- All Implemented Interfaces:
ListenableFuture<V>
,Future<V>
- Direct Known Subclasses:
ForwardingListenableFuture.SimpleForwardingListenableFuture
ListenableFuture
which forwards all its method calls to another future. Subclasses
should override one or more methods to modify the behavior of the backing future as desired per
the decorator pattern.
Most subclasses can just use ForwardingListenableFuture.SimpleForwardingListenableFuture
.
- Since:
- 4.0
- Author:
- Shardul Deo
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
A simplified version ofForwardingListenableFuture
where subclasses can pass in an already constructedListenableFuture
as the delegate.Nested classes/interfaces inherited from class com.google.common.util.concurrent.ForwardingFuture
ForwardingFuture.SimpleForwardingFuture<V extends @Nullable Object>
Nested classes/interfaces inherited from interface java.util.concurrent.Future
Future.State
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
Constructor for use by subclasses. -
Method Summary
Modifier and TypeMethodDescriptionvoid
addListener
(Runnable listener, Executor exec) Registers a listener to be run on the given executor.protected abstract ListenableFuture
<? extends V> delegate()
Returns the backing delegate instance that methods are forwarded to.Methods inherited from class com.google.common.util.concurrent.ForwardingFuture
cancel, get, get, isCancelled, isDone
Methods inherited from class com.google.common.collect.ForwardingObject
toString
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.concurrent.Future
cancel, exceptionNow, get, get, isCancelled, isDone, resultNow, state
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Constructor Details
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ForwardingListenableFuture
protected ForwardingListenableFuture()Constructor for use by subclasses.
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Method Details
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delegate
Description copied from class:ForwardingObject
Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such asForwardingSet.delegate()
. Concrete subclasses override this method to supply the instance being decorated.- Specified by:
delegate
in classForwardingFuture<V extends @Nullable Object>
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addListener
Description copied from interface:ListenableFuture
Registers a listener to be run on the given executor. The listener will run when theFuture
's computation is complete or, if the computation is already complete, immediately.There is no guaranteed ordering of execution of listeners, but any listener added through this method is guaranteed to be called once the computation is complete.
Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown during
Executor.execute
(e.g., aRejectedExecutionException
or an exception thrown by direct execution) will be caught and logged.Note: If your listener is lightweight -- and will not cause stack overflow by completing more futures or adding more
directExecutor()
listeners inline -- considerMoreExecutors.directExecutor()
. Otherwise, avoid it: See the warnings on the docs fordirectExecutor
.This is the most general listener interface. For common operations performed using listeners, see
Futures
. For a simplified but general listener interface, seeaddCallback()
.Memory consistency effects: Actions in a thread prior to adding a listener happen-before its execution begins, perhaps in another thread.
Guava implementations of
ListenableFuture
promptly release references to listeners after executing them.- Specified by:
addListener
in interfaceListenableFuture<V extends @Nullable Object>
- Parameters:
listener
- the listener to run when the computation is completeexec
- the executor to run the listener in
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