compact1, compact2, compact3

java.util.concurrent

Interface CompletionStage<T>

All Known Implementing Classes:

CompletableFuture

public interface CompletionStage<T>

A stage of a possibly asynchronous computation, that performs an action or computes a value when another CompletionStage completes. A stage completes upon termination of its computation, but this may in turn trigger other dependent stages. The functionality defined in this interface takes only a few basic forms, which expand out to a larger set of methods to capture a range of usage styles:

• The computation performed by a stage may be expressed as a Function, Consumer, or Runnable (using methods with names including apply, accept, or run, respectively) depending on whether it requires arguments and/or produces results. For example, stage.thenApply(x -> square(x)).thenAccept(x -> System.out.print(x)).thenRun(() -> System.out.println()). An additional form (compose) applies functions of stages themselves, rather than their results.
• One stage's execution may be triggered by completion of a single stage, or both of two stages, or either of two stages. Dependencies on a single stage are arranged using methods with prefix then. Those triggered by completion of both of two stages may combine their results or effects, using correspondingly named methods. Those triggered by either of two stages make no guarantees about which of the results or effects are used for the dependent stage's computation.
• Dependencies among stages control the triggering of computations, but do not otherwise guarantee any particular ordering. Additionally, execution of a new stage's computations may be arranged in any of three ways: default execution, default asynchronous execution (using methods with suffix async that employ the stage's default asynchronous execution facility), or custom (via a supplied Executor). The execution properties of default and async modes are specified by CompletionStage implementations, not this interface. Methods with explicit Executor arguments may have arbitrary execution properties, and might not even support concurrent execution, but are arranged for processing in a way that accommodates asynchrony.
• Two method forms support processing whether the triggering stage completed normally or exceptionally: Method whenComplete allows injection of an action regardless of outcome, otherwise preserving the outcome in its completion. Method handle additionally allows the stage to compute a replacement result that may enable further processing by other dependent stages. In all other cases, if a stage's computation terminates abruptly with an (unchecked) exception or error, then all dependent stages requiring its completion complete exceptionally as well, with a CompletionException holding the exception as its cause. If a stage is dependent on both of two stages, and both complete exceptionally, then the CompletionException may correspond to either one of these exceptions. If a stage is dependent on either of two others, and only one of them completes exceptionally, no guarantees are made about whether the dependent stage completes normally or exceptionally. In the case of method whenComplete, when the supplied action itself encounters an exception, then the stage exceptionally completes with this exception if not already completed exceptionally.

All methods adhere to the above triggering, execution, and exceptional completion specifications (which are not repeated in individual method specifications). Additionally, while arguments used to pass a completion result (that is, for parameters of type T) for methods accepting them may be null, passing a null value for any other parameter will result in a NullPointerException being thrown.

This interface does not define methods for initially creating, forcibly completing normally or exceptionally, probing completion status or results, or awaiting completion of a stage. Implementations of CompletionStage may provide means of achieving such effects, as appropriate. Method toCompletableFuture() enables interoperability among different implementations of this interface by providing a common conversion type.

Since:

