| java.util.concurrent.CompletionService<V> |
 Known Indirect Subclasses
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A service that decouples the production of new asynchronous tasks from the consumption of the results of completed tasks. Producers 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 IO, 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().
| Public Methods | |||||||||||
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Retrieves and removes the Future representing the next
completed task or null if none are present.
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Retrieves and removes the Future representing the next
completed task, waiting if necessary up to the specified wait
time if none are yet present.
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Submits a value-returning task for execution and returns a Future
representing the pending results of the task.
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Submits a Runnable task for execution and returns a Future
representing that task.
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Retrieves and removes the Future representing the next
completed task, waiting if none are yet present.
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Retrieves and removes the Future representing the next completed task or null if none are present.
Retrieves and removes the Future representing the next completed task, waiting if necessary up to the specified wait time if none are yet present.
| timeout | how long to wait before giving up, in units of unit |
|---|---|
| unit | a TimeUnit determining how to interpret the timeout parameter |
| InterruptedException | if interrupted while waiting |
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Submits a value-returning task for execution and returns a Future representing the pending results of the task. Upon completion, this task may be taken or polled.
| task | the task to submit |
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| RejectedExecutionException | if the task cannot be scheduled for execution |
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| NullPointerException | if the task is null |
Submits a Runnable task for execution and returns a Future representing that task. Upon completion, this task may be taken or polled.
| task | the task to submit |
|---|---|
| result | the result to return upon successful completion |
| RejectedExecutionException | if the task cannot be scheduled for execution |
|---|---|
| NullPointerException | if the task is null |
Retrieves and removes the Future representing the next completed task, waiting if none are yet present.
| InterruptedException | if interrupted while waiting |
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