Class SettableFuture<V>
- All Implemented Interfaces:
java.util.concurrent.Future<V>,ListenableFuture<V>
@GwtCompatible public final class SettableFuture<V> extends AbstractFuture<V>
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) - Author:
- Sven Mawson
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Method Summary
Modifier and Type Method Description voidaddListener(java.lang.Runnable listener, java.util.concurrent.Executor executor)Registers a listener to be run on the given executor.booleancancel(boolean mayInterruptIfRunning)static <V> SettableFuture<V>create()Creates a newSettableFuturethat can be completed or cancelled by a later method call.Vget()Vget(long timeout, java.util.concurrent.TimeUnit unit)booleanisCancelled()booleanisDone()booleanset(@Nullable V value)Sets the result of thisFutureunless thisFuturehas already been cancelled or set (including set asynchronously).booleansetException(java.lang.Throwable throwable)Sets the failed result of thisFutureunless thisFuturehas already been cancelled or set (including set asynchronously).booleansetFuture(ListenableFuture<? extends V> future)Sets the result of thisFutureto match the supplied inputFutureonce the suppliedFutureis done, unless thisFuturehas already been cancelled or set (including "set asynchronously," defined below).Methods inherited from class org.docx4j.com.google.common.util.concurrent.AbstractFuture
afterDone, interruptTask, pendingToString, toString, tryInternalFastPathGetFailure, wasInterrupted
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Method Details
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create
Creates a newSettableFuturethat can be completed or cancelled by a later method call. -
set
Description copied from class:AbstractFutureSets the result of thisFutureunless thisFuturehas already been cancelled or set (including set asynchronously). When a call to this method returns, theFutureis guaranteed to be done only if the call was accepted (in which case it returnstrue). If it returnsfalse, theFuturemay 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 aset*method, only by a call toAbstractFuture.cancel(boolean).- Overrides:
setin classAbstractFuture<V>- Parameters:
value- the value to be used as the result- Returns:
- true if the attempt was accepted, completing the
Future
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setException
@CanIgnoreReturnValue public boolean setException(java.lang.Throwable throwable)Description copied from class:AbstractFutureSets the failed result of thisFutureunless thisFuturehas already been cancelled or set (including set asynchronously). When a call to this method returns, theFutureis guaranteed to be done only if the call was accepted (in which case it returnstrue). If it returnsfalse, theFuturemay 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 aset*method, only by a call toAbstractFuture.cancel(boolean).- Overrides:
setExceptionin classAbstractFuture<V>- Parameters:
throwable- the exception to be used as the failed result- Returns:
- true if the attempt was accepted, completing the
Future
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setFuture
Description copied from class:AbstractFutureSets the result of thisFutureto match the supplied inputFutureonce the suppliedFutureis done, unless thisFuturehas 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 toAbstractFuture.cancel(boolean).If the call
setFuture(delegate)is accepted and thisFutureis later cancelled, cancellation will be propagated todelegate. Additionally, any call tosetFutureafter any cancellation will propagate cancellation to the suppliedFuture.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 theAbstractFuture.wasInterrupted()method will not returntrue.- Overrides:
setFuturein classAbstractFuture<V>- Parameters:
future- the future to delegate to- Returns:
- true if the attempt was accepted, indicating that the
Futurewas not previously cancelled or set.
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get
@CanIgnoreReturnValue public final V get() throws java.lang.InterruptedException, java.util.concurrent.ExecutionExceptionDescription copied from class:AbstractFutureThe default
AbstractFutureimplementation throwsInterruptedExceptionif the current thread is interrupted during the call, even if the value is already available.- Specified by:
getin interfacejava.util.concurrent.Future<V>- Overrides:
getin classAbstractFuture<V>- Throws:
java.lang.InterruptedExceptionjava.util.concurrent.ExecutionException
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get
@CanIgnoreReturnValue public final V get(long timeout, java.util.concurrent.TimeUnit unit) throws java.lang.InterruptedException, java.util.concurrent.ExecutionException, java.util.concurrent.TimeoutExceptionDescription copied from class:AbstractFutureThe default
AbstractFutureimplementation throwsInterruptedExceptionif the current thread is interrupted during the call, even if the value is already available.- Specified by:
getin interfacejava.util.concurrent.Future<V>- Overrides:
getin classAbstractFuture<V>- Throws:
java.lang.InterruptedExceptionjava.util.concurrent.ExecutionExceptionjava.util.concurrent.TimeoutException
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isDone
public final boolean isDone()- Specified by:
isDonein interfacejava.util.concurrent.Future<V>- Overrides:
isDonein classAbstractFuture<V>
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isCancelled
public final boolean isCancelled()- Specified by:
isCancelledin interfacejava.util.concurrent.Future<V>- Overrides:
isCancelledin classAbstractFuture<V>
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addListener
public final void addListener(java.lang.Runnable listener, java.util.concurrent.Executor executor)Description copied from class:AbstractFutureRegisters 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., aRejectedExecutionExceptionor an exception thrown by direct execution) will be caught and logged.Note: For fast, lightweight listeners that would be safe to execute in any thread, consider
MoreExecutors.directExecutor(). Otherwise, avoid it. HeavyweightdirectExecutorlisteners can cause problems, and these problems can be difficult to reproduce because they depend on timing. For example:- The listener may be executed by the caller of
addListener. That caller may be a UI thread or other latency-sensitive thread. This can harm UI responsiveness. - The listener may be executed by the thread that completes this
Future. That thread may be an internal system thread such as an RPC network thread. Blocking that thread may stall progress of the whole system. It may even cause a deadlock. - The listener may delay other listeners, even listeners that are not themselves
directExecutorlisteners.
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
ListenableFuturepromptly release references to listeners after executing them.- Specified by:
addListenerin interfaceListenableFuture<V>- Overrides:
addListenerin classAbstractFuture<V>- Parameters:
listener- the listener to run when the computation is completeexecutor- the executor to run the listener in
- The listener may be executed by the caller of
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cancel
@CanIgnoreReturnValue public final boolean cancel(boolean mayInterruptIfRunning)Description copied from class:AbstractFutureIf a cancellation attempt succeeds on a
Futurethat had previously been set asynchronously, then the cancellation will also be propagated to the delegateFuturethat was supplied in thesetFuturecall.Rather than override this method to perform additional cancellation work or cleanup, subclasses should override
AbstractFuture.afterDone(), consultingAbstractFuture.isCancelled()andAbstractFuture.wasInterrupted()as necessary. This ensures that the work is done even if the future is cancelled without a call tocancel, such as by callingsetFuture(cancelledFuture).- Specified by:
cancelin interfacejava.util.concurrent.Future<V>- Overrides:
cancelin classAbstractFuture<V>
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