1.8

Method Summary

Modifier and Type	Method and Description
CompletionStage<Void>	acceptEither(CompletionStage<? extends T> other, Consumer<? super T> action) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed with the corresponding result as argument to the supplied action.
CompletionStage<Void>	acceptEitherAsync(CompletionStage<? extends T> other, Consumer<? super T> action) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the corresponding result as argument to the supplied action.
CompletionStage<Void>	acceptEitherAsync(CompletionStage<? extends T> other, Consumer<? super T> action, Executor executor) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using the supplied executor, with the corresponding result as argument to the supplied function.
<U> CompletionStage<U>	applyToEither(CompletionStage<? extends T> other, Function<? super T,U> fn) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed with the corresponding result as argument to the supplied function.
<U> CompletionStage<U>	applyToEitherAsync(CompletionStage<? extends T> other, Function<? super T,U> fn) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the corresponding result as argument to the supplied function.
<U> CompletionStage<U>	applyToEitherAsync(CompletionStage<? extends T> other, Function<? super T,U> fn, Executor executor) Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using the supplied executor, with the corresponding result as argument to the supplied function.
CompletionStage<T>	exceptionally(Function<Throwable,? extends T> fn) Returns a new CompletionStage that, when this stage completes exceptionally, is executed with this stage's exception as the argument to the supplied function.
<U> CompletionStage<U>	handle(BiFunction<? super T,Throwable,? extends U> fn) Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed with this stage's result and exception as arguments to the supplied function.
<U> CompletionStage<U>	handleAsync(BiFunction<? super T,Throwable,? extends U> fn) Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed using this stage's default asynchronous execution facility, with this stage's result and exception as arguments to the supplied function.
<U> CompletionStage<U>	handleAsync(BiFunction<? super T,Throwable,? extends U> fn, Executor executor) Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed using the supplied executor, with this stage's result and exception as arguments to the supplied function.
CompletionStage<Void>	runAfterBoth(CompletionStage<?> other, Runnable action) Returns a new CompletionStage that, when this and the other given stage both complete normally, executes the given action.
CompletionStage<Void>	runAfterBothAsync(CompletionStage<?> other, Runnable action) Returns a new CompletionStage that, when this and the other given stage complete normally, executes the given action using this stage's default asynchronous execution facility.
CompletionStage<Void>	runAfterBothAsync(CompletionStage<?> other, Runnable action, Executor executor) Returns a new CompletionStage that, when this and the other given stage complete normally, executes the given action using the supplied executor See the CompletionStage documentation for rules covering exceptional completion.
CompletionStage<Void>	runAfterEither(CompletionStage<?> other, Runnable action) Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action.
CompletionStage<Void>	runAfterEitherAsync(CompletionStage<?> other, Runnable action) Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action using this stage's default asynchronous execution facility.
CompletionStage<Void>	runAfterEitherAsync(CompletionStage<?> other, Runnable action, Executor executor) Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action using supplied executor.
CompletionStage<Void>	thenAccept(Consumer<? super T> action) Returns a new CompletionStage that, when this stage completes normally, is executed with this stage's result as the argument to the supplied action.
CompletionStage<Void>	thenAcceptAsync(Consumer<? super T> action) Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage's result as the argument to the supplied action.
CompletionStage<Void>	thenAcceptAsync(Consumer<? super T> action, Executor executor) Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied action.
<U> CompletionStage<Void>	thenAcceptBoth(CompletionStage<? extends U> other, BiConsumer<? super T,? super U> action) Returns a new CompletionStage that, when this and the other given stage both complete normally, is executed with the two results as arguments to the supplied action.
<U> CompletionStage<Void>	thenAcceptBothAsync(CompletionStage<? extends U> other, BiConsumer<? super T,? super U> action) Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the two results as arguments to the supplied action.
<U> CompletionStage<Void>	thenAcceptBothAsync(CompletionStage<? extends U> other, BiConsumer<? super T,? super U> action, Executor executor) Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using the supplied executor, with the two results as arguments to the supplied function.
<U> CompletionStage<U>	thenApply(Function<? super T,? extends U> fn) Returns a new CompletionStage that, when this stage completes normally, is executed with this stage's result as the argument to the supplied function.
<U> CompletionStage<U>	thenApplyAsync(Function<? super T,? extends U> fn) Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage's result as the argument to the supplied function.
<U> CompletionStage<U>	thenApplyAsync(Function<? super T,? extends U> fn, Executor executor) Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied function.
<U,V> CompletionStage<V>	thenCombine(CompletionStage<? extends U> other, BiFunction<? super T,? super U,? extends V> fn) Returns a new CompletionStage that, when this and the other given stage both complete normally, is executed with the two results as arguments to the supplied function.
<U,V> CompletionStage<V>	thenCombineAsync(CompletionStage<? extends U> other, BiFunction<? super T,? super U,? extends V> fn) Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the two results as arguments to the supplied function.
<U,V> CompletionStage<V>	thenCombineAsync(CompletionStage<? extends U> other, BiFunction<? super T,? super U,? extends V> fn, Executor executor) Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using the supplied executor, with the two results as arguments to the supplied function.
<U> CompletionStage<U>	thenCompose(Function<? super T,? extends CompletionStage<U>> fn) Returns a new CompletionStage that, when this stage completes normally, is executed with this stage as the argument to the supplied function.
<U> CompletionStage<U>	thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn) Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage as the argument to the supplied function.
<U> CompletionStage<U>	thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn, Executor executor) Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied function.
CompletionStage<Void>	thenRun(Runnable action) Returns a new CompletionStage that, when this stage completes normally, executes the given action.
CompletionStage<Void>	thenRunAsync(Runnable action) Returns a new CompletionStage that, when this stage completes normally, executes the given action using this stage's default asynchronous execution facility.
CompletionStage<Void>	thenRunAsync(Runnable action, Executor executor) Returns a new CompletionStage that, when this stage completes normally, executes the given action using the supplied Executor.
CompletableFuture<T>	toCompletableFuture() Returns a CompletableFuture maintaining the same completion properties as this stage.
CompletionStage<T>	whenComplete(BiConsumer<? super T,? super Throwable> action) Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes the given action with the result (or null if none) and the exception (or null if none) of this stage.
CompletionStage<T>	whenCompleteAsync(BiConsumer<? super T,? super Throwable> action) Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes the given action executes the given action using this stage's default asynchronous execution facility, with the result (or null if none) and the exception (or null if none) of this stage as arguments.
CompletionStage<T>	whenCompleteAsync(BiConsumer<? super T,? super Throwable> action, Executor executor) Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes using the supplied Executor, the given action with the result (or null if none) and the exception (or null if none) of this stage as arguments.

