| java.lang.Object
 java.util.concurrent.Executors
| Executors | | public class Executors (Code) | | Factory and utility methods for
Executor ,
ExecutorService ,
ScheduledExecutorService ,
ThreadFactory , and
Callable classes defined in this
package. This class supports the following kinds of methods:
- Methods that create and return an
ExecutorService set up with commonly useful configuration settings.
- Methods that create and return a
ScheduledExecutorService set up with commonly useful configuration settings.
- Methods that create and return a "wrapped" ExecutorService, that
disables reconfiguration by making implementation-specific methods
inaccessible.
- Methods that create and return a
ThreadFactory that sets newly created threads to a known state.
- Methods that create and return a
Callable out of other closure-like forms, so they can be used
in execution methods requiring Callable.
since:
1.5
author:
Doug Lea |
| Inner Class :final static class RunnableAdapter implements Callable<T> | |
| Inner Class :final static class PrivilegedCallable implements Callable<T> | |
| Inner Class :final static class PrivilegedCallableUsingCurrentClassLoader implements Callable<T> | |
| Inner Class :static class DefaultThreadFactory implements ThreadFactory | |
| Inner Class :static class PrivilegedThreadFactory extends DefaultThreadFactory | |
| Inner Class :static class FinalizableDelegatedExecutorService extends DelegatedExecutorService | |
| Inner Class :static class DelegatedScheduledExecutorService extends DelegatedExecutorService implements ScheduledExecutorService | |
| Method Summary | |
| public static Callable<T> | callable(Runnable task, T result)
Returns a
Callable object that, when
called, runs the given task and returns the given result. | | public static Callable<Object> | callable(Runnable task)
Returns a
Callable object that, when
called, runs the given task and returns null. | | public static Callable<Object> | callable(PrivilegedAction action)
Returns a
Callable object that, when
called, runs the given privileged action and returns its result. | | public static Callable<Object> | callable(PrivilegedExceptionAction action)
Returns a
Callable object that, when
called, runs the given privileged exception action and returns
its result. | | public static ThreadFactory | defaultThreadFactory()
Returns a default thread factory used to create new threads.
This factory creates all new threads used by an Executor in the
same
ThreadGroup . | | public static ExecutorService | newCachedThreadPool()
Creates a thread pool that creates new threads as needed, but
will reuse previously constructed threads when they are
available. | | public static ExecutorService | newCachedThreadPool(ThreadFactory threadFactory)
Creates a thread pool that creates new threads as needed, but
will reuse previously constructed threads when they are
available, and uses the provided
ThreadFactory to create new threads when needed. | | public static ExecutorService | newFixedThreadPool(int nThreads)
Creates a thread pool that reuses a fixed number of threads
operating off a shared unbounded queue. | | public static ExecutorService | newFixedThreadPool(int nThreads, ThreadFactory threadFactory)
Creates a thread pool that reuses a fixed number of threads
operating off a shared unbounded queue, using the provided
ThreadFactory to create new threads when needed. | | public static ScheduledExecutorService | newScheduledThreadPool(int corePoolSize)
Creates a thread pool that can schedule commands to run after a
given delay, or to execute periodically.
Parameters:
corePoolSize - the number of threads to keep in the pool,even if they are idle. | | public static ScheduledExecutorService | newScheduledThreadPool(int corePoolSize, ThreadFactory threadFactory)
Creates a thread pool that can schedule commands to run after a
given delay, or to execute periodically.
Parameters:
corePoolSize - the number of threads to keep in the pool,even if they are idle.
Parameters:
threadFactory - the factory to use when the executorcreates a new thread. | | public static ExecutorService | newSingleThreadExecutor()
Creates an Executor that uses a single worker thread operating
off an unbounded queue. | | public static ExecutorService | newSingleThreadExecutor(ThreadFactory threadFactory)
Creates an Executor that uses a single worker thread operating
off an unbounded queue, and uses the provided ThreadFactory to
create a new thread when needed. | | public static ScheduledExecutorService | newSingleThreadScheduledExecutor()
Creates a single-threaded executor that can schedule commands
to run after a given delay, or to execute periodically.
