hu.akarnokd.rxjava2.interop

Class ObservableInterop

java.lang.Object

hu.akarnokd.rxjava2.interop.ObservableInterop

public final class ObservableInterop
extends java.lang.Object

Utility methods, sources and operators supporting RxJava 2 and the Jdk 8 API interoperation.

Since:

0.1.0

Method Summary

Modifier and Type	Method and Description
static <T,A,R> io.reactivex.ObservableTransformer<T,R>	collect(java.util.stream.Collector<T,A,R> collector) Collect the elements of the Observable via the help of Collector and its callback functions.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>>	first() Returns a CompletionStage that signals the first element of the Observable or a NoSuchElementException if the Observable is empty.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.Optional<T>>	firstElement() Block until the source Observable emits its first item and return that as Optional.
static <T,R> io.reactivex.ObservableTransformer<T,R>	flatMapStream(io.reactivex.functions.Function<? super T,? extends java.util.stream.Stream<R>> mapper) Map each value of the upstream into a Stream and flatten them into a single sequence.
static <T> io.reactivex.Observable<T>	fromFuture(java.util.concurrent.CompletionStage<T> cs) Create a Observable that signals the terminal value or error of the given CompletionStage.
static <T> io.reactivex.Observable<T>	fromOptional(java.util.Optional<T> opt) Returns a Observable for the value (or lack of) in the given Optional.
static <T> io.reactivex.Observable<T>	fromStream(java.util.stream.Stream<T> stream) Wrap a Stream into a Observable.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>>	last() Returns a CompletionStage that emits the last element of the Observable or NoSuchElementException if the Observable is empty.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.Optional<T>>	lastElement() Block until the source Observable completes and return its last value as Optional.
static <T,R> io.reactivex.ObservableTransformer<T,R>	mapOptional(io.reactivex.functions.Function<? super T,java.util.Optional<R>> mapper) Maps the upstream value into an optional and extracts its optional value to be emitted towards the downstream if present.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>>	single() Returns a CompletionStage that signals the single element of the Observable, IllegalArgumentException if the Observable is longer than 1 element or a NoSuchElementException if the Observable is empty.
static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.stream.Stream<T>>	toStream() Returns a blocking Stream of the elements of the Observable.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

fromStream

public static <T> io.reactivex.Observable<T> fromStream(java.util.stream.Stream<T> stream)

Wrap a Stream into a Observable.

Note that Streams can only be consumed once and non-concurrently.

Type Parameters:

T - the value type

Parameters:

stream - the source Stream

Returns:

the new Observable instance

fromOptional

public static <T> io.reactivex.Observable<T> fromOptional(java.util.Optional<T> opt)

Returns a Observable for the value (or lack of) in the given Optional.

Type Parameters:

T - the value type

Parameters:

opt - the optional to wrap

Returns:

the new Observable instance

fromFuture

public static <T> io.reactivex.Observable<T> fromFuture(java.util.concurrent.CompletionStage<T> cs)

Create a Observable that signals the terminal value or error of the given CompletionStage.

Cancelling the Observable subscription doesn't cancel the CompletionStage.

Type Parameters:

T - the value type

Parameters:

cs - the CompletionStage instance

Returns:

the new Observable instance

collect

public static <T,A,R> io.reactivex.ObservableTransformer<T,R> collect(java.util.stream.Collector<T,A,R> collector)

Collect the elements of the Observable via the help of Collector and its callback functions.

Type Parameters:

T - the upstream value type

A - the accumulated type

R - the result type

Parameters:

collector - the Collector object providing the callbacks

Returns:

the Transformer instance to be used with Observable.compose()

first

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>> first()

Returns a CompletionStage that signals the first element of the Observable or a NoSuchElementException if the Observable is empty.

Type Parameters:

T - the value type

Returns:

the Function to be used via Observable.to.

single

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>> single()

Returns a CompletionStage that signals the single element of the Observable, IllegalArgumentException if the Observable is longer than 1 element or a NoSuchElementException if the Observable is empty.

Type Parameters:

T - the value type

Returns:

the Function to be used with Observable.to.

last

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.concurrent.CompletionStage<T>> last()

Returns a CompletionStage that emits the last element of the Observable or NoSuchElementException if the Observable is empty.

Type Parameters:

T - the value type

Returns:

the Function to be used with Observable.to.

toStream

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.stream.Stream<T>> toStream()

Returns a blocking Stream of the elements of the Observable.

Closing the Stream will cancel the flow.

Type Parameters:

T - the value type

Returns:

the Function to be used with Observable.to.

firstElement

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.Optional<T>> firstElement()

Block until the source Observable emits its first item and return that as Optional.

Type Parameters:

T - the value type

Returns:

the converter Function to be used with Observable.to().

lastElement

public static <T> io.reactivex.functions.Function<io.reactivex.Observable<T>,java.util.Optional<T>> lastElement()

Block until the source Observable completes and return its last value as Optional.

Type Parameters:

T - the value type

Returns:

the converter Function to be used with Observable.to().

mapOptional

public static <T,R> io.reactivex.ObservableTransformer<T,R> mapOptional(io.reactivex.functions.Function<? super T,java.util.Optional<R>> mapper)

Maps the upstream value into an optional and extracts its optional value to be emitted towards the downstream if present.

Type Parameters:

T - the upstream value type

R - the result value type

Parameters:

mapper - the function receiving the upstream value and should return an Optional

Returns:

the Transformer instance to be used with Observable.compose()

flatMapStream

public static <T,R> io.reactivex.ObservableTransformer<T,R> flatMapStream(io.reactivex.functions.Function<? super T,? extends java.util.stream.Stream<R>> mapper)

Map each value of the upstream into a Stream and flatten them into a single sequence.

Type Parameters:

T - the input value type

R - the Stream type

Parameters:

mapper - the function that returns a Stream for each upstream value

Returns:

the new Transformer instance