scala.concurrent.impl

# Future

#### trait Future[+T] extends Future[T] with Awaitable[T]

Source
  Future.scala

Linear Supertypes
Future[T], Awaitable[T], AnyRef, Any
Known Subclasses
DefaultPromise, KeptPromise, Promise
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1. Future
2. Future
3. Awaitable
4. AnyRef
5. Any

Visibility

1. Public
2. All

### Type Members

1. #### final class FutureWithFilter[+A] extends AnyRef

### Abstract Value Members

1. #### abstract def await(atMost: Duration)(implicit canawait: CanAwait): T

   Definition Classes
     Awaitable
   Annotations
     @implicitNotFound( msg = ... )

2. #### implicit abstract def executor: ExecutionContextImpl

3. #### abstract def newPromise[S]: Promise[S]

   Creates a new promise.

   Creates a new promise.

   Definition Classes
     Future

4. #### abstract def onComplete[U](func: (Try[T]) ⇒ U): Future.this.type

   When this future is completed, either through an exception, a timeout, or a value, apply the provided function.

   When this future is completed, either through an exception, a timeout, or a value, apply the provided function.

   If the future has already been completed, this will either be applied immediately or be scheduled asynchronously.

   Multiple callbacks may be registered; there is no guarantee that they will be executed in a particular order.

   Definition Classes
     Future → Future

5. #### abstract def value: Option[Try[T]]

   The contained value of this Future.

   The contained value of this Future. Before this Future is completed the value will be None. After completion the value will be Some(Right(t)) if it contains a valid result, or Some(Left(error)) if it contains an exception.

### Concrete Value Members

1. #### final def !=(arg0: AnyRef): Boolean

   Definition Classes
     AnyRef

2. #### final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

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

   Definition Classes
     Any

3. #### final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   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

4. #### final def ==(arg0: AnyRef): Boolean

   Definition Classes
     AnyRef

5. #### final def ==(arg0: Any): Boolean

   Test two objects for equality.

   Test two objects for equality. 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
     Any

6. #### def andThen[U](pf: PartialFunction[Try[T], U]): Future[T]

   Applies the side-effecting function to the result of this future, and returns a new future with the result of this future.

   Applies the side-effecting function to the result of this future, and returns a new future with the result of this future.

   This method allows one to enforce that the callbacks are executed in a specified order.

   Note that if one of the chained `andThen` callbacks throws an exception, that exception is not propagated to the subsequent `andThen` callbacks. Instead, the subsequent `andThen` callbacks are given the original value of this future.

   The following example prints out `5`:

        val f = future { 5 }
        f andThen {
          case r => sys.error("runtime exception")
        } andThen {
          case Failure(t) => println(t)
          case Success(v) => println(v)
        }

   Definition Classes
     Future

7. #### 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 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`.

8. #### def clone(): AnyRef

   Create a copy of the receiver object.

   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[lang]
   Definition Classes
     AnyRef
   Annotations
     @throws()
   Note

     not specified by SLS as a member of AnyRef

9. #### def collect[S](pf: PartialFunction[T, S]): Future[S]

   Creates a new future by mapping the value of the current future if the given partial function is defined at that value.

   Creates a new future by mapping the value of the current future if the given partial function is defined at that value.

   If the current future contains a value for which the partial function is defined, the new future will also hold that value. Otherwise, the resulting future will fail with a `NoSuchElementException`.

   If the current future fails or times out, the resulting future also fails or times out, respectively.

   Example:

        val f = future { -5 }
        val g = f collect {
          case x if x < 0 => -x
        }
        val h = f collect {
          case x if x > 0 => x * 2
        }
        await(0) g // evaluates to 5
        await(0) h // throw a NoSuchElementException

   Definition Classes
     Future

10. #### def either[U >: T](that: Future[U]): Future[U]

    Creates a new future which holds the result of either this future or `that` future, depending on which future was completed first.

