CompletableFuture (FlexDoc/Javadoc 2.0 Demo)

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 created to run each task). This may be overridden for non-static methods in subclasses by defining method defaultExecutor(). To simplify monitoring, debugging, and tracking, all generated asynchronous tasks are instances of the marker interface CompletableFuture.AsynchronousCompletionTask. Operations with time-delays can use adapter methods defined in this class, for example: supplyAsync(supplier, delayedExecutor(timeout, timeUnit)). To support methods with delays and timeouts, this class maintains at most one daemon thread for triggering and cancelling actions, not for running them.
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.
All CompletionStage methods return CompletableFutures. To restrict usages to only those methods defined in interface CompletionStage, use method minimalCompletionStage(). Or to ensure only that clients do not themselves modify a future, use method copy().

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.

Arguments used to pass a completion result (that is, for parameters of type T) for methods accepting them may be null, but passing a null value for any other parameter will result in a NullPointerException being thrown.

Subclasses of this class should normally override the "virtual constructor" method newIncompleteFuture(), which establishes the concrete type returned by CompletionStage methods. For example, here is a class that substitutes a different default Executor and disables the obtrude methods:

 
 class MyCompletableFuture<T> extends CompletableFuture<T> {
   static final Executor myExecutor = ...;
   public MyCompletableFuture() { }
   public <U> CompletableFuture<U> newIncompleteFuture() {
     return new MyCompletableFuture<U>(); }
   public Executor defaultExecutor() {
     return myExecutor; }
   public void obtrudeValue(T value) {
     throw new UnsupportedOperationException(); }
   public void obtrudeException(Throwable ex) {
     throw new UnsupportedOperationException(); }
 }

Since:

1.8

Author:

Doug Lea

Nested Class Summary
static interface	CompletableFuture.AsynchronousCompletionTask A marker interface identifying asynchronous tasks produced by async methods.

Constructor Summary
CompletableFuture() Creates a new incomplete CompletableFuture.

