V
- the type of values the tasks of this service produce and consumeExecutorCompletionService
public interface CompletionService<V>
submit
tasks for execution. Consumers take
completed tasks and process their results in the order they complete. A CompletionService
can for example be used to manage asynchronous I/O, in which tasks that perform reads are submitted in one part of a program or system, and then acted upon in a different part of the program when the reads complete, possibly in a different order than they were requested. Typically, a CompletionService
relies on a separate Executor
to actually execute the tasks, in which case the CompletionService
only manages an internal completion queue. The ExecutorCompletionService
class provides an implementation of this approach.
Memory consistency effects: Actions in a thread prior to submitting a task to a CompletionService
happen-before actions taken by that task, which in turn happen-before actions following a successful return from the corresponding take()
.
Modifier and Type | Method | Description |
---|---|---|
Future |
poll() |
Retrieves and removes the Future representing the next completed task, or null if none are present. |
Future |
poll |
Retrieves and removes the Future representing the next completed task, waiting if necessary up to the specified wait time if none are yet present. |
Future |
submit |
Submits a Runnable task for execution and returns a Future representing that task. |
Future |
submit |
Submits a value-returning task for execution and returns a Future representing the pending results of the task. |
Future |
take() |
Retrieves and removes the Future representing the next completed task, waiting if none are yet present. |
Future<V> submit(Callable<V> task)
task
- the task to submitRejectedExecutionException
- if the task cannot be scheduled for executionNullPointerException
- if the task is nullFuture<V> submit(Runnable task, V result)
task
- the task to submitresult
- the result to return upon successful completionget()
method will return the given result value upon completionRejectedExecutionException
- if the task cannot be scheduled for executionNullPointerException
- if the task is nullFuture<V> take() throws InterruptedException
InterruptedException
- if interrupted while waitingFuture<V> poll()
null
if none are present.null
if none are presentFuture<V> poll(long timeout, TimeUnit unit) throws InterruptedException
timeout
- how long to wait before giving up, in units of unit
unit
- a TimeUnit
determining how to interpret the timeout
parameternull
if the specified waiting time elapses before one is presentInterruptedException
- if interrupted while waiting
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/concurrent/CompletionService.html