java.lang.Object
java.util.concurrent.AbstractExecutorService
- All Implemented Interfaces:
Executor,ExecutorService
- Direct Known Subclasses:
ForkJoinPool,ThreadPoolExecutor
Provides default implementations of
ExecutorService
execution methods. This class implements the submit,
invokeAny and invokeAll methods using a
RunnableFuture returned by newTaskFor, which defaults
to the FutureTask class provided in this package. For example,
the implementation of submit(Runnable) creates an
associated RunnableFuture that is executed and
returned. Subclasses may override the newTaskFor methods
to return RunnableFuture implementations other than
FutureTask.
Extension example. Here is a sketch of a class
that customizes ThreadPoolExecutor to use
a CustomTask class instead of the default FutureTask:
public class CustomThreadPoolExecutor extends ThreadPoolExecutor {
static class CustomTask<V> implements RunnableFuture<V> { ... }
protected <V> RunnableFuture<V> newTaskFor(Callable<V> c) {
return new CustomTask<V>(c);
}
protected <V> RunnableFuture<V> newTaskFor(Runnable r, V v) {
return new CustomTask<V>(r, v);
}
// ... add constructors, etc.
}- Since:
- 1.5
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptioninvokeAll(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning a list of Futures holding their status and results when all complete.invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first.<T> TinvokeAny(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do.<T> TinvokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses.protected <T> RunnableFuture<T>newTaskFor(Runnable runnable, T value) Returns aRunnableFuturefor the given runnable and default value.protected <T> RunnableFuture<T>newTaskFor(Callable<T> callable) Returns aRunnableFuturefor the given callable task.Future<?>Submits a Runnable task for execution and returns a Future representing that task.<T> Future<T>Submits a Runnable task for execution and returns a Future representing that task.<T> Future<T>Submits a value-returning task for execution and returns a Future representing the pending results of the task.Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitMethods declared in interface java.util.concurrent.ExecutorService
awaitTermination, isShutdown, isTerminated, shutdown, shutdownNow
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Constructor Details
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AbstractExecutorService
public AbstractExecutorService()Constructor for subclasses to call.
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Method Details
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newTaskFor
Returns aRunnableFuturefor the given runnable and default value.- Type Parameters:
T- the type of the given value- Parameters:
runnable- the runnable task being wrappedvalue- the default value for the returned future- Returns:
- a
RunnableFuturewhich, when run, will run the underlying runnable and which, as aFuture, will yield the given value as its result and provide for cancellation of the underlying task - Since:
- 1.6
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newTaskFor
Returns aRunnableFuturefor the given callable task.- Type Parameters:
T- the type of the callable's result- Parameters:
callable- the callable task being wrapped- Returns:
- a
RunnableFuturewhich, when run, will call the underlying callable and which, as aFuture, will yield the callable's result as its result and provide for cancellation of the underlying task - Since:
- 1.6
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submit
Description copied from interface:ExecutorServiceSubmits a Runnable task for execution and returns a Future representing that task. The Future'sgetmethod will returnnullupon successful completion.- Specified by:
submitin interfaceExecutorService- Parameters:
task- the task to submit- Returns:
- a Future representing pending completion of the task
- Throws:
RejectedExecutionException- if the task cannot be scheduled for executionNullPointerException- if the task is null
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submit
Description copied from interface:ExecutorServiceSubmits a Runnable task for execution and returns a Future representing that task. The Future'sgetmethod will return the given result upon successful completion.- Specified by:
submitin interfaceExecutorService- Type Parameters:
T- the type of the result- Parameters:
task- the task to submitresult- the result to return- Returns:
- a Future representing pending completion of the task
- Throws:
RejectedExecutionException- if the task cannot be scheduled for executionNullPointerException- if the task is null
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submit
Description copied from interface:ExecutorServiceSubmits a value-returning task for execution and returns a Future representing the pending results of the task. The Future'sgetmethod will return the task's result upon successful completion.If you would like to immediately block waiting for a task, you can use constructions of the form
result = exec.submit(aCallable).get();Note: The
Executorsclass includes a set of methods that can convert some other common closure-like objects, for example,PrivilegedActiontoCallableform so they can be submitted.- Specified by:
submitin interfaceExecutorService- Type Parameters:
T- the type of the task's result- Parameters:
task- the task to submit- Returns:
- a Future representing pending completion of the task
- Throws:
RejectedExecutionException- if the task cannot be scheduled for executionNullPointerException- if the task is null
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invokeAny
public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException Description copied from interface:ExecutorServiceExecutes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress.- Specified by:
invokeAnyin interfaceExecutorService- Type Parameters:
T- the type of the values returned from the tasks- Parameters:
tasks- the collection of tasks- Returns:
- the result returned by one of the tasks
- Throws:
InterruptedException- if interrupted while waitingExecutionException- if no task successfully completes
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invokeAny
public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException Description copied from interface:ExecutorServiceExecutes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress.- Specified by:
invokeAnyin interfaceExecutorService- Type Parameters:
T- the type of the values returned from the tasks- Parameters:
tasks- the collection of taskstimeout- the maximum time to waitunit- the time unit of the timeout argument- Returns:
- the result returned by one of the tasks
- Throws:
InterruptedException- if interrupted while waitingExecutionException- if no task successfully completesTimeoutException- if the given timeout elapses before any task successfully completes
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invokeAll
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException Description copied from interface:ExecutorServiceExecutes the given tasks, returning a list of Futures holding their status and results when all complete.Future.isDone()istruefor each element of the returned list. Note that a completed task could have terminated either normally or by throwing an exception. The results of this method are undefined if the given collection is modified while this operation is in progress.- Specified by:
invokeAllin interfaceExecutorService- Type Parameters:
T- the type of the values returned from the tasks- Parameters:
tasks- the collection of tasks- Returns:
- a list of Futures representing the tasks, in the same sequential order as produced by the iterator for the given task list, each of which has completed
- Throws:
InterruptedException- if interrupted while waiting, in which case unfinished tasks are cancelled
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invokeAll
public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException Description copied from interface:ExecutorServiceExecutes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first.Future.isDone()istruefor each element of the returned list. Upon return, tasks that have not completed are cancelled. Note that a completed task could have terminated either normally or by throwing an exception. The results of this method are undefined if the given collection is modified while this operation is in progress.- Specified by:
invokeAllin interfaceExecutorService- Type Parameters:
T- the type of the values returned from the tasks- Parameters:
tasks- the collection of taskstimeout- the maximum time to waitunit- the time unit of the timeout argument- Returns:
- a list of Futures representing the tasks, in the same sequential order as produced by the iterator for the given task list. If the operation did not time out, each task will have completed. If it did time out, some of these tasks will not have completed.
- Throws:
InterruptedException- if interrupted while waiting, in which case unfinished tasks are cancelled
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