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RxJava 2/3 interop library for supporting Java 8 features such as Optional, Stream and CompletableFuture
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RxJavaJdk8Interop

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RxJava 3.x: RxJava 3.x

RxJava 3 interop library for supporting Java 8 features such as Optional, Stream and CompletableFuture.

Release

compile 'com.github.akarnokd:rxjava3-jdk8-interop:3.0.0-RC3'

Examples

Javadocs: https://akarnokd.github.com/RxJavaJdk8Interop/javadoc/index.html

The main entry points are:

  • FlowableInterop
  • ObservableInterop
  • SingleInterop
  • MaybeInterop
  • CompletableInterop

Stream to RxJava

Note that java.util.stream.Stream can be consumed at most once and only synchronously.

Stream<T> stream = ...

Flowable<T> flow = FlowableInterop.fromStream(stream);

Observable<T> obs = ObservableInterop.fromStream(stream);

Optional to RxJava

Optional<T> opt = ...

Flowable<T> flow = FlowableInterop.fromOptional(opt);

Observable<T> obs = ObservableInterop.fromOptional(opt);

CompletionStage to RxJava

Note that cancelling the Subscription won't cancel the CompletionStage.

CompletionStage<T> cs = ...

Flowable<T> flow = FlowableInterop.fromFuture(cs);

Observable<T> flow = ObservableInterop.fromFuture(cs);

Using Stream Collectors

Flowable.range(1, 10)
.compose(FlowableInterop.collect(Collectors.toList()))
.test()
.assertResult(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));

Return the first/single/last element as a CompletionStage

CompletionStage<Integer> cs = Flowable.just(1)
.delay(1, TimeUnit.SECONDS)
// return first
.to(FlowableInterop.first());

// return single
// .to(FlowableInterop.single());

// return last
// .to(FlowableInterop.last());

cs.whenComplete((v, e) -> {
   System.out.println(v);
   System.out.println(e);
});

Return the only element as a CompletionStage

Single

CompletionStage<Integer> cs = Single.just(1)
.delay(1, TimeUnit.SECONDS)
.to(SingleInterop.get());

cs.whenComplete((v, e) -> {
   System.out.println(v);
   System.out.println(e);
});

Maybe

CompletionStage<Integer> cs = Maybe.just(1)
.delay(1, TimeUnit.SECONDS)
.to(MaybeInterop.get());

cs.whenComplete((v, e) -> {
   System.out.println(v);
   System.out.println(e);
});

Await completion as CompletionStage

Completable

CompletionStage<Void> cs = Completable.complete()
.delay(1, TimeUnit.SECONDS)
.to(CompletableInterop.await());

cs.whenComplete((v, e) -> {
   System.out.println(v);
   System.out.println(e);
});

Return the first/last element optionally

This is a blocking operation

Optional<Integer> opt = Flowable.just(1)
.to(FlowableInterop.firstElement());

System.out.println(opt.map(v -> v + 1).orElse(-1));

Convert to Java Stream

This is a blocking operation. Closing the stream will cancel the RxJava sequence.

Flowable.range(1, 10)
.to(FlowableInterop.toStream())
.parallel()
.map(v -> v + 1)
.forEach(System.out::println);

FlatMap Java Streams

Note that since consuming a stream is practically blocking, there is no need for a maxConcurrency parameter.

Flowable.range(1, 5)
.compose(FlowableInterop.flatMapStream(v -> Arrays.asList(v, v + 1).stream()))
.test()
.assertResult(1, 2, 2, 3, 3, 4, 4, 5, 5, 6);

Map based on Java Optional

Flowable.range(1, 5)
.compose(FlowableInterop.mapOptional(v -> v % 2 == 0 ? Optional.of(v) : Optional.empty()))
.test()
.assertResult(2, 4);
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