Class SettableFuture<V>

All Implemented Interfaces:
AbstractFuture.Trusted<V>, ListenableFuture<V>, Future<V>

public final class SettableFuture<V> extends AbstractFuture.TrustedFuture<V>
A ListenableFuture whose result can be set by a set(Object), setException(Throwable) or setFuture(ListenableFuture) call. It can also, like any other Future, be cancelled.

SettableFuture is the recommended ListenableFuture implementation when your task cannot be implemented with ListeningExecutorService, the various Futures utility methods, or ListenableFutureTask. Those APIs have less opportunity for developer error. If your needs are more complex than SettableFuture supports, use AbstractFuture, which offers an extensible version of the API.

Since:
9.0 (in 1.0 as ValueFuture)
  • Constructor Details

    • SettableFuture

      private SettableFuture()
  • Method Details

    • create

      public static <V> SettableFuture<V> create()
      Creates a new SettableFuture that can be completed or cancelled by a later method call.
    • set

      public boolean set(V value)
      Description copied from class: AbstractFuture
      Sets the result of this Future unless this Future has already been cancelled or set (including set asynchronously). When a call to this method returns, the Future is guaranteed to be done only if the call was accepted (in which case it returns true). If it returns false, the Future may have previously been set asynchronously, in which case its result may not be known yet. That result, though not yet known, cannot be overridden by a call to a set* method, only by a call to AbstractFuture.cancel(boolean).

      Beware of completing a future while holding a lock. Its listeners may do slow work or acquire other locks, risking deadlocks.

      Overrides:
      set in class AbstractFuture<V>
      Parameters:
      value - the value to be used as the result
      Returns:
      true if the attempt was accepted, completing the Future
    • setException

      public boolean setException(Throwable throwable)
      Description copied from class: AbstractFuture
      Sets the failed result of this Future unless this Future has already been cancelled or set (including set asynchronously). When a call to this method returns, the Future is guaranteed to be done only if the call was accepted (in which case it returns true). If it returns false, the Future may have previously been set asynchronously, in which case its result may not be known yet. That result, though not yet known, cannot be overridden by a call to a set* method, only by a call to AbstractFuture.cancel(boolean).

      Beware of completing a future while holding a lock. Its listeners may do slow work or acquire other locks, risking deadlocks.

      Overrides:
      setException in class AbstractFuture<V>
      Parameters:
      throwable - the exception to be used as the failed result
      Returns:
      true if the attempt was accepted, completing the Future
    • setFuture

      public boolean setFuture(ListenableFuture<? extends V> future)
      Description copied from class: AbstractFuture
      Sets the result of this Future to match the supplied input Future once the supplied Future is done, unless this Future has already been cancelled or set (including "set asynchronously," defined below).

      If the supplied future is done when this method is called and the call is accepted, then this future is guaranteed to have been completed with the supplied future by the time this method returns. If the supplied future is not done and the call is accepted, then the future will be set asynchronously. Note that such a result, though not yet known, cannot be overridden by a call to a set* method, only by a call to AbstractFuture.cancel(boolean).

      If the call setFuture(delegate) is accepted and this Future is later cancelled, cancellation will be propagated to delegate. Additionally, any call to setFuture after any cancellation will propagate cancellation to the supplied Future.

      Note that, even if the supplied future is cancelled and it causes this future to complete, it will never trigger interruption behavior. In particular, it will not cause this future to invoke the AbstractFuture.interruptTask() method, and the AbstractFuture.wasInterrupted() method will not return true.

      Beware of completing a future while holding a lock. Its listeners may do slow work or acquire other locks, risking deadlocks.

      Overrides:
      setFuture in class AbstractFuture<V>
      Parameters:
      future - the future to delegate to
      Returns:
      true if the attempt was accepted, indicating that the Future was not previously cancelled or set.