java.util.concurrent
Class AbstractExecutorService
- Executor, 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.
}
| Future submit(Callable task) - Submits a value-returning task for execution and returns a
Future representing the pending results of the task.
|
| Future submit(Runnable task, T result) - Submits a Runnable task for execution and returns a Future
representing that task.
|
| List> invokeAll(Callable> tasks) - Executes the given tasks, returning a list of Futures holding
their status and results when all complete.
|
| List> invokeAll(Callable> 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.
|
protected | RunnableFuture newTaskFor(Callable callable) - Returns a RunnableFuture for the given callable task.
|
protected | RunnableFuture newTaskFor(Runnable runnable, T value) - Returns a RunnableFuture for the given runnable and default
value.
|
| T invokeAny(Callable> tasks) - Executes the given tasks, returning the result
of one that has completed successfully (i.e., without throwing
an exception), if any do.
|
| T invokeAny(Callable> 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.
|
Future> | submit(Runnable task) - Submits a Runnable task for execution and returns a Future
representing that task.
|
clone , equals , extends Object> getClass , finalize , hashCode , notify , notifyAll , toString , wait , wait , wait |
Future submit
public Future submit(Callable 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.
- Future submit in interface ExecutorService
task
- the task to submit
- a Future representing pending completion of the task
Future submit
public Future 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.
- Future submit in interface ExecutorService
task
- the task to submitresult
- the result to return
- a Future representing pending completion of the task
List> invokeAll
public List> invokeAll(Callable> tasks)
throws InterruptedException
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.
- List> invokeAll in interface ExecutorService
tasks
- the collection of tasks
- 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.
List> invokeAll
public List> invokeAll(Callable> tasks,
long timeout,
TimeUnit unit)
throws InterruptedException
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.
- List> invokeAll in interface ExecutorService
tasks
- the collection of taskstimeout
- the maximum time to waitunit
- the time unit of the timeout argument
- 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.
RunnableFuture newTaskFor
protected RunnableFuture newTaskFor(Callable callable)
Returns a RunnableFuture for the given callable task.
callable
- the callable task being wrapped
- 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.
RunnableFuture newTaskFor
protected RunnableFuture newTaskFor(Runnable runnable,
T value)
Returns a RunnableFuture for the given runnable and default
value.
runnable
- the runnable task being wrappedvalue
- the default value for the returned future
- 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.
T invokeAny
public T invokeAny(Callable> tasks)
throws InterruptedException,
ExecutionException
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.
- T invokeAny in interface ExecutorService
tasks
- the collection of tasks
- the result returned by one of the tasks
T invokeAny
public T invokeAny(Callable> tasks,
long timeout,
TimeUnit unit)
throws InterruptedException,
ExecutionException,
TimeoutException
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.
- T invokeAny in interface ExecutorService
tasks
- the collection of taskstimeout
- the maximum time to waitunit
- the time unit of the timeout argument
- the result returned by one of the tasks.
submit
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.
- submit in interface ExecutorService
task
- the task to submit
- a Future representing pending completion of the task