(Note however that if this single
thread terminates due to a failure during execution prior to
shutdown, a new one will take its place if needed to execute
subsequent tasks.) Tasks are guaranteed to execute
sequentially, and no more than one task will be active at any
given time. | | public static ScheduledExecutorService | newSingleThreadScheduledExecutor(ThreadFactory threadFactory)
Creates a single-threaded executor that can schedule commands
to run after a given delay, or to execute periodically. | | public static Callable<T> | privilegedCallable(Callable<T> callable)
Returns a
Callable object that will, when
called, execute the given callable under the current
access control context. | | public static Callable<T> | privilegedCallableUsingCurrentClassLoader(Callable<T> callable)
Returns a
Callable object that will, when
called, execute the given callable under the current
access control context, with the current context class loader
as the context class loader. | | public static ThreadFactory | privilegedThreadFactory()
Returns a thread factory used to create new threads that
have the same permissions as the current thread.
This factory creates threads with the same settings as
Executors.defaultThreadFactory , additionally setting the
AccessControlContext and contextClassLoader of new threads to
be the same as the thread invoking this
privilegedThreadFactory method. | | public static ExecutorService | unconfigurableExecutorService(ExecutorService executor)
Returns an object that delegates all defined
ExecutorService methods to the given executor, but not any
other methods that might otherwise be accessible using
casts. | | public static ScheduledExecutorService | unconfigurableScheduledExecutorService(ScheduledExecutorService executor)
Returns an object that delegates all defined
ScheduledExecutorService methods to the given executor, but
not any other methods that might otherwise be accessible using
casts. |
| callable | | public static Callable<T> callable(Runnable task, T result)(Code) | | Returns a
Callable object that, when
called, runs the given task and returns the given result. This
can be useful when applying methods requiring a
Callable to an otherwise resultless action.
Parameters:
task - the task to run
Parameters:
result - the result to return a callable object
throws:
NullPointerException - if task null |
| defaultThreadFactory | | public static ThreadFactory defaultThreadFactory()(Code) | | Returns a default thread factory used to create new threads.
This factory creates all new threads used by an Executor in the
same
ThreadGroup . If there is a
java.lang.SecurityManager , it uses the group of
System.getSecurityManager , else the group of the thread
invoking this defaultThreadFactory method. Each new
thread is created as a non-daemon thread with priority set to
the smaller of Thread.NORM_PRIORITY and the maximum
priority permitted in the thread group. New threads have names
accessible via
Thread.getName of
pool-N-thread-M, where N is the sequence
number of this factory, and M is the sequence number
of the thread created by this factory.
a thread factory |
| newCachedThreadPool | | public static ExecutorService newCachedThreadPool()(Code) | | Creates a thread pool that creates new threads as needed, but
will reuse previously constructed threads when they are
available. These pools will typically improve the performance
of programs that execute many short-lived asynchronous tasks.
Calls to execute will reuse previously constructed
threads if available. If no existing thread is available, a new
thread will be created and added to the pool. Threads that have
not been used for sixty seconds are terminated and removed from
the cache. Thus, a pool that remains idle for long enough will
not consume any resources. Note that pools with similar
properties but different details (for example, timeout parameters)
may be created using
ThreadPoolExecutor constructors.
the newly created thread pool |
| newCachedThreadPool | | public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory)(Code) | | Creates a thread pool that creates new threads as needed, but
will reuse previously constructed threads when they are
available, and uses the provided
ThreadFactory to create new threads when needed.
Parameters:
threadFactory - the factory to use when creating new threads the newly created thread pool
throws:
NullPointerException - if threadFactory is null |
| newFixedThreadPool | | public static ExecutorService newFixedThreadPool(int nThreads)(Code) | | Creates a thread pool that reuses a fixed number of threads
operating off a shared unbounded queue. At any point, at most
nThreads threads will be active processing tasks.
