Class WeakReferenceContainer
java.lang.Object
org.castor.cache.hashbelt.container.WeakReferenceContainer
An implementation of a container that uses weak references for storing values
in the map, so that values can be removed from the map by the system when the
system is under memory pressure. Keys, however, are kept strong - so contains()
may well find an element, but the value may have been lost. Make sure you test
for null returns from put.
Note that keys are hard references; in a situation where OutOfMemory will occur, the JVM will first wipe out all unreferenced objects whose only link is a weak reference. An out of memory will wipe all values from the maps which are currently unreferenced. The keys remain until the hashbelt containers are garbage collected, an put is called with that key or when the value should be accessed through any operation of the Container interface.
- Since:
- 1.0
- Version:
- $Revision: 8102 $ $Date: 2006-04-25 16:09:10 -0600 (Tue, 25 Apr 2006) $
- Author:
- Gregory Block, Ralf Joachim
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Nested Class Summary
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
clear()
boolean
containsKey
(Object key) boolean
containsValue
(Object value) entrySet()
long
Returns the timestamp of this container.boolean
isEmpty()
Returns an iterator over the keys contained in this container.keySet()
void
int
size()
void
Set the timestamp of this container to System.currentTimeMillis().Returns an iterator over the values contained in this container.values()
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, merge, putIfAbsent, remove, replace, replace, replaceAll
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Constructor Details
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WeakReferenceContainer
public WeakReferenceContainer()
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Method Details
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updateTimestamp
public void updateTimestamp()Set the timestamp of this container to System.currentTimeMillis().- Specified by:
updateTimestamp
in interfaceContainer
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getTimestamp
public long getTimestamp()Returns the timestamp of this container.- Specified by:
getTimestamp
in interfaceContainer
- Returns:
- The timestamp.
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keyIterator
Returns an iterator over the keys contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.- Specified by:
keyIterator
in interfaceContainer
- Returns:
- An iterator over the keys currently contained in the container.
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valueIterator
Returns an iterator over the values contained in this container. If the container is modified while an iteration is in progress, the results of the iteration is not affected and vice-versa.- Specified by:
valueIterator
in interfaceContainer
- Returns:
- An iterator over the values currently contained in the container.
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size
public int size() -
isEmpty
public boolean isEmpty() -
containsKey
- Specified by:
containsKey
in interfaceMap<Object,
Object>
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containsValue
- Specified by:
containsValue
in interfaceMap<Object,
Object>
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get
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put
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remove
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putAll
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clear
public void clear() -
keySet
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values
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entrySet
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