public interface ScheduledExecutorService extends ExecutorService
ExecutorService that can schedule commands to run after a given
delay, or to execute periodically.
The schedule methods create tasks with various delays and return a task object that can be used to cancel or check execution. The scheduleAtFixedRate and scheduleWithFixedDelay methods create and execute tasks that run periodically until cancelled.
Commands submitted using the Executor.execute(java.lang.Runnable) and
ExecutorService submit methods are scheduled with
a requested delay of zero. Zero and negative delays (but not
periods) are also allowed in schedule methods, and are
treated as requests for immediate execution.
All schedule methods accept relative delays and
periods as arguments, not absolute times or dates. It is a simple
matter to transform an absolute time represented as a Date to the required form. For example, to schedule at
a certain future date, you can use: schedule(task,
date.getTime() - System.currentTimeMillis(),
TimeUnit.MILLISECONDS). Beware however that expiration of a
relative delay need not coincide with the current Date at
which the task is enabled due to network time synchronization
protocols, clock drift, or other factors.
The Executors class provides convenient factory methods for
the ScheduledExecutorService implementations provided in this package.
import static java.util.concurrent.TimeUnit.*;
class BeeperControl {
private final ScheduledExecutorService scheduler =
Executors.newScheduledThreadPool(1);
public void beepForAnHour() {
final Runnable beeper = new Runnable() {
public void run() { System.out.println("beep"); }
};
final ScheduledFuture<?> beeperHandle =
scheduler.scheduleAtFixedRate(beeper, 10, 10, SECONDS);
scheduler.schedule(new Runnable() {
public void run() { beeperHandle.cancel(true); }
}, 60 * 60, SECONDS);
}
}| Modifier and Type | Method and Description |
|---|---|
<V> ScheduledFuture<V> |
schedule(Callable<V> callable,
long delay,
TimeUnit unit)
Creates and executes a ScheduledFuture that becomes enabled after the
given delay.
|
ScheduledFuture<?> |
schedule(Runnable command,
long delay,
TimeUnit unit)
Creates and executes a one-shot action that becomes enabled
after the given delay.
|
ScheduledFuture<?> |
scheduleAtFixedRate(Runnable command,
long initialDelay,
long period,
TimeUnit unit)
Creates and executes a periodic action that becomes enabled first
after the given initial delay, and subsequently with the given
period; that is executions will commence after
initialDelay then initialDelay+period, then
initialDelay + 2 * period, and so on.
|
ScheduledFuture<?> |
scheduleWithFixedDelay(Runnable command,
long initialDelay,
long delay,
TimeUnit unit)
Creates and executes a periodic action that becomes enabled first
after the given initial delay, and subsequently with the
given delay between the termination of one execution and the
commencement of the next.
|
awaitTermination, invokeAll, invokeAll, invokeAny, invokeAny, isShutdown, isTerminated, shutdown, shutdownNow, submit, submit, submitScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit)
command - the task to executedelay - the time from now to delay executionunit - the time unit of the delay parameterRejectedExecutionException - if the task cannot be
scheduled for executionNullPointerException - if command is null<V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit)
callable - the function to executedelay - the time from now to delay executionunit - the time unit of the delay parameterRejectedExecutionException - if the task cannot be
scheduled for executionNullPointerException - if callable is nullScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit)
command - the task to executeinitialDelay - the time to delay first executionperiod - the period between successive executionsunit - the time unit of the initialDelay and period parametersRejectedExecutionException - if the task cannot be
scheduled for executionNullPointerException - if command is nullIllegalArgumentException - if period less than or equal to zeroScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit)
command - the task to executeinitialDelay - the time to delay first executiondelay - the delay between the termination of one
execution and the commencement of the nextunit - the time unit of the initialDelay and delay parametersRejectedExecutionException - if the task cannot be
scheduled for executionNullPointerException - if command is nullIllegalArgumentException - if delay less than or equal to zero Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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