java8.util.concurrent

Class CompletableFuture<T>

java.lang.Object

java8.util.concurrent.CompletableFuture<T>

All Implemented Interfaces:

java.util.concurrent.Future<T>, CompletionStage<T>

public class CompletableFuture<T>
extends java.lang.Object
implements java.util.concurrent.Future<T>, CompletionStage<T>

A Future that may be explicitly completed (setting its value and status), and may be used as a CompletionStage, supporting dependent functions and actions that trigger upon its completion.

When two or more threads attempt to complete, completeExceptionally, or cancel a CompletableFuture, only one of them succeeds.

In addition to these and related methods for directly manipulating status and results, CompletableFuture implements interface CompletionStage with the following policies:

• Actions supplied for dependent completions of non-async methods may be performed by the thread that completes the current CompletableFuture, or by any other caller of a completion method.
• All async methods without an explicit Executor argument are performed using the ForkJoinPool.commonPool() (unless it does not support a parallelism level of at least two, in which case, a new Thread is used). To simplify monitoring, debugging, and tracking, all generated asynchronous tasks are instances of the marker interface CompletableFuture.AsynchronousCompletionTask.
• All CompletionStage methods are implemented independently of other public methods, so the behavior of one method is not impacted by overrides of others in subclasses.

CompletableFuture also implements Future with the following policies:

• Since (unlike FutureTask) this class has no direct control over the computation that causes it to be completed, cancellation is treated as just another form of exceptional completion. Method cancel has the same effect as completeExceptionally(new CancellationException()). Method isCompletedExceptionally() can be used to determine if a CompletableFuture completed in any exceptional fashion.
• In case of exceptional completion with a CompletionException, methods get() and get(long, TimeUnit) throw an ExecutionException with the same cause as held in the corresponding CompletionException. To simplify usage in most contexts, this class also defines methods join() and getNow(T) that instead throw the CompletionException directly in these cases.

Since:

1.8

Author:

Doug Lea

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CompletableFuture.AsynchronousCompletionTask A marker interface identifying asynchronous tasks produced by async methods.

Constructor Summary

Constructors

Constructor and Description
CompletableFuture() Creates a new incomplete CompletableFuture.

