Module java.base

Package java.util.concurrent

Class AbstractExecutorService

java.lang.Object

java.util.concurrent.AbstractExecutorService

All Implemented Interfaces:

Executor, ExecutorService

Direct Known Subclasses:

ForkJoinPool, ThreadPoolExecutor

public abstract class AbstractExecutorService
extends Object
implements ExecutorService

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

Constructor Summary

Constructors

Constructor	Description
AbstractExecutorService()

Method Summary

Modifier and Type	Method	Description
protected <T> RunnableFuture<T>	newTaskFor(Runnable runnable, T value)	Returns a RunnableFuture for the given runnable and default value.
protected <T> RunnableFuture<T>	newTaskFor(Callable<T> callable)	Returns a RunnableFuture for the given callable 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.
<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.

Methods declared in interface java.util.concurrent.Executor

execute

Methods declared in interface java.util.concurrent.ExecutorService

awaitTermination, invokeAll, invokeAll, invokeAny, invokeAny, isShutdown, isTerminated, shutdown, shutdownNow

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AbstractExecutorService

public AbstractExecutorService()

Method Detail

newTaskFor

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

Returns a RunnableFuture for the given runnable and default value.

Type Parameters:

T - the type of the given 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

Since:

1.6

newTaskFor

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

Returns a RunnableFuture for the given callable task.

Type Parameters:

T - the type of the callable's result

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

Since:

1.6

submit

public Future<?> submit(Runnable task)

Description copied from interface: ExecutorService

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

Specified by:

submit in interface ExecutorService

Parameters:

task - the task to submit

Returns:

a Future representing pending completion of the task

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if the task is null

submit

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

Description copied from interface: ExecutorService

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.

Specified by:

submit in interface ExecutorService

Type Parameters:

T - the type of the result

Parameters:

task - the task to submit

result - the result to return

Returns:

a Future representing pending completion of the task

Throws:

RejectedExecutionException - if the task cannot be scheduled for execution

NullPointerException - if the task is null

submit

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

Description copied from interface: ExecutorService

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.

Specified by:

submit in interface ExecutorService

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 execution

NullPointerException - if the task is null