Method Detail

thenApply

<U> CompletionStage<U> thenApply(Function<? super T,? extends U> fn)

Returns a new CompletionStage that, when this stage completes normally, is executed with this stage's result as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

thenApplyAsync

<U> CompletionStage<U> thenApplyAsync(Function<? super T,? extends U> fn)

Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage's result as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

thenApplyAsync

<U> CompletionStage<U> thenApplyAsync(Function<? super T,? extends U> fn,
                                      Executor executor)

Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenAccept

CompletionStage<Void> thenAccept(Consumer<? super T> action)

Returns a new CompletionStage that, when this stage completes normally, is executed with this stage's result as the argument to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptAsync

CompletionStage<Void> thenAcceptAsync(Consumer<? super T> action)

Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage's result as the argument to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptAsync

CompletionStage<Void> thenAcceptAsync(Consumer<? super T> action,
                                      Executor executor)

Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenRun

CompletionStage<Void> thenRun(Runnable action)

Returns a new CompletionStage that, when this stage completes normally, executes the given action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenRunAsync

CompletionStage<Void> thenRunAsync(Runnable action)

Returns a new CompletionStage that, when this stage completes normally, executes the given action using this stage's default asynchronous execution facility. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenRunAsync

CompletionStage<Void> thenRunAsync(Runnable action,
                                   Executor executor)

Returns a new CompletionStage that, when this stage completes normally, executes the given action using the supplied Executor. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenCombine

<U,V> CompletionStage<V> thenCombine(CompletionStage<? extends U> other,
                                     BiFunction<? super T,? super U,? extends V> fn)

Returns a new CompletionStage that, when this and the other given stage both complete normally, is executed with the two results as arguments to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the other CompletionStage's result

V - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

thenCombineAsync

<U,V> CompletionStage<V> thenCombineAsync(CompletionStage<? extends U> other,
                                          BiFunction<? super T,? super U,? extends V> fn)

Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the two results as arguments to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the other CompletionStage's result

V - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

thenCombineAsync

<U,V> CompletionStage<V> thenCombineAsync(CompletionStage<? extends U> other,
                                          BiFunction<? super T,? super U,? extends V> fn,
                                          Executor executor)

Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using the supplied executor, with the two results as arguments to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the other CompletionStage's result

V - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenAcceptBoth

<U> CompletionStage<Void> thenAcceptBoth(CompletionStage<? extends U> other,
                                         BiConsumer<? super T,? super U> action)

Returns a new CompletionStage that, when this and the other given stage both complete normally, is executed with the two results as arguments to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the other CompletionStage's result

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptBothAsync

<U> CompletionStage<Void> thenAcceptBothAsync(CompletionStage<? extends U> other,
                                              BiConsumer<? super T,? super U> action)

Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the two results as arguments to the supplied action.

Type Parameters:

U - the type of the other CompletionStage's result

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptBothAsync

<U> CompletionStage<Void> thenAcceptBothAsync(CompletionStage<? extends U> other,
                                              BiConsumer<? super T,? super U> action,
                                              Executor executor)

Returns a new CompletionStage that, when this and the other given stage complete normally, is executed using the supplied executor, with the two results as arguments to the supplied function.

Type Parameters:

U - the type of the other CompletionStage's result

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

runAfterBoth

CompletionStage<Void> runAfterBoth(CompletionStage<?> other,
                                   Runnable action)

Returns a new CompletionStage that, when this and the other given stage both complete normally, executes the given action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterBothAsync

CompletionStage<Void> runAfterBothAsync(CompletionStage<?> other,
                                        Runnable action)

Returns a new CompletionStage that, when this and the other given stage complete normally, executes the given action using this stage's default asynchronous execution facility. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterBothAsync

CompletionStage<Void> runAfterBothAsync(CompletionStage<?> other,
                                        Runnable action,
                                        Executor executor)

Returns a new CompletionStage that, when this and the other given stage complete normally, executes the given action using the supplied executor See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

applyToEither

<U> CompletionStage<U> applyToEither(CompletionStage<? extends T> other,
                                     Function<? super T,U> fn)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed with the corresponding result as argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

applyToEitherAsync

<U> CompletionStage<U> applyToEitherAsync(CompletionStage<? extends T> other,
                                          Function<? super T,U> fn)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the corresponding result as argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

applyToEitherAsync

<U> CompletionStage<U> applyToEitherAsync(CompletionStage<? extends T> other,
                                          Function<? super T,U> fn,
                                          Executor executor)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using the supplied executor, with the corresponding result as argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the function's return type

Parameters:

other - the other CompletionStage

fn - the function to use to compute the value of the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

acceptEither

CompletionStage<Void> acceptEither(CompletionStage<? extends T> other,
                                   Consumer<? super T> action)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed with the corresponding result as argument to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

acceptEitherAsync

CompletionStage<Void> acceptEitherAsync(CompletionStage<? extends T> other,
                                        Consumer<? super T> action)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using this stage's default asynchronous execution facility, with the corresponding result as argument to the supplied action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

acceptEitherAsync

CompletionStage<Void> acceptEitherAsync(CompletionStage<? extends T> other,
                                        Consumer<? super T> action,
                                        Executor executor)

Returns a new CompletionStage that, when either this or the other given stage complete normally, is executed using the supplied executor, with the corresponding result as argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

runAfterEither

CompletionStage<Void> runAfterEither(CompletionStage<?> other,
                                     Runnable action)

Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterEitherAsync

CompletionStage<Void> runAfterEitherAsync(CompletionStage<?> other,
                                          Runnable action)

Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action using this stage's default asynchronous execution facility. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterEitherAsync

CompletionStage<Void> runAfterEitherAsync(CompletionStage<?> other,
                                          Runnable action,
                                          Executor executor)

Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action using supplied executor. See the CompletionStage documentation for rules covering exceptional completion.