If additional tasks are submitted when all threads are active,
they will wait in the queue until a thread is available.
If any thread terminates due to a failure during execution
prior to shutdown, a new one will take its place if needed to
execute subsequent tasks. The threads in the pool will exist
until it is explicitly
ExecutorService.shutdown shutdown .
Parameters:
nThreads - the number of threads in the pool the newly created thread pool
throws:
IllegalArgumentException - if nThreads <= 0 |
| newFixedThreadPool | | public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory)(Code) | | Creates a thread pool that reuses a fixed number of threads
operating off a shared unbounded queue, using the provided
ThreadFactory to create new threads when needed. At any point,
at most nThreads threads will be active processing
tasks. If additional tasks are submitted when all threads are
active, they will wait in the queue until a thread is
available. If any thread terminates due to a failure during
execution prior to shutdown, a new one will take its place if
needed to execute subsequent tasks. The threads in the pool will
exist until it is explicitly
ExecutorService.shutdownshutdown .
Parameters:
nThreads - the number of threads in the pool
Parameters:
threadFactory - the factory to use when creating new threads the newly created thread pool
throws:
NullPointerException - if threadFactory is null
throws:
IllegalArgumentException - if nThreads <= 0 |
| newScheduledThreadPool | | public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize)(Code) | | Creates a thread pool that can schedule commands to run after a
given delay, or to execute periodically.
Parameters:
corePoolSize - the number of threads to keep in the pool,even if they are idle. a newly created scheduled thread pool
throws:
IllegalArgumentException - if corePoolSize < 0 |
| newScheduledThreadPool | | public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize, ThreadFactory threadFactory)(Code) | | Creates a thread pool that can schedule commands to run after a
given delay, or to execute periodically.
Parameters:
corePoolSize - the number of threads to keep in the pool,even if they are idle.
Parameters:
threadFactory - the factory to use when the executorcreates a new thread. a newly created scheduled thread pool
throws:
IllegalArgumentException - if corePoolSize < 0
throws:
NullPointerException - if threadFactory is null |
| newSingleThreadExecutor | | public static ExecutorService newSingleThreadExecutor()(Code) | | Creates an Executor that uses a single worker thread operating
off an unbounded queue. (Note however that if this single
thread terminates due to a failure during execution prior to
shutdown, a new one will take its place if needed to execute
subsequent tasks.) Tasks are guaranteed to execute
sequentially, and no more than one task will be active at any
given time. Unlike the otherwise equivalent
newFixedThreadPool(1) the returned executor is
guaranteed not to be reconfigurable to use additional threads.
the newly created single-threaded Executor |
| newSingleThreadExecutor | | public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory)(Code) | | Creates an Executor that uses a single worker thread operating
off an unbounded queue, and uses the provided ThreadFactory to
create a new thread when needed. Unlike the otherwise
equivalent newFixedThreadPool(1, threadFactory) the
returned executor is guaranteed not to be reconfigurable to use
additional threads.
Parameters:
threadFactory - the factory to use when creating newthreads the newly created single-threaded Executor
throws:
NullPointerException - if threadFactory is null |
| newSingleThreadScheduledExecutor | | public static ScheduledExecutorService newSingleThreadScheduledExecutor()(Code) | | Creates a single-threaded executor that can schedule commands
to run after a given delay, or to execute periodically.