Method Summary

Modifier and Type	Method and Description
CompletableFuture<java.lang.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.
CompletableFuture<java.lang.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.
CompletableFuture<java.lang.Void>	acceptEitherAsync(CompletionStage<? extends T> other, Consumer<? super T> action, java.util.concurrent.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.
static CompletableFuture<java.lang.Void>	allOf(CompletableFuture<?>... cfs) Returns a new CompletableFuture that is completed when all of the given CompletableFutures complete.
static CompletableFuture<java.lang.Object>	anyOf(CompletableFuture<?>... cfs) Returns a new CompletableFuture that is completed when any of the given CompletableFutures complete, with the same result.
<U> CompletableFuture<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> CompletableFuture<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> CompletableFuture<U>	applyToEitherAsync(CompletionStage<? extends T> other, Function<? super T,U> fn, java.util.concurrent.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.
boolean	cancel(boolean mayInterruptIfRunning) If not already completed, completes this CompletableFuture with a CancellationException.
boolean	complete(T value) If not already completed, sets the value returned by get() and related methods to the given value.
static <U> CompletableFuture<U>	completedFuture(U value) Returns a new CompletableFuture that is already completed with the given value.
boolean	completeExceptionally(java.lang.Throwable ex) If not already completed, causes invocations of get() and related methods to throw the given exception.
CompletableFuture<T>	exceptionally(Function<java.lang.Throwable,? extends T> fn) Returns a new CompletableFuture that is completed when this CompletableFuture completes, with the result of the given function of the exception triggering this CompletableFuture's completion when it completes exceptionally; otherwise, if this CompletableFuture completes normally, then the returned CompletableFuture also completes normally with the same value.
T	get() Waits if necessary for this future to complete, and then returns its result.
T	get(long timeout, java.util.concurrent.TimeUnit unit) Waits if necessary for at most the given time for this future to complete, and then returns its result, if available.
T	getNow(T valueIfAbsent) Returns the result value (or throws any encountered exception) if completed, else returns the given valueIfAbsent.
int	getNumberOfDependents() Returns the estimated number of CompletableFutures whose completions are awaiting completion of this CompletableFuture.
<U> CompletableFuture<U>	handle(BiFunction<? super T,java.lang.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> CompletableFuture<U>	handleAsync(BiFunction<? super T,java.lang.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> CompletableFuture<U>	handleAsync(BiFunction<? super T,java.lang.Throwable,? extends U> fn, java.util.concurrent.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.
boolean	isCancelled() Returns true if this CompletableFuture was cancelled before it completed normally.
boolean	isCompletedExceptionally() Returns true if this CompletableFuture completed exceptionally, in any way.
boolean	isDone() Returns true if completed in any fashion: normally, exceptionally, or via cancellation.
T	join() Returns the result value when complete, or throws an (unchecked) exception if completed exceptionally.
void	obtrudeException(java.lang.Throwable ex) Forcibly causes subsequent invocations of method get() and related methods to throw the given exception, whether or not already completed.
void	obtrudeValue(T value) Forcibly sets or resets the value subsequently returned by method get() and related methods, whether or not already completed.
CompletableFuture<java.lang.Void>	runAfterBoth(CompletionStage<?> other, java.lang.Runnable action) Returns a new CompletionStage that, when this and the other given stage both complete normally, executes the given action.
CompletableFuture<java.lang.Void>	runAfterBothAsync(CompletionStage<?> other, java.lang.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.
CompletableFuture<java.lang.Void>	runAfterBothAsync(CompletionStage<?> other, java.lang.Runnable action, java.util.concurrent.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.
CompletableFuture<java.lang.Void>	runAfterEither(CompletionStage<?> other, java.lang.Runnable action) Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action.
CompletableFuture<java.lang.Void>	runAfterEitherAsync(CompletionStage<?> other, java.lang.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.
CompletableFuture<java.lang.Void>	runAfterEitherAsync(CompletionStage<?> other, java.lang.Runnable action, java.util.concurrent.Executor executor) Returns a new CompletionStage that, when either this or the other given stage complete normally, executes the given action using supplied executor.
static CompletableFuture<java.lang.Void>	runAsync(java.lang.Runnable runnable) Returns a new CompletableFuture that is asynchronously completed by a task running in the ForkJoinPool.commonPool() after it runs the given action.
static CompletableFuture<java.lang.Void>	runAsync(java.lang.Runnable runnable, java.util.concurrent.Executor executor) Returns a new CompletableFuture that is asynchronously completed by a task running in the given executor after it runs the given action.
static <U> CompletableFuture<U>	supplyAsync(Supplier<U> supplier) Returns a new CompletableFuture that is asynchronously completed by a task running in the ForkJoinPool.commonPool() with the value obtained by calling the given Supplier.
static <U> CompletableFuture<U>	supplyAsync(Supplier<U> supplier, java.util.concurrent.Executor executor) Returns a new CompletableFuture that is asynchronously completed by a task running in the given executor with the value obtained by calling the given Supplier.
CompletableFuture<java.lang.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.
CompletableFuture<java.lang.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.
CompletableFuture<java.lang.Void>	thenAcceptAsync(Consumer<? super T> action, java.util.concurrent.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> CompletableFuture<java.lang.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> CompletableFuture<java.lang.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> CompletableFuture<java.lang.Void>	thenAcceptBothAsync(CompletionStage<? extends U> other, BiConsumer<? super T,? super U> action, java.util.concurrent.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> CompletableFuture<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> CompletableFuture<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> CompletableFuture<U>	thenApplyAsync(Function<? super T,? extends U> fn, java.util.concurrent.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> CompletableFuture<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> CompletableFuture<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> CompletableFuture<V>	thenCombineAsync(CompletionStage<? extends U> other, BiFunction<? super T,? super U,? extends V> fn, java.util.concurrent.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> CompletableFuture<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> CompletableFuture<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> CompletableFuture<U>	thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn, java.util.concurrent.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.
CompletableFuture<java.lang.Void>	thenRun(java.lang.Runnable action) Returns a new CompletionStage that, when this stage completes normally, executes the given action.
CompletableFuture<java.lang.Void>	thenRunAsync(java.lang.Runnable action) Returns a new CompletionStage that, when this stage completes normally, executes the given action using this stage's default asynchronous execution facility.
CompletableFuture<java.lang.Void>	thenRunAsync(java.lang.Runnable action, java.util.concurrent.Executor executor) Returns a new CompletionStage that, when this stage completes normally, executes the given action using the supplied Executor.
CompletableFuture<T>	toCompletableFuture() Returns this CompletableFuture
java.lang.String	toString() Returns a string identifying this CompletableFuture, as well as its completion state.
CompletableFuture<T>	whenComplete(BiConsumer<? super T,? super java.lang.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.
CompletableFuture<T>	whenCompleteAsync(BiConsumer<? super T,? super java.lang.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.
CompletableFuture<T>	whenCompleteAsync(BiConsumer<? super T,? super java.lang.Throwable> action, java.util.concurrent.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.