Method Summary
CompletableFuture<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<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<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 action.
static CompletableFuture<Void>	allOf(CompletableFuture<?>... cfs) Returns a new CompletableFuture that is completed when all of the given CompletableFutures complete.
static CompletableFuture<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, 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.
CompletableFuture<T>	completeAsync(Supplier<? extends T> supplier) Completes this CompletableFuture with the result of the given Supplier function invoked from an asynchronous task using the default executor.
CompletableFuture<T>	completeAsync(Supplier<? extends T> supplier, Executor executor) Completes this CompletableFuture with the result of the given Supplier function invoked from an asynchronous task using the given executor.
static <U> CompletableFuture<U>	completedFuture(U value) Returns a new CompletableFuture that is already completed with the given value.
static <U> CompletionStage<U>	completedStage(U value) Returns a new CompletionStage that is already completed with the given value and supports only those methods in interface CompletionStage.
boolean	completeExceptionally(Throwable ex) If not already completed, causes invocations of get() and related methods to throw the given exception.
CompletableFuture<T>	completeOnTimeout(T value, long timeout, TimeUnit unit) Completes this CompletableFuture with the given value if not otherwise completed before the given timeout.
CompletableFuture<T>	copy() Returns a new CompletableFuture that is completed normally with the same value as this CompletableFuture when it completes normally.
Executor	defaultExecutor() Returns the default Executor used for async methods that do not specify an Executor.
static Executor	delayedExecutor(long delay, TimeUnit unit) Returns a new Executor that submits a task to the default executor after the given delay (or no delay if non-positive).
static Executor	delayedExecutor(long delay, TimeUnit unit, Executor executor) Returns a new Executor that submits a task to the given base executor after the given delay (or no delay if non-positive).
CompletableFuture<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.
CompletableFuture<T>	exceptionallyAsync(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, using this stage's default asynchronous execution facility.
CompletableFuture<T>	exceptionallyAsync(Function<Throwable,? extends T> fn, Executor executor) Returns a new CompletionStage that, when this stage completes exceptionally, is executed with this stage's exception as the argument to the supplied function, using the supplied Executor.
CompletableFuture<T>	exceptionallyCompose(Function<Throwable,? extends CompletionStage<T>> fn) Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception.
CompletableFuture<T>	exceptionallyComposeAsync(Function<Throwable,? extends CompletionStage<T>> fn) Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception, using this stage's default asynchronous execution facility.
CompletableFuture<T>	exceptionallyComposeAsync(Function<Throwable,? extends CompletionStage<T>> fn, Executor executor) Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception, using the supplied Executor.
static <U> CompletableFuture<U>	failedFuture(Throwable ex) Returns a new CompletableFuture that is already completed exceptionally with the given exception.
static <U> CompletionStage<U>	failedStage(Throwable ex) Returns a new CompletionStage that is already completed exceptionally with the given exception and supports only those methods in interface CompletionStage.
T	get() Waits if necessary for this future to complete, and then returns its result.
T	get(long timeout, 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,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,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,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.
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.
CompletionStage<T>	minimalCompletionStage() Returns a new CompletionStage that is completed normally with the same value as this CompletableFuture when it completes normally, and cannot be independently completed or otherwise used in ways not defined by the methods of interface CompletionStage.
<U> CompletableFuture<U>	newIncompleteFuture() Returns a new incomplete CompletableFuture of the type to be returned by a CompletionStage method.
void	obtrudeException(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<T>	orTimeout(long timeout, TimeUnit unit) Exceptionally completes this CompletableFuture with a TimeoutException if not otherwise completed before the given timeout.
CompletableFuture<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.
CompletableFuture<Void>	runAfterBothAsync(CompletionStage<?> other, Runnable action) Returns a new CompletionStage that, when this and the other given stage both complete normally, executes the given action using this stage's default asynchronous execution facility.
CompletableFuture<Void>	runAfterBothAsync(CompletionStage<?> other, Runnable action, Executor executor) Returns a new CompletionStage that, when this and the other given stage both complete normally, executes the given action using the supplied executor.
CompletableFuture<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.
CompletableFuture<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.
CompletableFuture<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 the supplied executor.
static CompletableFuture<Void>	runAsync(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<Void>	runAsync(Runnable runnable, 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, 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<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<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<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> CompletableFuture<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<Void>	thenAcceptBothAsync(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 using this stage's default asynchronous execution facility, with the two results as arguments to the supplied action.
<U> CompletableFuture<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 both complete normally, is executed using the supplied executor, with the two results as arguments to the supplied action.
<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, 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 both 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, Executor executor) Returns a new CompletionStage that, when this and the other given stage both 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 is completed with the same value as the CompletionStage returned by the given function.
<U> CompletableFuture<U>	thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn) Returns a new CompletionStage that is completed with the same value as the CompletionStage returned by the given function, executed using this stage's default asynchronous execution facility.
<U> CompletableFuture<U>	thenComposeAsync(Function<? super T,? extends CompletionStage<U>> fn, Executor executor) Returns a new CompletionStage that is completed with the same value as the CompletionStage returned by the given function, executed using the supplied Executor.
CompletableFuture<Void>	thenRun(Runnable action) Returns a new CompletionStage that, when this stage completes normally, executes the given action.
CompletableFuture<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.
CompletableFuture<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 this CompletableFuture.
String	toString() Returns a string identifying this CompletableFuture, as well as its completion state.
CompletableFuture<T>	whenComplete(BiConsumer<? super T,? super Throwable> action) Returns a new CompletionStage with the same result or exception as this stage, that executes the given action when this stage completes.
CompletableFuture<T>	whenCompleteAsync(BiConsumer<? super T,? super Throwable> action) Returns a new CompletionStage with the same result or exception as this stage, that executes the given action using this stage's default asynchronous execution facility when this stage completes.
CompletableFuture<T>	whenCompleteAsync(BiConsumer<? super T,? super Throwable> action, Executor executor) Returns a new CompletionStage with the same result or exception as this stage, that executes the given action using the supplied Executor when this stage completes.

