Package name.pachler.nio.file
Class WatchKey
- java.lang.Object
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- name.pachler.nio.file.WatchKey
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- Direct Known Subclasses:
PathWatchKey
public abstract class WatchKey extends java.lang.Object
AWatchKey
represents aWatchable
's registration for events with aWatchService
. It is created on registration and subsequently used to retreiveWatchEvent
s.
To stop receiving events from aWatchService
(that is, undoing registration), use thecancel()
method. Note that this will invalidate theWatchKey
, which should then be discarded (as it cannot be reused).- See Also:
WatchService.poll()
,WatchService.take()
,pollEvents()
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Constructor Summary
Constructors Modifier Constructor Description protected
WatchKey()
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description abstract void
cancel()
This cancels the registration with the WatchService that this WatchKey was registered with.abstract boolean
isValid()
abstract java.util.List<WatchEvent<?>>
pollEvents()
Returns the events that have occurred for this WatchKey.abstract boolean
reset()
Resets thisWatchKey
(marks it as non-signalled) so that it's correspondingWatchService
can report it again via it'sWatchService.poll()
andWatchService.take()
methods.
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Method Detail
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cancel
public abstract void cancel()
This cancels the registration with the WatchService that this WatchKey was registered with. This means that no new events will be delivered to this key any more. Events that are pending can still be retreived with pollEvents(), and if the WatchKey is still marked as signalled a call to WatchService's poll() or take() functions will still return it.
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isValid
public abstract boolean isValid()
- Returns:
- if this watch key is valid. A watch key is valid if
- It has not been canceled
- The WatchService is not yet closed
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pollEvents
public abstract java.util.List<WatchEvent<?>> pollEvents()
Returns the events that have occurred for this WatchKey. Just calling this method will not reset the signalled state of this key; you'll have to call #reset() to indicate to the WatchService that the the client is ready to receive more events and that the key can be re-queued. After the WatchService has determined that events have occurred for a registered Watchable represented by a given WatchKey, it will return that key when the client calls it's WatchService#take() or WatchService#poll() methods.- Returns:
- a list of events that have occurred since the last time that #pollEvents() was called.
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reset
public abstract boolean reset()
Resets thisWatchKey
(marks it as non-signalled) so that it's correspondingWatchService
can report it again via it'sWatchService.poll()
andWatchService.take()
methods.- Returns:
true
if the key could be reset,false
otherwise (typically if the correspondingWatchService
has been closed or if the the key was not signalled).
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