Methods inherited from class java.lang.Object

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

Constructor Detail

CompletableFuture

public CompletableFuture()

Creates a new incomplete CompletableFuture.

Method Detail

supplyAsync

public static <U> CompletableFuture<U> supplyAsync(Supplier<U> supplier)

Returns a new CompletableFuture that is asynchronously completed by a task running in the ForkJoinPool.commonPool() with the value obtained by calling the given Supplier.

Type Parameters:

U - the function's return type

Parameters:

supplier - a function returning the value to be used to complete the returned CompletableFuture

Returns:

the new CompletableFuture

supplyAsync

public static <U> CompletableFuture<U> supplyAsync(Supplier<U> supplier,
                                                   java.util.concurrent.Executor executor)

Returns a new CompletableFuture that is asynchronously completed by a task running in the given executor with the value obtained by calling the given Supplier.

Type Parameters:

U - the function's return type

Parameters:

supplier - a function returning the value to be used to complete the returned CompletableFuture

executor - the executor to use for asynchronous execution

Returns:

the new CompletableFuture

runAsync

public static CompletableFuture<java.lang.Void> runAsync(java.lang.Runnable runnable)

Returns a new CompletableFuture that is asynchronously completed by a task running in the ForkJoinPool.commonPool() after it runs the given action.

Parameters:

runnable - the action to run before completing the returned CompletableFuture

Returns:

the new CompletableFuture

runAsync

public static CompletableFuture<java.lang.Void> runAsync(java.lang.Runnable runnable,
                                                         java.util.concurrent.Executor executor)

Returns a new CompletableFuture that is asynchronously completed by a task running in the given executor after it runs the given action.

Parameters:

runnable - the action to run before completing the returned CompletableFuture

executor - the executor to use for asynchronous execution

Returns:

the new CompletableFuture

completedFuture

public static <U> CompletableFuture<U> completedFuture(U value)

Returns a new CompletableFuture that is already completed with the given value.

Type Parameters:

U - the type of the value

Parameters:

value - the value

Returns:

the completed CompletableFuture

isDone

public boolean isDone()

Returns true if completed in any fashion: normally, exceptionally, or via cancellation.

Specified by:

isDone in interface java.util.concurrent.Future<T>

Returns:

true if completed

get

public T get()
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException

Waits if necessary for this future to complete, and then returns its result.

Specified by:

get in interface java.util.concurrent.Future<T>

Returns:

the result value

Throws:

java.util.concurrent.CancellationException - if this future was cancelled

java.util.concurrent.ExecutionException - if this future completed exceptionally

java.lang.InterruptedException - if the current thread was interrupted while waiting

get

public T get(long timeout,
             java.util.concurrent.TimeUnit unit)
      throws java.lang.InterruptedException,
             java.util.concurrent.ExecutionException,
             java.util.concurrent.TimeoutException

Waits if necessary for at most the given time for this future to complete, and then returns its result, if available.

Specified by:

get in interface java.util.concurrent.Future<T>

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

the result value

Throws:

java.util.concurrent.CancellationException - if this future was cancelled

java.util.concurrent.ExecutionException - if this future completed exceptionally

java.lang.InterruptedException - if the current thread was interrupted while waiting

java.util.concurrent.TimeoutException - if the wait timed out

join

public T join()

Returns the result value when complete, or throws an (unchecked) exception if completed exceptionally. To better conform with the use of common functional forms, if a computation involved in the completion of this CompletableFuture threw an exception, this method throws an (unchecked) CompletionException with the underlying exception as its cause.

Returns:

the result value

Throws:

java.util.concurrent.CancellationException - if the computation was cancelled

CompletionException - if this future completed exceptionally or a completion computation threw an exception

getNow

public T getNow(T valueIfAbsent)

Returns the result value (or throws any encountered exception) if completed, else returns the given valueIfAbsent.

