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Object scala.concurrent.Future

Companion trait Future

object Future

Future companion object.

Source
Future.scala
Linear Supertypes
AnyRef, Any

Value Members

final def !=(arg0: Any): Boolean

Test two objects for inequality.

returns

true if !(this == that), false otherwise.

Definition Classes
AnyRef → Any

final def ##(): Int

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

returns

a hash value consistent with ==

Definition Classes
AnyRef → Any

final def ==(arg0: Any): Boolean

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

returns

true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
AnyRef → Any

final def apply[T](body: => T)(implicit executor: ExecutionContext): Future[T]

Starts an asynchronous computation and returns a Future instance with the result of that computation.

The following expressions are equivalent:

val f1 = Future(expr)
val f2 = Future.unit.map(_ => expr)
val f3 = Future.unit.transform(_ => Success(expr))

The result becomes available once the asynchronous computation is completed.

T

the type of the result

body

the asynchronous computation

executor

the execution context on which the future is run

returns

the Future holding the result of the computation

final def asInstanceOf[T0]: T0

Cast the receiver object to be of type T0.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

returns

the receiver object.

Definition Classes
Any
Exceptions thrown

ClassCastException if the receiver object is not an instance of the erasure of type T0.

def clone(): AnyRef

Create a copy of the receiver object.

The default implementation of the clone method is platform dependent.

returns

a copy of the receiver object.

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
Note

not specified by SLS as a member of AnyRef

final def delegate[T](body: => Future[T])(implicit executor: ExecutionContext): Future[T]

Starts an asynchronous computation and returns a Future instance with the result of that computation once it completes.

The following expressions are semantically equivalent:

val f1 = Future(expr).flatten
val f2 = Future.delegate(expr)
val f3 = Future.unit.flatMap(_ => expr)

The result becomes available once the resulting Future of the asynchronous computation is completed.

T

the type of the result

body

the asynchronous computation, returning a Future

executor

the execution context on which the body is evaluated in

returns

the Future holding the result of the computation

final def eq(arg0: AnyRef): Boolean

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

    It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false. null.eq(null) returns true.

When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

returns

true if the argument is a reference to the receiver object; false otherwise.

Definition Classes
AnyRef

def equals(arg0: AnyRef): Boolean

The equality method for reference types. Default implementation delegates to eq.

See also equals in scala.Any.

returns

true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes
AnyRef → Any

final def failed[T](exception: Throwable): Future[T]

Creates an already completed Future with the specified exception.

T

the type of the value in the future

exception

the non-null instance of Throwable

returns

the newly created Future instance

def finalize(): Unit

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
Note

not specified by SLS as a member of AnyRef

final def find[T](futures: collection.immutable.Iterable[Future[T]])(p: (T) => Boolean)(implicit executor: ExecutionContext): Future[Option[T]]

Asynchronously and non-blockingly returns a Future that will hold the optional result of the first Future with a result that matches the predicate, failed Futures will be ignored.

T

the type of the value in the future

futures

the scala.collection.immutable.Iterable of Futures to search

p

the predicate which indicates if it's a match

returns

the Future holding the optional result of the search

final def firstCompletedOf[T](futures: IterableOnce[Future[T]])(implicit executor: ExecutionContext): Future[T]

Asynchronously and non-blockingly returns a new Future to the result of the first future in the list that is completed. This means no matter if it is completed as a success or as a failure.

T

the type of the value in the future

futures

the IterableOnce of Futures in which to find the first completed

returns

the Future holding the result of the future that is first to be completed

final def foldLeft[T, R](futures: collection.immutable.Iterable[Future[T]])(zero: R)(op: (R, T) => R)(implicit executor: ExecutionContext): Future[R]

A non-blocking, asynchronous left fold over the specified futures, with the start value of the given zero. The fold is performed asynchronously in left-to-right order as the futures become completed. The result will be the first failure of any of the futures, or any failure in the actual fold, or the result of the fold.