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 CompletableFuture supplyAsync

(Supplier 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 CompletableFuture supplyAsync

(Supplier supplier,
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<Void> runAsync

(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<Void> runAsync

(Runnable runnable,
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 CompletableFuture 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 Future<T>

Returns:

true if completed

get

public T get	()
throws	InterruptedException, ExecutionException

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

Specified by:

get in interface Future<T>

Returns:

the result value

Throws:

CancellationException - if this future was cancelled

ExecutionException - if this future completed exceptionally

InterruptedException - if the current thread was interrupted while waiting

get

public T get	(long timeout, TimeUnit unit)
throws	InterruptedException, ExecutionException, 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 Future<T>

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

the result value

Throws:

CancellationException - if this future was cancelled

ExecutionException - if this future completed exceptionally

InterruptedException - if the current thread was interrupted while waiting

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:

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:

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

(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 CompletableFuture 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.

This method is analogous to Optional.map and Stream.map.

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 CompletableFuture 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 CompletableFuture thenApplyAsync

(Function<? super T,? extends U> fn,
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<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<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<Void> thenAcceptAsync

(Consumer<? super T> action,
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<Void> thenRun

(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<Void> thenRunAsync

(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<Void> thenRunAsync

(Runnable action,
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 both 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,
Executor executor)

Description copied from interface: CompletionStage

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

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 CompletableFuture<Void> thenAcceptBothAsync

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

Description copied from interface: CompletionStage

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

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<Void> runAfterBoth

(CompletionStage<?> other,
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<Void> runAfterBothAsync

(CompletionStage<?> other,
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 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<Void> runAfterBothAsync

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that, when this and the other given stage both 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 CompletableFuture 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 CompletableFuture 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 CompletableFuture applyToEitherAsync

(CompletionStage<? extends T> other,
Function<? super T,U> fn,
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<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<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<Void> acceptEitherAsync

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

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

runAfterEither

public CompletableFuture<Void> runAfterEither

(CompletionStage<?> other,
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<Void> runAfterEitherAsync

(CompletionStage<?> other,
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<Void> runAfterEitherAsync

(CompletionStage<?> other,
Runnable action,
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 the 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 CompletableFuture thenCompose

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that is completed with the same value as the CompletionStage returned by the given function.

When this stage completes normally, the given function is invoked with this stage's result as the argument, returning another CompletionStage. When that stage completes normally, the CompletionStage returned by this method is completed with the same value.

To ensure progress, the supplied function must arrange eventual completion of its result.

This method is analogous to Optional.flatMap and Stream.flatMap.

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 to use to compute another CompletionStage

Returns:

the new CompletionStage

thenComposeAsync

public CompletableFuture thenComposeAsync

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that is completed with the same value as the CompletionStage returned by the given function, executed using this stage's default asynchronous execution facility.

To ensure progress, the supplied function must arrange eventual completion of its result.

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 to use to compute another CompletionStage

Returns:

the new CompletionStage

thenComposeAsync

public CompletableFuture thenComposeAsync

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that is completed with the same value as the CompletionStage returned by the given function, executed using the supplied Executor.

To ensure progress, the supplied function must arrange eventual completion of its result.

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 to use to compute another CompletionStage

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

whenComplete

public CompletableFuture<T> whenComplete

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

Description copied from interface: CompletionStage

Returns a new CompletionStage with the same result or exception as this stage, that executes the given action when this stage completes.

When this stage is complete, the given action is invoked with the result (or null if none) and the exception (or null if none) of this stage as arguments. The returned stage is completed when the action returns.

Unlike method handle, this method is not designed to translate completion outcomes, so the supplied action should not throw an exception. However, if it does, the following rules apply: if this stage completed normally but the supplied action throws an exception, then the returned stage completes exceptionally with the supplied action's exception. Or, if this stage completed exceptionally and the supplied action throws an exception, then the returned stage completes exceptionally with this stage's exception.

