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Copyright © 2006 Sun Microsystems, Inc. All rights reserved.

javax.tv.util
Class TVTimer

java.lang.Object
  javax.tv.util.TVTimer

public abstract class TVTimer

extends java.lang.Object

A class representing a timer. A timer is responsible for managing a set of timer events specified by timer specifications. When the timer event should be sent, the timer calls the timer specification's notifyListeners() method.

See Also:

TVTimerSpec

Constructor Summary

TVTimer()
Constructs a TVTimer object.

Method Summary

abstract void	deschedule(TVTimerSpec t) Removes a timer specification from the set of monitored specifications.
abstract long	getGranularity() Report the granularity of this timer, i.e., the length of time between "ticks" of this timer.
abstract long	getMinRepeatInterval() Report the minimum interval that this timer can repeat tasks.
static TVTimer	getTimer() Returns the default timer for the system.
abstract TVTimerSpec	scheduleTimerSpec(TVTimerSpec t) Begins monitoring a TVTimerSpec.

Methods inherited from class java.lang.Object

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

Constructor Detail

TVTimer

public TVTimer()

Constructs a TVTimer object.

Method Detail

getTimer

public static TVTimer getTimer()

Returns the default timer for the system. There may be one TVTimer instance per virtual machine, one per applet, one per call to getTimer(), or some other platform dependent implementation.

Returns:

A non-null TVTimer object.

scheduleTimerSpec

public abstract TVTimerSpec scheduleTimerSpec(TVTimerSpec t)
                                       throws TVTimerScheduleFailedException

Begins monitoring a TVTimerSpec.

When the timer specification should go off, the timer will call TVTimerSpec.notifyListeners().

Returns the actual TVTimerSpec that got scheduled. If you schedule a specification that implies a smaller granularity than this timer can provide, or a repeat timer specification that has a smaller repeating interval than this timer can provide, the timer should round to the closest value and return that value as a TVTimerSpec object. An interested application can use accessor methods getMinRepeatInterval() and getGranularity() to obtain the Timer's best knowledge of the Timer's limitation on granularity and repeat interval.

If you schedule an absolute specification that should have gone off already, it will be scheduled to go off immediately, and the return value of this method will be an absolute specification reflecting the current time. The actual listener notification may happen asynchronously.

If the scheduled specification cannot be satisfied, the exception TVTimerScheduleFailedException should be thrown.

You may schedule a timer specification with multiple timers. You may schedule a timer specification with the same timer multiple times (in which case it will go off multiple times). If you modify a timer specification after it has been scheduled with any timer, the results are unspecified.

Note: The specified TimerSpec object may be modified by this method, e.g., a delayed TimerSpec may be transformed into an absolute TimerSpec.

Parameters:

t - The timer specification to begin monitoring.

Returns:

The real TVTimerSpec that was scheduled.

Throws:

TVTimerScheduleFailedException - is thrown when the scheduled specification cannot be satisfied.

deschedule

public abstract void deschedule(TVTimerSpec t)

Removes a timer specification from the set of monitored specifications. The descheduling happens as soon as practical, but may not happen immediately. If the timer specification has been scheduled multiple times with this timer, all the schedulings are canceled. No other instances of timer specifications shall be descheduled.

The specified TVTimerSpec instance t must be an instance previously passed into the method scheduleTimerSpec on the same instance of TVTimer. If it is not, no action is performed.

Parameters:

t - The timer specification to end monitoring.

getMinRepeatInterval

public abstract long getMinRepeatInterval()

Report the minimum interval that this timer can repeat tasks. For example, it's perfectly reasonable for a Timer to specify that the minimum interval for a repeatedly performed task is 1000 milliseconds between every run. This is to avoid possible system overloading.

Returns:

The timer's best knowledge of minimum repeat interval in milliseconds. Return -1 if this timer doesn't know its repeating interval limitation.

getGranularity

public abstract long getGranularity()

Report the granularity of this timer, i.e., the length of time between "ticks" of this timer.

Returns:

The timer's best knowledge of the granularity in milliseconds. Return -1 if this timer doesn't know its granularity.