(Note however that if this single
thread terminates due to a failure during execution prior to
shutdown, a new one will take its place if needed to execute
subsequent tasks.) Tasks are guaranteed to execute
sequentially, and no more than one task will be active at any
given time. Unlike the otherwise equivalent
newScheduledThreadPool(1) the returned executor is
guaranteed not to be reconfigurable to use additional threads.
the newly created scheduled executor |
| newSingleThreadScheduledExecutor | | public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory)(Code) | | Creates a single-threaded executor that can schedule commands
to run after a given delay, or to execute periodically. (Note
however that if this single thread terminates due to a failure
during execution prior to shutdown, a new one will take its
place if needed to execute subsequent tasks.) Tasks are
guaranteed to execute sequentially, and no more than one task
will be active at any given time. Unlike the otherwise
equivalent newScheduledThreadPool(1, threadFactory)
the returned executor is guaranteed not to be reconfigurable to
use additional threads.
Parameters:
threadFactory - the factory to use when creating newthreads a newly created scheduled executor
throws:
NullPointerException - if threadFactory is null |
| privilegedCallable | | public static Callable<T> privilegedCallable(Callable<T> callable)(Code) | | Returns a
Callable object that will, when
called, execute the given callable under the current
access control context. This method should normally be
invoked within an
AccessController.doPrivileged action
to create callables that will, if possible, execute under the
selected permission settings holding within that action; or if
not possible, throw an associated
AccessControlException .
Parameters:
callable - the underlying task a callable object
throws:
NullPointerException - if callable null |
| privilegedCallableUsingCurrentClassLoader | | public static Callable<T> privilegedCallableUsingCurrentClassLoader(Callable<T> callable)(Code) | | Returns a
Callable object that will, when
called, execute the given callable under the current
access control context, with the current context class loader
as the context class loader. This method should normally be
invoked within an
AccessController.doPrivileged action
to create callables that will, if possible, execute under the
selected permission settings holding within that action; or if
not possible, throw an associated
AccessControlException .
Parameters:
callable - the underlying task a callable object
throws:
NullPointerException - if callable null
throws:
AccessControlException - if the current access controlcontext does not have permission to both set and get contextclass loader. |
| privilegedThreadFactory | | public static ThreadFactory privilegedThreadFactory()(Code) | | Returns a thread factory used to create new threads that
have the same permissions as the current thread.
This factory creates threads with the same settings as
Executors.defaultThreadFactory , additionally setting the
AccessControlContext and contextClassLoader of new threads to
be the same as the thread invoking this
privilegedThreadFactory method. A new
privilegedThreadFactory can be created within an
AccessController.doPrivileged action setting the
current thread's access control context to create threads with
the selected permission settings holding within that action.
Note that while tasks running within such threads will have
the same access control and class loader settings as the
current thread, they need not have the same
java.lang.ThreadLocal or
java.lang.InheritableThreadLocal values. If necessary,
particular values of thread locals can be set or reset before
any task runs in
ThreadPoolExecutor subclasses using
ThreadPoolExecutor.beforeExecute . Also, if it is
necessary to initialize worker threads to have the same
InheritableThreadLocal settings as some other designated
thread, you can create a custom ThreadFactory in which that
thread waits for and services requests to create others that
will inherit its values.
a thread factory
throws:
AccessControlException - if the current access controlcontext does not have permission to both get and set contextclass loader. |
| unconfigurableExecutorService | | public static ExecutorService unconfigurableExecutorService(ExecutorService executor)(Code) | | Returns an object that delegates all defined
ExecutorService methods to the given executor, but not any
other methods that might otherwise be accessible using
casts. This provides a way to safely "freeze" configuration and
disallow tuning of a given concrete implementation.
Parameters:
executor - the underlying implementation an ExecutorService instance
throws:
NullPointerException - if executor null |
| unconfigurableScheduledExecutorService | | public static ScheduledExecutorService unconfigurableScheduledExecutorService(ScheduledExecutorService executor)(Code) | | Returns an object that delegates all defined
ScheduledExecutorService methods to the given executor, but
not any other methods that might otherwise be accessible using
casts. This provides a way to safely "freeze" configuration and
disallow tuning of a given concrete implementation.
Parameters:
executor - the underlying implementation a ScheduledExecutorService instance
throws:
NullPointerException - if executor null |
|
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