Class ImmediateFuture<V>
- java.lang.Object
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- com.google.common.util.concurrent.ImmediateFuture<V>
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- All Implemented Interfaces:
ListenableFuture<V>
,java.util.concurrent.Future<V>
@GwtCompatible class ImmediateFuture<V> extends java.lang.Object implements ListenableFuture<V>
Implementation ofFutures.immediateFuture(V)
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Nested Class Summary
Nested Classes Modifier and Type Class Description (package private) static class
ImmediateFuture.ImmediateCancelledFuture<V>
(package private) static class
ImmediateFuture.ImmediateFailedFuture<V>
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Field Summary
Fields Modifier and Type Field Description private static java.util.logging.Logger
log
(package private) static ListenableFuture<?>
NULL
private V
value
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Constructor Summary
Constructors Constructor Description ImmediateFuture(V value)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addListener(java.lang.Runnable listener, java.util.concurrent.Executor executor)
Registers a listener to be run on the given executor.boolean
cancel(boolean mayInterruptIfRunning)
V
get()
V
get(long timeout, java.util.concurrent.TimeUnit unit)
boolean
isCancelled()
boolean
isDone()
java.lang.String
toString()
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Field Detail
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NULL
static final ListenableFuture<?> NULL
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log
private static final java.util.logging.Logger log
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value
private final V value
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Constructor Detail
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ImmediateFuture
ImmediateFuture(V value)
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Method Detail
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addListener
public void addListener(java.lang.Runnable listener, java.util.concurrent.Executor executor)
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: For fast, lightweight listeners that would be safe to execute in any thread, consider
MoreExecutors.directExecutor()
. Otherwise, avoid it. HeavyweightdirectExecutor
listeners 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
directExecutor
listeners.
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>
- 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
public boolean cancel(boolean mayInterruptIfRunning)
- Specified by:
cancel
in interfacejava.util.concurrent.Future<V>
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get
public V get(long timeout, java.util.concurrent.TimeUnit unit) throws java.util.concurrent.ExecutionException
- Specified by:
get
in interfacejava.util.concurrent.Future<V>
- Throws:
java.util.concurrent.ExecutionException
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isCancelled
public boolean isCancelled()
- Specified by:
isCancelled
in interfacejava.util.concurrent.Future<V>
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isDone
public boolean isDone()
- Specified by:
isDone
in interfacejava.util.concurrent.Future<V>
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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