Parameters:

valueIfAbsent - the value to return if not completed

Returns:

the result value, if completed, else the given valueIfAbsent

Throws:

java.util.concurrent.CancellationException - if the computation was cancelled

CompletionException - if this future completed exceptionally or a completion computation threw an exception

complete

public boolean complete(T value)

If not already completed, sets the value returned by get() and related methods to the given value.

Parameters:

value - the result value

Returns:

true if this invocation caused this CompletableFuture to transition to a completed state, else false

completeExceptionally

public boolean completeExceptionally(java.lang.Throwable ex)

If not already completed, causes invocations of get() and related methods to throw the given exception.

Parameters:

ex - the exception

Returns:

true if this invocation caused this CompletableFuture to transition to a completed state, else false

thenApply

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

Description copied from interface: CompletionStage

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.

Specified by:

thenApply in interface CompletionStage<T>

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

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

Description copied from interface: CompletionStage

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.

Specified by:

thenApplyAsync in interface CompletionStage<T>

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

public <U> CompletableFuture<U> thenApplyAsync(Function<? super T,? extends U> fn,
                                               java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenApplyAsync in interface CompletionStage<T>

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

public CompletableFuture<java.lang.Void> thenAccept(Consumer<? super T> action)

Description copied from interface: CompletionStage

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.

Specified by:

thenAccept in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptAsync

public CompletableFuture<java.lang.Void> thenAcceptAsync(Consumer<? super T> action)

Description copied from interface: CompletionStage

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.

Specified by:

thenAcceptAsync in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenAcceptAsync

public CompletableFuture<java.lang.Void> thenAcceptAsync(Consumer<? super T> action,
                                                         java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenAcceptAsync in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenRun

public CompletableFuture<java.lang.Void> thenRun(java.lang.Runnable action)

Description copied from interface: CompletionStage

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

Specified by:

thenRun in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenRunAsync

public CompletableFuture<java.lang.Void> thenRunAsync(java.lang.Runnable action)

Description copied from interface: CompletionStage

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.

Specified by:

thenRunAsync in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

thenRunAsync

public CompletableFuture<java.lang.Void> thenRunAsync(java.lang.Runnable action,
                                                      java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenRunAsync in interface CompletionStage<T>

Parameters:

action - the action to perform before completing the returned CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

thenCombine

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

Description copied from interface: CompletionStage

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.

Specified by:

thenCombine in interface CompletionStage<T>

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

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

Description copied from interface: CompletionStage

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.

Specified by:

thenCombineAsync in interface CompletionStage<T>

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

public <U,V> CompletableFuture<V> thenCombineAsync(CompletionStage<? extends U> other,
                                                   BiFunction<? super T,? super U,? extends V> fn,
                                                   java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenCombineAsync in interface CompletionStage<T>

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

public <U> CompletableFuture<java.lang.Void> thenAcceptBoth(CompletionStage<? extends U> other,
                                                            BiConsumer<? super T,? super U> action)

Description copied from interface: CompletionStage

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.

Specified by:

thenAcceptBoth in interface CompletionStage<T>

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

public <U> CompletableFuture<java.lang.Void> thenAcceptBothAsync(CompletionStage<? extends U> other,
                                                                 BiConsumer<? super T,? super U> action)

Description copied from interface: CompletionStage

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.

Specified by:

thenAcceptBothAsync in interface CompletionStage<T>

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

public <U> CompletableFuture<java.lang.Void> thenAcceptBothAsync(CompletionStage<? extends U> other,
                                                                 BiConsumer<? super T,? super U> action,
                                                                 java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenAcceptBothAsync in interface CompletionStage<T>

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

public CompletableFuture<java.lang.Void> runAfterBoth(CompletionStage<?> other,
                                                      java.lang.Runnable action)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterBoth in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterBothAsync

public CompletableFuture<java.lang.Void> runAfterBothAsync(CompletionStage<?> other,
                                                           java.lang.Runnable action)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterBothAsync in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterBothAsync

public CompletableFuture<java.lang.Void> runAfterBothAsync(CompletionStage<?> other,
                                                           java.lang.Runnable action,
                                                           java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterBothAsync in interface CompletionStage<T>

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

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

Description copied from interface: CompletionStage

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.