    Creates a new future which holds the result of either this future or `that` future, depending on which future was completed first.

    Note: using this method yields nondeterministic dataflow programs.

    Example:

         val f = future { sys.error("failed") }
         val g = future { 5 }
         val h = f either g
         await(0) h // evaluates to either 5 or throws a runtime exception

    Definition Classes
      Future

11. #### final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

    Tests whether the argument (`arg0`) 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

12. #### def equals(arg0: Any): Boolean

    The equality method for reference types.

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

    See also `equals` in Any.

    returns

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

    Definition Classes
      AnyRef → Any

13. #### def failed: Future[Throwable]

    Returns a failed projection of this future.

    Returns a failed projection of this future.

    The failed projection is a future holding a value of type `Throwable`.

    It is completed with a value which is the throwable of the original future in case the original future is failed.

    It is failed with a `NoSuchElementException` if the original future is completed successfully.

    Blocking on this future returns a value if the original future is completed with an exception and throws a corresponding exception if the original future fails.

    Definition Classes
      Future

14. #### def fallbackTo[U >: T](that: Future[U]): Future[U]

    Creates a new future which holds the result of this future if it was completed successfully, or, if not, the result of the `that` future if `that` is completed successfully.

    Creates a new future which holds the result of this future if it was completed successfully, or, if not, the result of the `that` future if `that` is completed successfully. If both futures are failed, the resulting future holds the throwable object of the first future.

    Using this method will not cause concurrent programs to become nondeterministic.

    Example:

         val f = future { sys.error("failed") }
         val g = future { 5 }
         val h = f orElse g
         await(0) h // evaluates to 5

    Definition Classes
      Future

15. #### def filter(pred: (T) ⇒ Boolean): Future[T]

    Creates a new future by filtering the value of the current future with a predicate.

    Creates a new future by filtering the value of the current future with a predicate.

    If the current future contains a value which satisfies the predicate, the new future will also hold that value. Otherwise, the resulting future will fail with a `NoSuchElementException`.

    If the current future fails or times out, the resulting future also fails or times out, respectively.

    Example:

         val f = future { 5 }
         val g = f filter { _ % 2 == 1 }
         val h = f filter { _ % 2 == 0 }
         await(0) g // evaluates to 5
         await(0) h // throw a NoSuchElementException

    Definition Classes
      Future

16. #### 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 `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws()
    Note

      not specified by SLS as a member of AnyRef

17. #### def flatMap[S](f: (T) ⇒ Future[S]): Future[S]

    Creates a new future by applying a function to the successful result of this future, and returns the result of the function as the new future.

    Creates a new future by applying a function to the successful result of this future, and returns the result of the function as the new future. If this future is completed with an exception then the new future will also contain this exception.

    $forComprehensionExample

    Definition Classes
      Future

18. #### def foreach[U](f: (T) ⇒ U): Unit

    Asynchronously processes the value in the future once the value becomes available.

    Asynchronously processes the value in the future once the value becomes available.

    Will not be called if the future fails.

    Definition Classes
      Future

19. #### final def getClass(): Class[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

20. #### def hashCode(): Int

    The hashCode method for reference types.

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

    returns

      the hash code value for this object.

    Definition Classes
      AnyRef → Any

21. #### final def isCompleted: Boolean

    Tests whether this Future has been completed.

22. #### 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 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

23. #### def map[S](f: (T) ⇒ S): Future[S]

    Creates a new future by applying a function to the successful result of this future.

    Creates a new future by applying a function to the successful result of this future. If this future is completed with an exception then the new future will also contain this exception.

    $forComprehensionExample

    Definition Classes
      Future

24. #### final def mapTo[T](implicit m: Manifest[T]): Promise[T]

    Creates a new Future[A] which is completed with this Future's result if that conforms to A's erased type or a ClassCastException otherwise.

25. #### final def ne(arg0: AnyRef): Boolean

    Equivalent to `!(this eq that)`.

