Class ReferenceMap<K,V> 
- Type Parameters:
- K- the type of the keys in the map
- V- the type of the values in the map
- All Implemented Interfaces:
- Serializable,- Map<K,,- V> - Get<K,,- V> - IterableGet<K,,- V> - IterableMap<K,,- V> - Put<K,- V> 
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 collector removing entries.
 
 All the available iterators can be reset back to the start by casting to
 ResettableIterator and calling reset().
 
 Note that ReferenceMap is not synchronized and is not thread-safe.
 If you wish to use this map from multiple threads concurrently, you must use
 appropriate synchronization. The simplest approach is to wrap this map
 using Collections.synchronizedMap(java.util.Map<K, V>). This class may throw
 exceptions when accessed by concurrent threads without synchronization.
 
 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.
 
- Since:
- 3.0 (previously in main package v2.1)
- See Also:
- 
Nested Class SummaryNested classes/interfaces inherited from class org.apache.commons.collections4.map.AbstractReferenceMapAbstractReferenceMap.ReferenceEntry<K,V>, AbstractReferenceMap.ReferenceStrength Nested classes/interfaces inherited from class org.apache.commons.collections4.map.AbstractHashedMapAbstractHashedMap.EntrySet<K,V>, AbstractHashedMap.EntrySetIterator<K, V>, AbstractHashedMap.HashEntry<K, V>, AbstractHashedMap.HashIterator<K, V>, AbstractHashedMap.HashMapIterator<K, V>, AbstractHashedMap.KeySet<K>, AbstractHashedMap.KeySetIterator<K>, AbstractHashedMap.Values<V>, AbstractHashedMap.ValuesIterator<V> Nested classes/interfaces inherited from class java.util.AbstractMapAbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K, V> 
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Field SummaryFields inherited from class org.apache.commons.collections4.map.AbstractHashedMapDEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD, GETKEY_INVALID, GETVALUE_INVALID, MAXIMUM_CAPACITY, NO_NEXT_ENTRY, NO_PREVIOUS_ENTRY, NULL, REMOVE_INVALID, SETVALUE_INVALID
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Constructor SummaryConstructorsConstructorDescriptionConstructs a newReferenceMapthat will use hard references to keys and soft references to values.ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType) Constructs a newReferenceMapthat will use the specified types of references.ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, boolean purgeValues) Constructs a newReferenceMapthat will use the specified types of references.ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor) Constructs a newReferenceMapwith the specified reference types, load factor and initial capacity.ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor, boolean purgeValues) Constructs a newReferenceMapwith the specified reference types, load factor and initial capacity.
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Method SummaryMethods inherited from class org.apache.commons.collections4.map.AbstractReferenceMapclear, containsKey, containsValue, createEntry, createEntrySetIterator, createKeySetIterator, createValuesIterator, doReadObject, doWriteObject, entrySet, get, getEntry, hashEntry, init, isEmpty, isEqualKey, isKeyType, isValueType, keySet, mapIterator, purge, purge, purgeBeforeRead, purgeBeforeWrite, put, remove, size, valuesMethods inherited from class org.apache.commons.collections4.map.AbstractHashedMapaddEntry, addMapping, calculateNewCapacity, calculateThreshold, checkCapacity, clone, convertKey, destroyEntry, ensureCapacity, entryHashCode, entryKey, entryNext, entryValue, equals, hash, hashCode, hashIndex, isEqualValue, putAll, removeEntry, removeMapping, reuseEntry, toString, updateEntryMethods inherited from class java.lang.Objectfinalize, getClass, notify, notifyAll, wait, wait, waitMethods inherited from interface java.util.Mapcompute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
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Constructor Details- 
ReferenceMappublic ReferenceMap()Constructs a newReferenceMapthat will use hard references to keys and soft references to values.
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ReferenceMappublic ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType) Constructs a newReferenceMapthat will use the specified types of references.
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ReferenceMappublic ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, boolean purgeValues) Constructs a newReferenceMapthat will use the specified types of references.
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ReferenceMappublic ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor) Constructs a newReferenceMapwith the specified reference types, load factor and initial capacity.
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ReferenceMappublic ReferenceMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor, boolean purgeValues) Constructs a newReferenceMapwith the specified reference types, load factor and initial capacity.- Parameters:
- keyType- the type of reference to use for keys; must be- HARD,- SOFT,- WEAK
- valueType- the type of reference to use for values; must be- HARD,- SOFT,- WEAK
- capacity- the initial capacity for the map
- loadFactor- the load factor for the map
- purgeValues- should the value be automatically purged when the key is garbage collected
 
 
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