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 Throwable> action)

Description copied from interface: CompletionStage

Returns a new CompletionStage with the same result or exception as this stage, that executes the given action using this stage's default asynchronous execution facility when this stage completes.

Unlike method handleAsync, this method is not designed to translate completion outcomes, so the supplied action should not throw an exception. However, if it does, the following rules apply: If this stage completed normally but the supplied action throws an exception, then the returned stage completes exceptionally with the supplied action's exception. Or, if this stage completed exceptionally and the supplied action throws an exception, then the returned stage completes exceptionally with this stage's exception.

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 Throwable> action,
Executor executor)

Description copied from interface: CompletionStage

Returns a new CompletionStage with the same result or exception as this stage, that executes the given action using the supplied Executor when this stage completes.

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 CompletableFuture handle

(BiFunction<? super T,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.

When this stage is complete, the given function is invoked with the result (or null if none) and the exception (or null if none) of this stage as arguments, and the function's result is used to complete the returned stage.

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 CompletableFuture handleAsync

(BiFunction<? super T,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.

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 CompletableFuture handleAsync

(BiFunction<? super T,Throwable,? extends U> fn,
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.

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<Throwable,? extends T> fn)

Description copied from interface: CompletionStage

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.

Specified by:

exceptionally in interface CompletionStage<T>

Parameters:

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

Returns:

the new CompletionStage

exceptionallyAsync

public CompletableFuture<T> exceptionallyAsync

(Function<Throwable,? extends T> fn)

Description copied from interface: CompletionStage

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

Specified by:

exceptionallyAsync in interface CompletionStage<T>

Parameters:

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

Returns:

the new CompletionStage

exceptionallyAsync

public CompletableFuture<T> exceptionallyAsync

(Function<Throwable,? extends T> fn,
Executor executor)

Description copied from interface: CompletionStage

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

Specified by:

exceptionallyAsync in interface CompletionStage<T>

Parameters:

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

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

exceptionallyCompose

public CompletableFuture<T> exceptionallyCompose

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception.

Specified by:

exceptionallyCompose in interface CompletionStage<T>

Parameters:

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

Returns:

the new CompletionStage

exceptionallyComposeAsync

public CompletableFuture<T> exceptionallyComposeAsync

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception, using this stage's default asynchronous execution facility.

Specified by:

exceptionallyComposeAsync in interface CompletionStage<T>

Parameters:

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

Returns:

the new CompletionStage

exceptionallyComposeAsync

public CompletableFuture<T> exceptionallyComposeAsync

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

Description copied from interface: CompletionStage

Returns a new CompletionStage that, when this stage completes exceptionally, is composed using the results of the supplied function applied to this stage's exception, using the supplied Executor.

Specified by:

exceptionallyComposeAsync in interface CompletionStage<T>

Parameters:

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

executor - the executor to use for asynchronous execution

Returns:

the new CompletionStage

allOf

public static CompletableFuture<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:

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

anyOf

public static CompletableFuture<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:

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 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 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

(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 error recovery actions, and even in such situations may result in ongoing dependent completions using established versus overwritten outcomes.

Parameters:

ex - the exception

Throws:

NullPointerException - if the exception is null

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 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 Object

Returns:

a string identifying this CompletableFuture, as well as its state

newIncompleteFuture

public CompletableFuture newIncompleteFuture

()

Returns a new incomplete CompletableFuture of the type to be returned by a CompletionStage method. Subclasses should normally override this method to return an instance of the same class as this CompletableFuture. The default implementation returns an instance of class CompletableFuture.

Type Parameters:

U - the type of the value

Returns:

a new CompletableFuture

Since:

defaultExecutor

public Executor defaultExecutor

()

Returns the default Executor used for async methods that do not specify an Executor. This class uses the ForkJoinPool.commonPool() if it supports more than one parallel thread, or else an Executor using one thread per async task. This method may be overridden in subclasses to return an Executor that provides at least one independent thread.