Specified by:

applyToEither in interface CompletionStage<T>

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

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

Description copied from interface: CompletionStage

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.

Specified by:

applyToEitherAsync in interface CompletionStage<T>

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

public <U> CompletableFuture<U> applyToEitherAsync(CompletionStage<? extends T> other,
                                                   Function<? super T,U> fn,
                                                   java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

applyToEitherAsync in interface CompletionStage<T>

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

public CompletableFuture<java.lang.Void> acceptEither(CompletionStage<? extends T> other,
                                                      Consumer<? super T> action)

Description copied from interface: CompletionStage

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.

Specified by:

acceptEither in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

acceptEitherAsync

public CompletableFuture<java.lang.Void> acceptEitherAsync(CompletionStage<? extends T> other,
                                                           Consumer<? super T> action)

Description copied from interface: CompletionStage

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.

Specified by:

acceptEitherAsync in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

acceptEitherAsync

public CompletableFuture<java.lang.Void> acceptEitherAsync(CompletionStage<? extends T> other,
                                                           Consumer<? super T> action,
                                                           java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

acceptEitherAsync in interface CompletionStage<T>

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

public CompletableFuture<java.lang.Void> runAfterEither(CompletionStage<?> other,
                                                        java.lang.Runnable action)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterEither in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterEitherAsync

public CompletableFuture<java.lang.Void> runAfterEitherAsync(CompletionStage<?> other,
                                                             java.lang.Runnable action)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterEitherAsync in interface CompletionStage<T>

Parameters:

other - the other CompletionStage

action - the action to perform before completing the returned CompletionStage

Returns:

the new CompletionStage

runAfterEitherAsync

public CompletableFuture<java.lang.Void> runAfterEitherAsync(CompletionStage<?> other,
                                                             java.lang.Runnable action,
                                                             java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

runAfterEitherAsync in interface CompletionStage<T>

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

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

Description copied from interface: CompletionStage

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.

Specified by:

thenCompose in interface CompletionStage<T>

Type Parameters:

U - the type of the returned CompletionStage's result

Parameters:

fn - the function returning a new CompletionStage

Returns:

the CompletionStage

thenComposeAsync

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

Description copied from interface: CompletionStage

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.

Specified by:

thenComposeAsync in interface CompletionStage<T>

Type Parameters:

U - the type of the returned CompletionStage's result

Parameters:

fn - the function returning a new CompletionStage

Returns:

the CompletionStage

thenComposeAsync

public <U> CompletableFuture<U> thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn,
                                                 java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

thenComposeAsync in interface CompletionStage<T>

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

whenComplete

public CompletableFuture<T> whenComplete(BiConsumer<? super T,? super java.lang.Throwable> action)

Description copied from interface: CompletionStage

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.

Specified by:

whenComplete in interface CompletionStage<T>

Parameters:

action - the action to perform

Returns:

the new CompletionStage

whenCompleteAsync

public CompletableFuture<T> whenCompleteAsync(BiConsumer<? super T,? super java.lang.Throwable> action)

Description copied from interface: CompletionStage

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.

Specified by:

whenCompleteAsync in interface CompletionStage<T>

Parameters:

action - the action to perform

Returns:

the new CompletionStage

whenCompleteAsync

public CompletableFuture<T> whenCompleteAsync(BiConsumer<? super T,? super java.lang.Throwable> action,
                                              java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

whenCompleteAsync in interface CompletionStage<T>

Parameters:

action - the action to perform

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

handle

public <U> CompletableFuture<U> handle(BiFunction<? super T,java.lang.Throwable,? extends U> fn)

Description copied from interface: CompletionStage

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.

Specified by:

handle in interface CompletionStage<T>

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

public <U> CompletableFuture<U> handleAsync(BiFunction<? super T,java.lang.Throwable,? extends U> fn)

Description copied from interface: CompletionStage

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.

Specified by:

handleAsync in interface CompletionStage<T>

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

public <U> CompletableFuture<U> handleAsync(BiFunction<? super T,java.lang.Throwable,? extends U> fn,
                                            java.util.concurrent.Executor executor)

Description copied from interface: CompletionStage

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.

