into an Observable that emits a single string that concatenates them all, separating them by a specified string
  • just( ) — convert an object into an Observable that emits that object
  • last( ) (BlockingObservable) — block until the Observable completes, then return the last item emitted by the Observable
  • last( ) (Observable) — emit only the last item emitted by the source Observable
  • lastOption( ) (scala) — see lastOrDefault( ) or lastOrDefault( ) (BlockingObservable)
  • lastOrDefault( ) (BlockingObservable) — block until the Observable completes, then return the last item emitted by the Observable or a default item if there is no last item
  • lastOrDefault( ) (Observable) — emit only the last item emitted by an Observable, or a default value if the source Observable is empty
  • lastOrElse( ) (scala) — see lastOrDefault( ) or lastOrDefault( ) (BlockingObservable)
  • latest( ) — returns an iterable that blocks until or unless the Observable emits an item that has not been returned by the iterable, then returns the latest such item
  • length( ) (scala) — see count( )
  • limit( ) — see take( )
  • longCount( ) (scala) — see countLong( )
  • map( ) — transform the items emitted by an Observable by applying a function to each of them
  • mapcat( ) (clojure) — see concatMap( )
  • mapMany( ) — see: flatMap( )
  • materialize( ) — convert an Observable into a list of Notifications
  • max( ) — emits the maximum value emitted by a source Observable (rxjava-math)
  • maxBy( ) — emits the item emitted by the source Observable that has the maximum key value (rxjava-math)
  • merge( ) — combine multiple Observables into one
  • mergeDelayError( ) — combine multiple Observables into one, allowing error-free Observables to continue before propagating errors
  • merge-delay-error( ) (clojure) — see mergeDelayError( )
  • mergeMap( ) * — see: flatMap( )
  • mergeMapIterable( ) — see: flatMapIterable( )
  • mergeWith( ) — instance version of merge( )
  • min( ) — emits the minimum value emitted by a source Observable (rxjava-math)
  • minBy( ) — emits the item emitted by the source Observable that has the minimum key value (rxjava-math)
  • mostRecent( ) — returns an iterable that always returns the item most recently emitted by the Observable
  • multicast( ) — represents an Observable as a Connectable Observable
  • never( ) — create an Observable that emits nothing at all
  • next( ) — returns an iterable that blocks until the Observable emits another item, then returns that item
  • nonEmpty( ) (scala) — see isEmpty( )
  • nth( ) (clojure) — see elementAt( ) and elementAtOrDefault( )
  • observeOn( ) — specify on which Scheduler a Subscriber should observe the Observable
  • ofType( ) — emit only those items from the source Observable that are of a particular class
  • onBackpressureBlock( ) — block the Observable's thread until the Observer is ready to accept more items from the Observable (⁇)
  • onBackpressureBuffer( ) — maintain a buffer of all emissions from the source Observable and emit them to downstream Subscribers according to the requests they generate
  • onBackpressureDrop( ) — drop emissions from the source Observable unless there is a pending request from a downstream Subscriber, in which case emit enough items to fulfill the request
  • onErrorFlatMap( ) — instructs an Observable to emit a sequence of items whenever it encounters an error (⁇)
  • onErrorResumeNext( ) — instructs an Observable to emit a sequence of items if it encounters an error
  • onErrorReturn( ) — instructs an Observable to emit a particular item when it encounters an error
  • onExceptionResumeNext( ) — instructs an Observable to continue emitting items after it encounters an exception (but not another variety of throwable)
  • orElse( ) (scala) — see defaultIfEmpty( )
  • parallel( ) — split the work done on the emissions from an Observable into multiple Observables each operating on its own parallel thread (⁇)
  • parallelMerge( ) — combine multiple Observables into smaller number of Observables (⁇)
  • pivot( ) — combine multiple sets of grouped observables so that they are arranged primarily by group rather than by set (⁇)
  • publish( ) — represents an Observable as a Connectable Observable
  • publishLast( ) — represent an Observable as a Connectable Observable that emits only the last item emitted by the source Observable (⁇)
  • range( ) — create an Observable that emits a range of sequential integers
  • reduce( ) — apply a function to each emitted item, sequentially, and emit only the final accumulated value
  • reductions( ) (clojure) — see scan( )
  • refCount( ) — makes a Connectable Observable behave like an ordinary Observable
  • repeat( ) — create an Observable that emits a particular item or sequence of items repeatedly
  • repeatWhen( ) — create an Observable that emits a particular item or sequence of items repeatedly, depending on the emissions of a second Observable
  • replay( ) — ensures that all Subscribers see the same sequence of emitted items, even if they subscribe after the Observable begins emitting the items
  • rest( ) (clojure) — see next( )
  • return( ) (clojure) — see just( )
  • retry( ) — if a source Observable emits an error, resubscribe to it in the hopes that it will complete without error
  • retrywhen( ) — if a source Observable emits an error, pass that error to another Observable to determine whether to resubscribe to the source
  • runAsync( ) — returns a StoppableObservable that emits multiple actions as generated by a specified Action on a Scheduler (rxjava-async)
  • sample( ) — emit the most recent items emitted by an Observable within periodic time intervals
  • scan( ) — apply a function to each item emitted by an Observable, sequentially, and emit each successive value
  • seq( ) (clojure) — see getIterator( )
  • sequenceEqual( ) — test the equality of sequences emitted by two Observables
  • sequenceEqualWith( ) (scala) — instance version of sequenceEqual( )
  • serialize( ) — force an Observable to make serialized calls and to be well-behaved
  • share( ) — see refCount( )
  • single( ) (BlockingObservable) — if the source Observable completes after emitting a single item, return that item, otherwise throw an exception
  • single( ) (Observable) — if the source Observable completes after emitting a single item, emit that item, otherwise notify of an exception