Returns:

the executor

Since:

copy

public CompletableFuture<T> copy

()

Returns a new CompletableFuture that is completed normally with the same value as this CompletableFuture when it completes normally. If this CompletableFuture completes exceptionally, then the returned CompletableFuture completes exceptionally with a CompletionException with this exception as cause. The behavior is equivalent to thenApply(x -> x). This method may be useful as a form of "defensive copying", to prevent clients from completing, while still being able to arrange dependent actions.

Returns:

the new CompletableFuture

Since:

minimalCompletionStage

public CompletionStage<T> minimalCompletionStage

()

Returns a new CompletionStage that is completed normally with the same value as this CompletableFuture when it completes normally, and cannot be independently completed or otherwise used in ways not defined by the methods of interface CompletionStage. If this CompletableFuture completes exceptionally, then the returned CompletionStage completes exceptionally with a CompletionException with this exception as cause.

Unless overridden by a subclass, a new non-minimal CompletableFuture with all methods available can be obtained from a minimal CompletionStage via toCompletableFuture(). For example, completion of a minimal stage can be awaited by

 minimalStage.toCompletableFuture().join();

Returns:

the new CompletionStage

Since:

completeAsync

public CompletableFuture<T> completeAsync

(Supplier<? extends T> supplier,
Executor executor)

Completes this CompletableFuture with the result of the given Supplier function invoked from an asynchronous task using the given executor.

Parameters:

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

executor - the executor to use for asynchronous execution

Returns:

this CompletableFuture

Since:

completeAsync

public CompletableFuture<T> completeAsync

(Supplier<? extends T> supplier)

Completes this CompletableFuture with the result of the given Supplier function invoked from an asynchronous task using the default executor.

Parameters:

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

Returns:

this CompletableFuture

Since:

orTimeout

public CompletableFuture<T> orTimeout

(long timeout,
TimeUnit unit)

Exceptionally completes this CompletableFuture with a TimeoutException if not otherwise completed before the given timeout.

Parameters:

timeout - how long to wait before completing exceptionally with a TimeoutException, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

Returns:

this CompletableFuture

Since:

completeOnTimeout

public CompletableFuture<T> completeOnTimeout

(T value,
long timeout,
TimeUnit unit)

Completes this CompletableFuture with the given value if not otherwise completed before the given timeout.

Parameters:

value - the value to use upon timeout

timeout - how long to wait before completing normally with the given value, in units of unit

unit - a TimeUnit determining how to interpret the timeout parameter

Returns:

this CompletableFuture

Since:

delayedExecutor

public static Executor delayedExecutor

(long delay,
TimeUnit unit,
Executor executor)

Returns a new Executor that submits a task to the given base executor after the given delay (or no delay if non-positive). Each delay commences upon invocation of the returned executor's execute method.

Parameters:

delay - how long to delay, in units of unit

unit - a TimeUnit determining how to interpret the delay parameter

executor - the base executor

Returns:

the new delayed executor

Since:

delayedExecutor

public static Executor delayedExecutor

(long delay,
TimeUnit unit)

Returns a new Executor that submits a task to the default executor after the given delay (or no delay if non-positive). Each delay commences upon invocation of the returned executor's execute method.

Parameters:

delay - how long to delay, in units of unit

unit - a TimeUnit determining how to interpret the delay parameter

Returns:

the new delayed executor

Since:

completedStage

public static CompletionStage completedStage

(U value)

Returns a new CompletionStage that is already completed with the given value and supports only those methods in interface CompletionStage.

Type Parameters:

U - the type of the value

Parameters:

value - the value

Returns:

the completed CompletionStage

Since:

failedFuture

public static CompletableFuture failedFuture

(Throwable ex)

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

Type Parameters:

U - the type of the value

Parameters:

ex - the exception

Returns:

the exceptionally completed CompletableFuture

Since:

failedStage

public static CompletionStage failedStage

(Throwable ex)

Returns a new CompletionStage that is already completed exceptionally with the given exception and supports only those methods in interface CompletionStage.

Type Parameters:

U - the type of the value

Parameters:

ex - the exception

Returns:

the exceptionally completed CompletionStage

Since:

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