AbstractExecutorService

public abstract class AbstractExecutorService extends Object
implements ExecutorService

Known Direct Subclasses ForkJoinPool, ThreadPoolExecutor ForkJoinPool An ExecutorService for running ForkJoinTasks.  ThreadPoolExecutor An ExecutorService that executes each submitted task using one of possibly several pooled threads, normally configured using Executors factory methods.

Known Indirect Subclasses ScheduledThreadPoolExecutor ScheduledThreadPoolExecutor A ThreadPoolExecutor that can additionally schedule commands to run after a given delay, or to execute periodically.

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.
 }

Public Constructor Summary

AbstractExecutorService()

Public Method Summary

<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning a list of Futures holding their status and results when all complete.
<T> List<Future<T>>	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> T	invokeAny(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> T	invokeAny(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.
<T> Future<T>	submit(Callable<T> task) Submits a value-returning task for execution and returns a Future representing the pending results of the task.
<T> Future<T>	submit(Runnable task, T result) Submits a Runnable task for execution and returns a Future representing that task.
Future<?>	submit(Runnable task) Submits a Runnable task for execution and returns a Future representing that task.

Protected Method Summary

<T> RunnableFuture<T>	newTaskFor(Runnable runnable, T value) Returns a RunnableFuture for the given runnable and default value.
<T> RunnableFuture<T>	newTaskFor(Callable<T> callable) Returns a RunnableFuture for the given callable task.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

From interface java.util.concurrent.ExecutorService

abstract boolean	awaitTermination(long timeout, TimeUnit unit) Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
abstract <T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks) Executes the given tasks, returning a list of Futures holding their status and results when all complete.
abstract <T> List<Future<T>>	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.
abstract <T> T	invokeAny(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.
abstract <T> T	invokeAny(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.
abstract boolean	isShutdown() Returns true if this executor has been shut down.
abstract boolean	isTerminated() Returns true if all tasks have completed following shut down.
abstract void	shutdown() Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
abstract List<Runnable>	shutdownNow() Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.
abstract <T> Future<T>	submit(Callable<T> task) Submits a value-returning task for execution and returns a Future representing the pending results of the task.
abstract <T> Future<T>	submit(Runnable task, T result) Submits a Runnable task for execution and returns a Future representing that task.
abstract Future<?>	submit(Runnable task) Submits a Runnable task for execution and returns a Future representing that task.

From interface java.util.concurrent.Executor

abstract void

execute(Runnable command) Executes the given command at some time in the future.

Public Constructors

public AbstractExecutorService ()

Public Methods

public List<Future<T>> invokeAll (Collection<? extends Callable<T>> tasks)

Executes the given tasks, returning a list of Futures holding their status and results when all complete. Future.isDone() is true for 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.

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

public List<Future<T>> 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. Future.isDone() is true for 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.

Parameters

tasks	the collection of tasks
timeout	the maximum time to wait
unit	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

public T invokeAny (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. 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.

Parameters

tasks	the collection of tasks

Returns

• the result returned by one of the tasks

Throws

InterruptedException
ExecutionException

public T invokeAny (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. 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.

Parameters

tasks	the collection of tasks
timeout	the maximum time to wait
unit	the time unit of the timeout argument

Returns

• the result returned by one of the tasks

Throws

InterruptedException
ExecutionException
TimeoutException

public Future<T> submit (Callable<T> task)

Submits a value-returning task for execution and returns a Future representing the pending results of the task. The Future's get method 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 Executors class includes a set of methods that can convert some other common closure-like objects, for example, PrivilegedAction to Callable form so they can be submitted.

Parameters

task	the task to submit

Returns

• a Future representing pending completion of the task

Throws

RejectedExecutionException
NullPointerException

public Future<T> submit (Runnable task, T result)

Submits a Runnable task for execution and returns a Future representing that task. The Future's get method will return the given result upon successful completion.

Parameters

task	the task to submit
result	the result to return

Returns

• a Future representing pending completion of the task

Throws

RejectedExecutionException
NullPointerException

public Future<?> submit (Runnable task)

Submits a Runnable task for execution and returns a Future representing that task. The Future's get method will return null upon successful completion.

Parameters

task	the task to submit

Returns

• a Future representing pending completion of the task

Throws

RejectedExecutionException
NullPointerException

Protected Methods

protected RunnableFuture<T> newTaskFor (Runnable runnable, T value)

Returns a RunnableFuture for the given runnable and default value.

Parameters

runnable	the runnable task being wrapped
value	the default value for the returned future

Returns

• a RunnableFuture which, when run, will run the underlying runnable and which, as a Future, will yield the given value as its result and provide for cancellation of the underlying task

protected RunnableFuture<T> newTaskFor (Callable<T> callable)

Returns a RunnableFuture for the given callable task.

Parameters

callable	the callable task being wrapped

Returns

• a RunnableFuture which, when run, will call the underlying callable and which, as a Future, will yield the callable's result as its result and provide for cancellation of the underlying task