  • singleOption( ) (scala) — see singleOrDefault( ) (BlockingObservable)
  • singleOrDefault( ) (BlockingObservable) — if the source Observable completes after emitting a single item, return that item, otherwise return a default item
  • singleOrDefault( ) (Observable) — if the source Observable completes after emitting a single item, emit that item, otherwise emit a default item
  • singleOrElse( ) (scala) — see singleOrDefault( )
  • size( ) (scala) — see count( )
  • skip( ) — ignore the first n items emitted by an Observable
  • skipLast( ) — ignore the last n items emitted by an Observable
  • skipUntil( ) — discard items emitted by a source Observable until a second Observable emits an item, then emit the remainder of the source Observable's items
  • skipWhile( ) — discard items emitted by an Observable until a specified condition is false, then emit the remainder
  • sliding( ) (scala) — see window( )
  • slidingBuffer( ) (scala) — see buffer( )
  • split( ) (StringObservable) — converts an Observable of Strings into an Observable of Strings that treats the source sequence as a stream and splits it on a specified regex boundary
  • start( ) — create an Observable that emits the return value of a function (rxjava-async)
  • startCancellableFuture( ) — convert a function that returns Future into an Observable that emits that Future's return value in a way that monitors the subscription status of the Observable to determine whether to halt work on the Future (⁇)(rxjava-async)
  • startFuture( ) — convert a function that returns Future into an Observable that emits that Future's return value (rxjava-async)
  • startWith( ) — emit a specified sequence of items before beginning to emit the items from the Observable
  • stringConcat( ) (StringObservable) — converts an Observable that emits a sequence of strings into an Observable that emits a single string that concatenates them all
  • subscribeOn( ) — specify which Scheduler an Observable should use when its subscription is invoked
  • sumDouble( ) — adds the Doubles emitted by an Observable and emits this sum (rxjava-math)
  • sumFloat( ) — adds the Floats emitted by an Observable and emits this sum (rxjava-math)
  • sumInt( ) — adds the Integers emitted by an Observable and emits this sum (rxjava-math)
  • sumLong( ) — adds the Longs emitted by an Observable and emits this sum (rxjava-math)
  • switch( ) (scala) — see switchOnNext( )
  • switchCase( ) — emit the sequence from a particular Observable based on the results of an evaluation (contrib-computation-expressions)
  • switchMap( ) — transform the items emitted by an Observable into Observables, and mirror those items emitted by the most-recently transformed Observable
  • switchOnNext( ) — convert an Observable that emits Observables into a single Observable that emits the items emitted by the most-recently emitted of those Observables
  • synchronize( ) — see serialize( )
  • take( ) — emit only the first n items emitted by an Observable
  • takeFirst( ) — emit only the first item emitted by an Observable, or the first item that meets some condition
  • takeLast( ) — only emit the last n items emitted by an Observable
  • takeLastBuffer( ) — emit the last n items emitted by an Observable, as a single list item
  • takeRight( ) (scala) — see last( ) (Observable) or takeLast( )
  • takeUntil( ) — emits the items from the source Observable until a second Observable emits an item
  • takeWhile( ) — emit items emitted by an Observable as long as a specified condition is true, then skip the remainder
  • take-while( ) (clojure) — see takeWhile( )
  • then( ) — transform a series of Pattern objects via a Plan template (rxjava-joins)
  • throttleFirst( ) — emit the first items emitted by an Observable within periodic time intervals
  • throttleLast( ) — emit the most recent items emitted by an Observable within periodic time intervals
  • throttleWithTimeout( ) — only emit an item from the source Observable after a particular timespan has passed without the Observable emitting any other items
  • throw( ) (clojure) — see error( )
  • timeInterval( ) — emit the time lapsed between consecutive emissions of a source Observable
  • timeout( ) — emit items from a source Observable, but issue an exception if no item is emitted in a specified timespan
  • timer( ) — create an Observable that emits a single item after a given delay
  • timestamp( ) — attach a timestamp to every item emitted by an Observable
  • toAsync( ) — convert a function or Action into an Observable that executes the function and emits its return value (rxjava-async)
  • toBlocking( ) — transform an Observable into a BlockingObservable
  • toBlockingObservable( ) - see toBlocking( )
  • toFuture( ) — convert the Observable into a Future
  • toIterable( ) — convert the sequence emitted by the Observable into an Iterable
  • toIterator( ) — see getIterator( )
  • toList( ) — collect all items from an Observable and emit them as a single List
  • toMap( ) — convert the sequence of items emitted by an Observable into a map keyed by a specified key function
  • toMultimap( ) — convert the sequence of items emitted by an Observable into an ArrayList that is also a map keyed by a specified key function
  • toSeq( ) (scala) — see toList( )
  • toSortedList( ) — collect all items from an Observable and emit them as a single, sorted List
  • tumbling( ) (scala) — see window( )
  • tumblingBuffer( ) (scala) — see buffer( )
  • using( ) — create a disposable resource that has the same lifespan as an Observable
  • when( ) — convert a series of Plan objects into an Observable (rxjava-joins)
  • where( ) — see: filter( )
  • whileDo( ) — if a condition is true, emit the source Observable's sequence and then repeat the sequence as long as the condition remains true (contrib-computation-expressions)
  • window( ) — periodically subdivide items from an Observable into Observable windows and emit these windows rather than emitting the items one at a time
  • zip( ) — combine sets of items emitted by two or more Observables together via a specified function and emit items based on the results of this function
  • zipWith( ) — instance version of zip( )
  • zipWithIndex( ) (scala) — see zip( )
  • ++ (scala) — see concat( )
  • +: (scala) — see startWith( )

(⁇) — this proposed operator is not part of RxJava 1.0

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