What is ExecutorService Interface In Java ?

Previously we have discussed about 

What is Executor Interface In Java ?

Interface ExecutorService

All Superinterfaces:

Executor

All Known Subinterfaces:

ScheduledExecutorService

All Known Implementing Classes:

AbstractExecutorService, ForkJoinPool, ScheduledThreadPoolExecutor, ThreadPoolExecutor

Declaration of ExecutorService:

public interface ExecutorService

extends Executor

The java.util.concurrent.ExecutorService interface represents an asynchronous execution mechanism which is capable of executing tasks in the background. An ExecutorService is thus very similar to a thread pool.

An ExecutorService can be shut down, which will cause it to reject new tasks. Two different methods are provided for shutting down an ExecutorService. The shutdown() method will allow previously submitted tasks to execute before terminating, while the shutdownNow() method prevents waiting tasks from starting and attempts to stop currently executing tasks.

Method submit() extends base method Executor.execute(java.lang.Runnable) by creating and returning a Future that can be used to cancel execution and/or wait for completion.

Methods invokeAny() and invokeAll() perform the most commonly useful forms of bulk execution, executing a collection of tasks and then waiting for at least one, or all, to complete.

The Executors class provides factory methods for the executor services provided in this package.

Method Summary of ExecutorService Interface:

Modifier and Method Name	Description
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.
<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.
boolean isShutdown()	Returns true if this executor has been shut down.
boolean isTerminated()	Returns true if all tasks have completed following shut down.
void shutdown()	Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
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.
<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.
Future<?> submit(Runnable task)	Submits a Runnable task for execution and returns a Future representing that task.
<T> Future<T> submit(Runnable task, T result)	Submits a Runnable task for execution and returns a Future representing that task.

      

Blog Author - Pushkar Khosla,
Software Developer by Profession with 3.0 Yrs of Experience , through this blog i'am sharing my industrial Java Knowledge to entire world. For any question or query any one can comment below or mail me at pushkar.itsitm52@gmail.com.

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