Example:

val futureSum = Future.foldLeft(futures)(0)(_ + _)
T

the type of the value of the input Futures

R

the type of the value of the returned Future

futures

the scala.collection.immutable.Iterable of Futures to be folded

zero

the start value of the fold

op

the fold operation to be applied to the zero and futures

returns

the Future holding the result of the fold

final def fromTry[T](result: Try[T]): Future[T]

Creates an already completed Future with the specified result or exception.

T

the type of the value in the Future

result

the result of the returned Future instance

returns

the newly created Future instance

final def getClass(): Class[_ <: AnyRef]

Returns the runtime class representation of the object.

returns

a class object corresponding to the runtime type of the receiver.

Definition Classes
AnyRef → Any
Annotations
@native()

def hashCode(): Int

The hashCode method for reference types. See hashCode in scala.Any.

returns

the hash code value for this object.

Definition Classes
AnyRef → Any
Annotations
@native()

final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is T0.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

returns

true if the receiver object is an instance of erasure of type T0; false otherwise.

Definition Classes
Any

final def ne(arg0: AnyRef): Boolean

Equivalent to !(this eq that).

returns

true if the argument is not a reference to the receiver object; false otherwise.

Definition Classes
AnyRef

final def notify(): Unit

Wakes up a single thread that is waiting on the receiver object's monitor.

Definition Classes
AnyRef
Annotations
@native()
Note

not specified by SLS as a member of AnyRef

final def notifyAll(): Unit

Wakes up all threads that are waiting on the receiver object's monitor.

Definition Classes
AnyRef
Annotations
@native()
Note

not specified by SLS as a member of AnyRef

final def reduceLeft[T, R >: T](futures: collection.immutable.Iterable[Future[T]])(op: (R, T) => R)(implicit executor: ExecutionContext): Future[R]

Initiates a non-blocking, asynchronous, left reduction over the supplied futures where the zero is the result value of the first Future.

Example:

val futureSum = Future.reduceLeft(futures)(_ + _)
T

the type of the value of the input Futures

R

the type of the value of the returned Future

futures

the scala.collection.immutable.Iterable of Futures to be reduced

op

the reduce operation which is applied to the results of the futures

returns

the Future holding the result of the reduce

final def sequence[A, CC[X] <: IterableOnce[X], To](in: CC[Future[A]])(implicit bf: BuildFrom[CC[Future[A]], A, To], executor: ExecutionContext): Future[To]

Simple version of Future.traverse. Asynchronously and non-blockingly transforms, in essence, a IterableOnce[Future[A]] into a Future[IterableOnce[A]]. Useful for reducing many Futures into a single Future.

A

the type of the value inside the Futures

CC

the type of the IterableOnce of Futures

To

the type of the resulting collection

in

the IterableOnce of Futures which will be sequenced

returns

the Future of the resulting collection

final def successful[T](result: T): Future[T]

Creates an already completed Future with the specified result.

T

the type of the value in the future

result

the given successful value

returns

the newly created Future instance

final def synchronized[T0](arg0: => T0): T0

Definition Classes
AnyRef

def toString(): String

Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

returns

a String representation of the object.

Definition Classes
AnyRef → Any

final def traverse[A, B, M[X] <: IterableOnce[X]](in: M[A])(fn: (A) => Future[B])(implicit bf: BuildFrom[M[A], B, M[B]], executor: ExecutionContext): Future[M[B]]

Asynchronously and non-blockingly transforms a IterableOnce[A] into a Future[IterableOnce[B]] using the provided function A => Future[B]. This is useful for performing a parallel map. For example, to apply a function to all items of a list in parallel:

val myFutureList = Future.traverse(myList)(x => Future(myFunc(x)))
A

the type of the value inside the Futures in the collection

B

the type of the value of the returned Future

M

the type of the collection of Futures

in

the collection to be mapped over with the provided function to produce a collection of Futures that is then sequenced into a Future collection

fn

the function to be mapped over the collection to produce a collection of Futures

returns

the Future of the collection of results

final val unit: Future[Unit]

final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])

final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])

final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

object never extends Future[Nothing]

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.13.0/scala/concurrent/Future$.html