Class AbstractExecutorService

java.lang.Object
java.util.concurrent.AbstractExecutorService
All Implemented Interfaces:
AutoCloseable, Executor, ExecutorService
Direct Known Subclasses:
ForkJoinPool, ThreadPoolExecutor
public abstract class AbstractExecutorService extends Object implements ExecutorService
Provides default implementations of ExecutorService methods other than Executor.execute(Runnable). 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()
    Constructor for subclasses to call.

  • Method Summary

    Modifier and Type
    Method
    Description
    <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.
    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 class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    Modifier and Type
    Method
    Description
    protected Object
    clone()
    Creates and returns a copy of this object.
    boolean
    equals(Object obj)
    Indicates whether some other object is "equal to" this one.
    protected void
    finalize()
    Deprecated, for removal: This API element is subject to removal in a future version.
    Finalization is deprecated and subject to removal in a future release.
    final Class<?>
    getClass()
    Returns the runtime class of this Object.
    int
    hashCode()
    Returns a hash code value for this object.
    final void
    notify()
    Wakes up a single thread that is waiting on this object's monitor.
    final void
    notifyAll()
    Wakes up all threads that are waiting on this object's monitor.
    String
    toString()
    Returns a string representation of the object.
    final void
    wait()
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
    final void
    wait(long timeoutMillis)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
    final void
    wait(long timeoutMillis, int nanos)
    Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

    Methods declared in interface Executor

    execute
    Modifier and Type
    Method
    Description
    void
    execute(Runnable command)
    Executes the given command at some time in the future.

    Methods declared in interface ExecutorService

    awaitTermination, close, isShutdown, isTerminated, shutdown, shutdownNow
    Modifier and Type
    Method
    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.
    default void
    close()
    Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
    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.

  • Constructor Details

    • AbstractExecutorService

      public AbstractExecutorService()
      Constructor for subclasses to call.

  • Method Details

    • 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

    • invokeAny

      public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException
      Description copied from interface: ExecutorService
      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.
      Specified by:
      invokeAny in interface ExecutorService
      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 waiting
      NullPointerException - if tasks or any element task subject to execution is null
      IllegalArgumentException - if tasks is empty
      ExecutionException - if no task successfully completes
      RejectedExecutionException - if tasks cannot be scheduled for execution

    • invokeAny

      public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException
      Description copied from interface: ExecutorService
      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.
      Specified by:
      invokeAny in interface ExecutorService
      Type Parameters:
      T - the type of the values returned from the tasks
      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 - if interrupted while waiting
      NullPointerException - if tasks, or unit, or any element task subject to execution is null
      TimeoutException - if the given timeout elapses before any task successfully completes
      ExecutionException - if no task successfully completes
      RejectedExecutionException - if tasks cannot be scheduled for execution

    • invokeAll

      public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException
      Description copied from interface: ExecutorService
      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.
      Specified by:
      invokeAll in interface ExecutorService
      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
      NullPointerException - if tasks or any of its elements are null
      RejectedExecutionException - if any task cannot be scheduled for execution

    • invokeAll

      public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException
      Description copied from interface: ExecutorService
      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.
      Specified by:
      invokeAll in interface ExecutorService
      Type Parameters:
      T - the type of the values returned from the tasks
      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 - if interrupted while waiting, in which case unfinished tasks are cancelled
      NullPointerException - if tasks, any of its elements, or unit are null
      RejectedExecutionException - if any task cannot be scheduled for execution