Specified by:

handleAsync in interface CompletionStage<T>

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

public CompletableFuture<T> toCompletableFuture()

Returns this CompletableFuture

Specified by:

toCompletableFuture in interface CompletionStage<T>

Returns:

this CompletableFuture

exceptionally

public CompletableFuture<T> exceptionally(Function<java.lang.Throwable,? extends T> fn)

Returns a new CompletableFuture that is completed when this CompletableFuture completes, with the result of the given function of the exception triggering this CompletableFuture's completion when it completes exceptionally; otherwise, if this CompletableFuture completes normally, then the returned CompletableFuture also completes normally with the same value. Note: More flexible versions of this functionality are available using methods whenComplete and handle.

Specified by:

exceptionally in interface CompletionStage<T>

Parameters:

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

Returns:

the new CompletableFuture

allOf

public static CompletableFuture<java.lang.Void> allOf(CompletableFuture<?>... cfs)

Returns a new CompletableFuture that is completed when all of the given CompletableFutures complete. If any of the given CompletableFutures complete exceptionally, then the returned CompletableFuture also does so, with a CompletionException holding this exception as its cause. Otherwise, the results, if any, of the given CompletableFutures are not reflected in the returned CompletableFuture, but may be obtained by inspecting them individually. If no CompletableFutures are provided, returns a CompletableFuture completed with the value null.

Among the applications of this method is to await completion of a set of independent CompletableFutures before continuing a program, as in: CompletableFuture.allOf(c1, c2, c3).join();.

Parameters:

cfs - the CompletableFutures

Returns:

a new CompletableFuture that is completed when all of the given CompletableFutures complete

Throws:

java.lang.NullPointerException - if the array or any of its elements are null

anyOf

public static CompletableFuture<java.lang.Object> anyOf(CompletableFuture<?>... cfs)

Returns a new CompletableFuture that is completed when any of the given CompletableFutures complete, with the same result. Otherwise, if it completed exceptionally, the returned CompletableFuture also does so, with a CompletionException holding this exception as its cause. If no CompletableFutures are provided, returns an incomplete CompletableFuture.

Parameters:

cfs - the CompletableFutures

Returns:

a new CompletableFuture that is completed with the result or exception of any of the given CompletableFutures when one completes

Throws:

java.lang.NullPointerException - if the array or any of its elements are null

cancel

public boolean cancel(boolean mayInterruptIfRunning)

If not already completed, completes this CompletableFuture with a CancellationException. Dependent CompletableFutures that have not already completed will also complete exceptionally, with a CompletionException caused by this CancellationException.

Specified by:

cancel in interface java.util.concurrent.Future<T>

Parameters:

mayInterruptIfRunning - this value has no effect in this implementation because interrupts are not used to control processing.

Returns:

true if this task is now cancelled

isCancelled

public boolean isCancelled()

Returns true if this CompletableFuture was cancelled before it completed normally.

Specified by:

isCancelled in interface java.util.concurrent.Future<T>

Returns:

true if this CompletableFuture was cancelled before it completed normally

isCompletedExceptionally

public boolean isCompletedExceptionally()

Returns true if this CompletableFuture completed exceptionally, in any way. Possible causes include cancellation, explicit invocation of completeExceptionally, and abrupt termination of a CompletionStage action.

Returns:

true if this CompletableFuture completed exceptionally

obtrudeValue

public void obtrudeValue(T value)

Forcibly sets or resets the value subsequently returned by method get() and related methods, whether or not already completed. This method is designed for use only in error recovery actions, and even in such situations may result in ongoing dependent completions using established versus overwritten outcomes.

Parameters:

value - the completion value

obtrudeException

public void obtrudeException(java.lang.Throwable ex)

Forcibly causes subsequent invocations of method get() and related methods to throw the given exception, whether or not already completed. This method is designed for use only in recovery actions, and even in such situations may result in ongoing dependent completions using established versus overwritten outcomes.

Parameters:

ex - the exception

getNumberOfDependents

public int getNumberOfDependents()

Returns the estimated number of CompletableFutures whose completions are awaiting completion of this CompletableFuture. This method is designed for use in monitoring system state, not for synchronization control.

Returns:

the number of dependent CompletableFutures

toString

public java.lang.String toString()

Returns a string identifying this CompletableFuture, as well as its completion state. The state, in brackets, contains the String "Completed Normally" or the String "Completed Exceptionally", or the String "Not completed" followed by the number of CompletableFutures dependent upon its completion, if any.

Overrides:

toString in class java.lang.Object

Returns:

a string identifying this CompletableFuture, as well as its state