object Future
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final
def
!=(arg0: Any): Boolean
Test two objects for inequality.
Test two objects for inequality.
- returns
trueif !(this == that), false otherwise.
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
Equivalent to
x.hashCodeexcept for boxed numeric types andnull.Equivalent to
x.hashCodeexcept for boxed numeric types andnull. 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. Fornullreturns a hashcode wherenull.hashCodethrows aNullPointerException.- returns
a hash value consistent with ==
- Definition Classes
- AnyRef → Any
-
final
def
==(arg0: Any): Boolean
The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).The expression
x == thatis equivalent toif (x eq null) that eq null else x.equals(that).- returns
trueif the receiver object is equivalent to the argument;falseotherwise.
- Definition Classes
- AnyRef → Any
-
def
apply[T](body: ⇒ T)(implicit executor: ExecutionContext): Future[T]
Starts an asynchronous computation and returns a
Futureinstance with the result of that computation.Starts an asynchronous computation and returns a
Futureinstance with the result of that computation.The following expressions are equivalent:
val f1 = Future(expr) val f2 = Future.unit.map(_ => 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
Futureholding the result of the computation
-
final
def
asInstanceOf[T0]: T0
Cast the receiver object to be of type
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 aClassCastExceptionat runtime, while the expressionList(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
ClassCastExceptionif the receiver object is not an instance of the erasure of typeT0.
-
def
clone(): AnyRef
Create a copy of the receiver object.
-
final
def
eq(arg0: AnyRef): Boolean
Tests whether the argument (
that) is a reference to the receiver object (this).Tests whether the argument (
that) is a reference to the receiver object (this).The
eqmethod implements an equivalence relation on non-null instances ofAnyRef, and has three additional properties:- It is consistent: for any non-null instances
xandyof typeAnyRef, multiple invocations ofx.eq(y)consistently returnstrueor consistently returnsfalse. - For any non-null instance
xof typeAnyRef,x.eq(null)andnull.eq(x)returnsfalse. null.eq(null)returnstrue.
When overriding the
equalsorhashCodemethods, 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
trueif the argument is a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
- It is consistent: for any non-null instances
-
def
equals(arg0: Any): Boolean
The equality method for reference types.
-
def
failed[T](exception: Throwable): Future[T]
Creates an already completed Future with the specified exception.
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
Futureinstance
-
def
finalize(): Unit
Called by the garbage collector on the receiver object when there are no more references to the object.
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
finalizemethod is invoked, as well as the interaction betweenfinalizeand non-local returns and exceptions, are all platform dependent.- Attributes
- protected[lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
- Note
not specified by SLS as a member of AnyRef
-
def
find[T](futures: collection.immutable.Iterable[Future[T]])(p: (T) ⇒ Boolean)(implicit executor: ExecutionContext): Future[Option[T]]
Asynchronously and non-blockingly returns a
Futurethat will hold the optional result of the firstFuturewith a result that matches the predicate, failedFutures will be ignored.Asynchronously and non-blockingly returns a
Futurethat will hold the optional result of the firstFuturewith a result that matches the predicate, failedFutures will be ignored.- T
the type of the value in the future
- futures
the
scala.collection.immutable.Iterableof Futures to search- p
the predicate which indicates if it's a match
- returns
the
Futureholding the optional result of the search
-
def
firstCompletedOf[T](futures: TraversableOnce[Future[T]])(implicit executor: ExecutionContext): Future[T]
Asynchronously and non-blockingly returns a new
Futureto the result of the first future in the list that is completed.Asynchronously and non-blockingly returns a new
Futureto 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
TraversableOnceof Futures in which to find the first completed- returns
the
Futureholding the result of the future that is first to be completed
-
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.
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.Iterableof 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
Futureholding the result of the fold
-
def
fromTry[T](result: Try[T]): Future[T]
Creates an already completed Future with the specified result or exception.
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
Futureinstance- returns
the newly created
Futureinstance
-
final
def
getClass(): Class[_]
Returns the runtime class representation of the object.
-
def
hashCode(): Int
The hashCode method for reference types.
-
final
def
isInstanceOf[T0]: Boolean
Test whether the dynamic type of the receiver object is
T0.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 returnfalse, while the expressionList(1).isInstanceOf[List[String]]will returntrue. 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
trueif the receiver object is an instance of erasure of typeT0;falseotherwise.
- Definition Classes
- Any
-
final
def
ne(arg0: AnyRef): Boolean
Equivalent to
!(this eq that).Equivalent to
!(this eq that).- returns
trueif the argument is not a reference to the receiver object;falseotherwise.
- Definition Classes
- AnyRef
-
final
def
notify(): Unit
Wakes up a single thread that is waiting on the receiver object's monitor.
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.
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
-
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.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.Iterableof Futures to be reduced- op
the reduce operation which is applied to the results of the futures
- returns
the
Futureholding the result of the reduce
-
def
sequence[A, M[X] <: TraversableOnce[X]](in: M[Future[A]])(implicit cbf: CanBuildFrom[M[Future[A]], A, M[A]], executor: ExecutionContext): Future[M[A]]
Simple version of
Future.traverse.Simple version of
Future.traverse. Asynchronously and non-blockingly transforms aTraversableOnce[Future[A]]into aFuture[TraversableOnce[A]]. Useful for reducing manyFutures into a singleFuture.- A
the type of the value inside the Futures
- M
the type of the
TraversableOnceof Futures- in
the
TraversableOnceof Futures which will be sequenced- returns
the
Futureof theTraversableOnceof results
-
def
successful[T](result: T): Future[T]
Creates an already completed Future with the specified result.
