Package io.helidon.common.reactive

Interface Single<T>

Type Parameters:

T - item type

All Superinterfaces:

Flow.Publisher<T>, Subscribable<T>

public interface Single<T>
extends Subscribable<T>

Single item publisher utility.

Method Summary

Modifier and Type	Method	Description
static <T> Single<T>	empty()	Get a Single instance that completes immediately.
static <T> Single<T>	error(Throwable error)	Create a Single instance that reports the given given exception to its subscriber(s).
static <T> Single<T>	from(Flow.Publisher<T> source)	Create a Single instance that publishes the first and only item received from the given publisher.
default T	get()	Short-hand for toFuture().toCompletableFuture().get().
default T	get(long timeout, TimeUnit unit)	Short-hand for toFuture().toCompletableFuture().get().
static <T> Single<T>	just(T item)	Create a Single instance that publishes the given item to its subscriber(s).
default <U> Single<U>	map(Mapper<T,U> mapper)	Map this Single instance to a new Single of another type using the given Mapper.
default <U> Multi<U>	mapMany(Mapper<T,Flow.Publisher<U>> mapper)	Map this Single instance to a publisher using the given Mapper.
static <T> Single<T>	never()	Get a Single instance that never completes.
default CompletionStage<T>	toStage()	Exposes this Single instance as a CompletionStage.

Methods inherited from interface io.helidon.common.reactive.Flow.Publisher

subscribe

Methods inherited from interface io.helidon.common.reactive.Subscribable

subscribe, subscribe, subscribe, subscribe

Method Detail

map

default <U> Single<U> map(Mapper<T,U> mapper)

Map this Single instance to a new Single of another type using the given Mapper.

Type Parameters:

U - mapped item type

Parameters:

mapper - mapper

Returns:

Single

Throws:

NullPointerException - if mapper is null

mapMany

default <U> Multi<U> mapMany(Mapper<T,Flow.Publisher<U>> mapper)

Map this Single instance to a publisher using the given Mapper.

Type Parameters:

U - mapped items type

Parameters:

mapper - mapper

Returns:

Publisher

Throws:

NullPointerException - if mapper is null

toStage

default CompletionStage<T> toStage()

Exposes this Single instance as a CompletionStage. Note that if this Single completes without a value, the resulting CompletionStage will be completed exceptionally with an IllegalStateException

Returns:

CompletionStage

get

default T get()
       throws InterruptedException,
              ExecutionException

Short-hand for toFuture().toCompletableFuture().get().

Returns:

T

Throws:

InterruptedException - if the current thread was interrupted while waiting

ExecutionException - if the future completed exceptionally

get

default T get(long timeout,
              TimeUnit unit)
       throws InterruptedException,
              ExecutionException,
              TimeoutException

Short-hand for toFuture().toCompletableFuture().get().

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

T

Throws:

InterruptedException - if the current thread was interrupted while waiting

ExecutionException - if the future completed exceptionally

TimeoutException - if the wait timed out

from

static <T> Single<T> from(Flow.Publisher<T> source)

Create a Single instance that publishes the first and only item received from the given publisher. Note that if the publisher publishes more than one item, the resulting Single will hold an error. Use Multi.first() instead in order to get the first item of a publisher that may publish more than one item.

Type Parameters:

T - item type

Parameters:

source - source publisher

Returns:

Single

Throws:

NullPointerException - if source is null

just

static <T> Single<T> just(T item)

Create a Single instance that publishes the given item to its subscriber(s).

Type Parameters:

T - item type

Parameters:

item - item to publish

Returns:

Single

Throws:

NullPointerException - if item is null

error

static <T> Single<T> error(Throwable error)

Create a Single instance that reports the given given exception to its subscriber(s). The exception is reported by invoking Flow.Subscriber.onError(java.lang.Throwable) when Flow.Publisher.subscribe(Subscriber) is called.

Type Parameters:

T - item type

Parameters:

error - exception to hold

Returns:

Single

Throws:

NullPointerException - if error is null

empty

static <T> Single<T> empty()

Get a Single instance that completes immediately.

Type Parameters:

T - item type

Returns:

Single

never

static <T> Single<T> never()

Get a Single instance that never completes.

Type Parameters:

T - item type

Returns:

Single