    Equivalent to `!(this eq that)`.

    returns

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

    Definition Classes
      AnyRef

26. #### 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
    Note

      not specified by SLS as a member of AnyRef

27. #### 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
    Note

      not specified by SLS as a member of AnyRef

28. #### def onFailure[U](callback: PartialFunction[Throwable, U]): Future.this.type

    When this future is completed with a failure (i.

    When this future is completed with a failure (i.e. with a throwable), apply the provided callback to the throwable.

    The future may contain a throwable object and this means that the future failed. Futures obtained through combinators have the same exception as the future they were obtained from. The following throwable objects are not contained in the future:

    - `Error` - errors are not contained within futures
    - `InterruptedException` - not contained within futures
    - all `scala.util.control.ControlThrowable` except `NonLocalReturnControl` - not contained within futures

    Instead, the future is completed with a ExecutionException with one of the exceptions above as the cause. If a future is failed with a `scala.runtime.NonLocalReturnControl`, it is completed with a value instead from that throwable instead instead.

    If the future has already been completed with a failure, this will either be applied immediately or be scheduled asynchronously.

    Will not be called in case that the future is completed with a value.

    Multiple callbacks may be registered; there is no guarantee that they will be executed in a particular order.

    Definition Classes
      Future

29. #### def onSuccess[U](pf: PartialFunction[T, U]): Future.this.type

    When this future is completed successfully (i.

    When this future is completed successfully (i.e. with a value), apply the provided partial function to the value if the partial function is defined at that value.

    If the future has already been completed with a value, this will either be applied immediately or be scheduled asynchronously.

    Multiple callbacks may be registered; there is no guarantee that they will be executed in a particular order.

    Definition Classes
      Future

30. #### def recover[U >: T](pf: PartialFunction[Throwable, U]): Future[U]

    Creates a new future that will handle any matching throwable that this future might contain.

    Creates a new future that will handle any matching throwable that this future might contain. If there is no match, or if this future contains a valid result then the new future will contain the same.

    Example:

         future (6 / 0) recover { case e: ArithmeticException ￢ﾇﾒ 0 } // result: 0
         future (6 / 0) recover { case e: NotFoundException   ￢ﾇﾒ 0 } // result: exception
         future (6 / 2) recover { case e: ArithmeticException ￢ﾇﾒ 0 } // result: 3

    Definition Classes
      Future

31. #### def recoverWith[U >: T](pf: PartialFunction[Throwable, Future[U]]): Future[U]

    Creates a new future that will handle any matching throwable that this future might contain by assigning it a value of another future.

    Creates a new future that will handle any matching throwable that this future might contain by assigning it a value of another future.

    If there is no match, or if this future contains a valid result then the new future will contain the same result.

    Example:

         val f = future { Int.MaxValue }
         future (6 / 0) recoverWith { case e: ArithmeticException => f } // result: Int.MaxValue

    Definition Classes
      Future

32. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

33. #### 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

34. #### final def wait(): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws()

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

    Definition Classes
      AnyRef
    Annotations
      @throws()

36. #### final def wait(arg0: Long): Unit

    Definition Classes
      AnyRef
    Annotations
      @throws()

37. #### final def withFilter(p: (T) ⇒ Boolean): FutureWithFilter[T]

    Used by for-comprehensions.

38. #### def zip[U](that: Future[U]): Future[(T, U)]

    Zips the values of `this` and `that` future, and creates a new future holding the tuple of their results.

    Zips the values of `this` and `that` future, and creates a new future holding the tuple of their results.

    If `this` future fails, the resulting future is failed with the throwable stored in `this`. Otherwise, if `that` future fails, the resulting future is failed with the throwable stored in `that`.

    Definition Classes
      Future

### Inherited from Future[T]

### Inherited from Awaitable[T]

### Inherited from AnyRef

### Inherited from Any