public class ReferenceMap<K,V> extends AbstractReferenceMap<K,V> implements Serializable
Map implementation that allows mappings to be removed by the
garbage collector.
When you construct a ReferenceMap, you can specify what kind of
references are used to store the map's keys and values. If non-hard
references are used, then the garbage collector can remove mappings if a key
or value becomes unreachable, or if the JVM's memory is running low. For
information on how the different reference types behave, see
Reference.
Different types of references can be specified for keys and values. The keys
can be configured to be weak but the values hard, in which case this class
will behave like a
WeakHashMap. However, you can also specify hard keys and
weak values, or any other combination. The default constructor uses hard keys
and soft values, providing a memory-sensitive cache.
This map is similar to ReferenceIdentityMap. It differs in that keys and
values in this class are compared using equals().
This Map implementation does not allow null
elements. Attempting to add a null key or value to the map will raise a
NullPointerException.
This implementation is not synchronized. You can use
Collections.synchronizedMap(java.util.Map<K, V>) to provide synchronized access
to a ReferenceMap. Remember that synchronization will not stop
the garbage collecter removing entries.
All the available iterators can be reset back to the start by casting to
ResettableIterator and calling reset().
NOTE: As from Commons Collections 3.1 this map extends
AbstractReferenceMap (previously it extended AbstractMap). As a
result, the implementation is now extensible and provides a
MapIterator.Reference,
Serialized FormAbstractReferenceMap.ReferenceEntry<K,V>AbstractHashedMap.EntrySet<K,V>, AbstractHashedMap.EntrySetIterator<K,V>, AbstractHashedMap.HashEntry<K,V>, AbstractHashedMap.HashIterator<K,V>, AbstractHashedMap.HashMapIterator<K,V>, AbstractHashedMap.KeySet<K,V>, AbstractHashedMap.KeySetIterator<K,V>, AbstractHashedMap.Values<K,V>, AbstractHashedMap.ValuesIterator<K,V>AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>HARD, keyType, purgeValues, SOFT, valueType, WEAKdata, DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD, entrySet, GETKEY_INVALID, GETVALUE_INVALID, keySet, loadFactor, MAXIMUM_CAPACITY, modCount, NO_NEXT_ENTRY, NO_PREVIOUS_ENTRY, NULL, REMOVE_INVALID, SETVALUE_INVALID, size, threshold, values| Constructor and Description |
|---|
ReferenceMap()
Constructs a new
ReferenceMap that will use hard references
to keys and soft references to values. |
ReferenceMap(int keyType,
int valueType)
Constructs a new
ReferenceMap that will use the specified
types of references. |
ReferenceMap(int keyType,
int valueType,
boolean purgeValues)
Constructs a new
ReferenceMap that will use the specified
types of references. |
ReferenceMap(int keyType,
int valueType,
int capacity,
float loadFactor)
Constructs a new
ReferenceMap with the specified reference
types, load factor and initial capacity. |
ReferenceMap(int keyType,
int valueType,
int capacity,
float loadFactor,
boolean purgeValues)
Constructs a new
ReferenceMap with the specified reference
types, load factor and initial capacity. |
clear, containsKey, containsValue, createEntry, createEntrySetIterator, createKeySetIterator, createValuesIterator, doReadObject, doWriteObject, entrySet, get, getEntry, hashEntry, init, isEmpty, isEqualKey, keySet, mapIterator, purge, purge, purgeBeforeRead, purgeBeforeWrite, put, remove, size, valuesaddEntry, addMapping, calculateNewCapacity, calculateThreshold, checkCapacity, clone, destroyEntry, ensureCapacity, entryHashCode, entryKey, entryNext, entryValue, equals, hash, hashCode, hashIndex, isEqualValue, putAll, removeEntry, removeMapping, reuseEntry, toString, updateEntrypublic ReferenceMap()
ReferenceMap that will use hard references
to keys and soft references to values.public ReferenceMap(int keyType,
int valueType)
ReferenceMap that will use the specified
types of references.keyType - the type of reference to use for keys; must be AbstractReferenceMap.HARD,
AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKvalueType - the type of reference to use for values; must be AbstractReferenceMap.HARD
, AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKpublic ReferenceMap(int keyType,
int valueType,
boolean purgeValues)
ReferenceMap that will use the specified
types of references.keyType - the type of reference to use for keys; must be AbstractReferenceMap.HARD,
AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKvalueType - the type of reference to use for values; must be AbstractReferenceMap.HARD
, AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKpurgeValues - should the value be automatically purged when the key is
garbage collectedpublic ReferenceMap(int keyType,
int valueType,
int capacity,
float loadFactor)
ReferenceMap with the specified reference
types, load factor and initial capacity.keyType - the type of reference to use for keys; must be AbstractReferenceMap.HARD,
AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKvalueType - the type of reference to use for values; must be AbstractReferenceMap.HARD
, AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKcapacity - the initial capacity for the maploadFactor - the load factor for the mappublic ReferenceMap(int keyType,
int valueType,
int capacity,
float loadFactor,
boolean purgeValues)
ReferenceMap with the specified reference
types, load factor and initial capacity.keyType - the type of reference to use for keys; must be AbstractReferenceMap.HARD,
AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKvalueType - the type of reference to use for values; must be AbstractReferenceMap.HARD
, AbstractReferenceMap.SOFT, AbstractReferenceMap.WEAKcapacity - the initial capacity for the maploadFactor - the load factor for the mappurgeValues - should the value be automatically purged when the key is
garbage collectedCopyright © 2014. All Rights Reserved.