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenCompose

<U> CompletionStage<U> thenCompose(Function<? super T,? extends CompletionStage<U>> fn)

Returns a new CompletionStage that, when this stage completes normally, is executed with this stage as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the returned CompletionStage's result

Parameters:

fn - the function returning a new CompletionStage

Returns:

the CompletionStage

thenComposeAsync

<U> CompletionStage<U> thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn)

Returns a new CompletionStage that, when this stage completes normally, is executed using this stage's default asynchronous execution facility, with this stage as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the returned CompletionStage's result

Parameters:

fn - the function returning a new CompletionStage

Returns:

the CompletionStage

thenComposeAsync

<U> CompletionStage<U> thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn,
                                        Executor executor)

Returns a new CompletionStage that, when this stage completes normally, is executed using the supplied Executor, with this stage's result as the argument to the supplied function. See the CompletionStage documentation for rules covering exceptional completion.

Type Parameters:

U - the type of the returned CompletionStage's result

Parameters:

fn - the function returning a new CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the CompletionStage

exceptionally

CompletionStage<T> exceptionally(Function<Throwable,? extends T> fn)

Returns a new CompletionStage that, when this stage completes exceptionally, is executed with this stage's exception as the argument to the supplied function. Otherwise, if this stage completes normally, then the returned stage also completes normally with the same value.

Parameters:

fn - the function to use to compute the value of the returned CompletionStage if this CompletionStage completed exceptionally

Returns:

the new CompletionStage

whenComplete

CompletionStage<T> whenComplete(BiConsumer<? super T,? super Throwable> action)

Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes the given action with the result (or null if none) and the exception (or null if none) of this stage.

Parameters:

action - the action to perform

Returns:

the new CompletionStage

whenCompleteAsync

CompletionStage<T> whenCompleteAsync(BiConsumer<? super T,? super Throwable> action)

Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes the given action executes the given action using this stage's default asynchronous execution facility, with the result (or null if none) and the exception (or null if none) of this stage as arguments.

Parameters:

action - the action to perform

Returns:

the new CompletionStage

whenCompleteAsync

CompletionStage<T> whenCompleteAsync(BiConsumer<? super T,? super Throwable> action,
                                     Executor executor)

Returns a new CompletionStage with the same result or exception as this stage, and when this stage completes, executes using the supplied Executor, the given action with the result (or null if none) and the exception (or null if none) of this stage as arguments.

Parameters:

action - the action to perform

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

handle

<U> CompletionStage<U> handle(BiFunction<? super T,Throwable,? extends U> fn)

Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed with this stage's result and exception as arguments to the supplied function. The given function is invoked with the result (or null if none) and the exception (or null if none) of this stage when complete as arguments.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

handleAsync

<U> CompletionStage<U> handleAsync(BiFunction<? super T,Throwable,? extends U> fn)

Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed using this stage's default asynchronous execution facility, with this stage's result and exception as arguments to the supplied function. The given function is invoked with the result (or null if none) and the exception (or null if none) of this stage when complete as arguments.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

Returns:

the new CompletionStage

handleAsync

<U> CompletionStage<U> handleAsync(BiFunction<? super T,Throwable,? extends U> fn,
                                   Executor executor)

Returns a new CompletionStage that, when this stage completes either normally or exceptionally, is executed using the supplied executor, with this stage's result and exception as arguments to the supplied function. The given function is invoked with the result (or null if none) and the exception (or null if none) of this stage when complete as arguments.

Type Parameters:

U - the function's return type

Parameters:

fn - the function to use to compute the value of the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

toCompletableFuture

CompletableFuture<T> toCompletableFuture()

Returns a CompletableFuture maintaining the same completion properties as this stage. If this stage is already a CompletableFuture, this method may return this stage itself. Otherwise, invocation of this method may be equivalent in effect to thenApply(x -> x), but returning an instance of type CompletableFuture. A CompletionStage implementation that does not choose to interoperate with others may throw UnsupportedOperationException.

Returns:

the CompletableFuture

Throws:

UnsupportedOperationException - if this implementation does not interoperate with CompletableFuture