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
Futureinstance
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
Creates a String representation of this object.
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
-
def
traverse[A, B, M[X] <: TraversableOnce[X]](in: M[A])(fn: (A) ⇒ Future[B])(implicit cbf: CanBuildFrom[M[A], B, M[B]], executor: ExecutionContext): Future[M[B]]
Asynchronously and non-blockingly transforms a
TraversableOnce[A]into aFuture[TraversableOnce[B]]using the provided functionA => Future[B].Asynchronously and non-blockingly transforms a
TraversableOnce[A]into aFuture[TraversableOnce[B]]using the provided functionA => 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
TraversableOnce- B
the type of the value of the returned
Future- M
the type of the
TraversableOnceof Futures- in
the
TraversableOnceof Futures which will be sequenced- fn
the function to apply to the
TraversableOnceof Futures to produce the results- returns
the
Futureof theTraversableOnceof results
-
val
unit: Future[Unit]
A Future which is always completed with the Unit value.
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- final def wait(arg0: Long): Unit
-
object
never extends Future[Nothing]
A Future which is never completed.
Deprecated Value Members
-
def
find[T](futures: TraversableOnce[Future[T]])(p: (T) ⇒ Boolean)(implicit executor: ExecutionContext): Future[Option[T]]
Asynchronously and non-blockingly returns a
Futurethat will hold the optional result of the firstFuturewith a result that matches the predicate.Asynchronously and non-blockingly returns a
Futurethat will hold the optional result of the firstFuturewith a result that matches the predicate.- T
the type of the value in the future
- futures
the
TraversableOnceof Futures to search- p
the predicate which indicates if it's a match
- returns
the
Futureholding the optional result of the search
- Annotations
- @deprecated
- Deprecated
(Since version 2.12.0) use the overloaded version of this method that takes a scala.collection.immutable.Iterable instead
-
def
fold[T, R](futures: TraversableOnce[Future[T]])(zero: R)(op: (R, T) ⇒ R)(implicit executor: ExecutionContext): Future[R]
A non-blocking, asynchronous fold over the specified futures, with the start value of the given zero.
A non-blocking, asynchronous fold over the specified futures, with the start value of the given zero. The fold is performed on the thread where the last future is 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.fold(futures)(0)(_ + _)
- T
the type of the value of the input Futures
- R
the type of the value of the returned
Future- futures
the
TraversableOnceof 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
Futureholding the result of the fold
- Annotations
- @deprecated
- Deprecated
(Since version 2.12.0) use Future.foldLeft instead
-
def
reduce[T, R >: T](futures: TraversableOnce[Future[T]])(op: (R, T) ⇒ R)(implicit executor: ExecutionContext): Future[R]
Initiates a non-blocking, asynchronous, fold over the supplied futures where the fold-zero is the result value of the first
Futurein the collection.Initiates a non-blocking, asynchronous, fold over the supplied futures where the fold-zero is the result value of the first
Futurein the collection.Example:
val futureSum = Future.reduce(futures)(_ + _)- T
the type of the value of the input Futures
- R
the type of the value of the returned
Future- futures
the
TraversableOnceof Futures to be reduced- op
the reduce operation which is applied to the results of the futures
- returns
the
Futureholding the result of the reduce
- Annotations
- @deprecated
- Deprecated
(Since version 2.12.0) use Future.reduceLeft instead
This is the documentation for the Scala standard library.
Package structure
The scala package contains core types like
Int,Float,ArrayorOptionwhich are accessible in all Scala compilation units without explicit qualification or imports.Notable packages include:
scala.collectionand its sub-packages contain Scala's collections frameworkscala.collection.immutable- Immutable, sequential data-structures such asVector,List,Range,HashMaporHashSetscala.collection.mutable- Mutable, sequential data-structures such asArrayBuffer,StringBuilder,HashMaporHashSetscala.collection.concurrent- Mutable, concurrent data-structures such asTrieMapscala.collection.parallel.immutable- Immutable, parallel data-structures such asParVector,ParRange,ParHashMaporParHashSetscala.collection.parallel.mutable- Mutable, parallel data-structures such asParArray,ParHashMap,ParTrieMaporParHashSetscala.concurrent- Primitives for concurrent programming such asFuturesandPromisesscala.io- Input and output operationsscala.math- Basic math functions and additional numeric types likeBigIntandBigDecimalscala.sys- Interaction with other processes and the operating systemscala.util.matching- Regular expressionsOther packages exist. See the complete list on the right.
Additional parts of the standard library are shipped as separate libraries. These include:
scala.reflect- Scala's reflection API (scala-reflect.jar)scala.xml- XML parsing, manipulation, and serialization (scala-xml.jar)scala.swing- A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)scala.util.parsing- Parser combinators (scala-parser-combinators.jar)Automatic imports
Identifiers in the scala package and the
scala.Predefobject are always in scope by default.Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example,
Listis an alias forscala.collection.immutable.List.Other aliases refer to classes provided by the underlying platform. For example, on the JVM,
Stringis an alias forjava.lang.String.