Class ReferenceIdentityMap<K,V> 
- Type Parameters:
- K- the type of the keys in this map
- V- the type of the values in this 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 and matches keys and values based
 on == not equals().
 
 When you construct a ReferenceIdentityMap, 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 default constructor uses hard keys and soft values, providing a memory-sensitive cache.
 This map is similar to
 ReferenceMap.
 It differs in that keys and values in this class are compared using ==.
 
This map will violate the detail of various Map and map view contracts. As a general rule, don't compare this map to other maps.
 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 ReferenceIdentityMap.
 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 ReferenceIdentityMap 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.
 
- 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 newReferenceIdentityMapthat will use hard references to keys and soft references to values.ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType) Constructs a newReferenceIdentityMapthat will use the specified types of references.ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, boolean purgeValues) Constructs a newReferenceIdentityMapthat will use the specified types of references.ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor) Constructs a newReferenceIdentityMapwith the specified reference types, load factor and initial capacity.ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor, boolean purgeValues) Constructs a newReferenceIdentityMapwith the specified reference types, load factor and initial capacity.
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Method SummaryModifier and TypeMethodDescriptionprotected intGets the hash code for the key specified.protected intGets the hash code for a MapEntry.protected booleanisEqualKey(Object key1, Object key2) Compares two keys for equals.protected booleanisEqualValue(Object value1, Object value2) Compares two values for equals.Methods inherited from class org.apache.commons.collections4.map.AbstractReferenceMapclear, containsKey, containsValue, createEntry, createEntrySetIterator, createKeySetIterator, createValuesIterator, doReadObject, doWriteObject, entrySet, get, getEntry, init, isEmpty, 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, hashCode, hashIndex, 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- 
ReferenceIdentityMappublic ReferenceIdentityMap()Constructs a newReferenceIdentityMapthat will use hard references to keys and soft references to values.
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ReferenceIdentityMappublic ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType) Constructs a newReferenceIdentityMapthat will use the specified types of references.
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ReferenceIdentityMappublic ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, boolean purgeValues) Constructs a newReferenceIdentityMapthat will use the specified types of references.
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ReferenceIdentityMappublic ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor) Constructs a newReferenceIdentityMapwith the specified reference types, load factor and initial capacity.
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ReferenceIdentityMappublic ReferenceIdentityMap(AbstractReferenceMap.ReferenceStrength keyType, AbstractReferenceMap.ReferenceStrength valueType, int capacity, float loadFactor, boolean purgeValues) Constructs a newReferenceIdentityMapwith 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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Method Details- 
hash
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hashEntryGets the hash code for a MapEntry.This implementation uses the identity hash code. - Overrides:
- hashEntryin class- AbstractReferenceMap<K,- V> 
- Parameters:
- key- the key to get a hash code for, may be null
- value- the value to get a hash code for, may be null
- Returns:
- the hash code, as per the MapEntry specification
 
- 
isEqualKeyCompares two keys for equals.This implementation converts the key from the entry to a real reference before comparison and uses ==.- Overrides:
- isEqualKeyin class- AbstractReferenceMap<K,- V> 
- Parameters:
- key1- the first key to compare passed in from outside
- key2- the second key extracted from the entry via- entry.key
- Returns:
- true if equal by identity
 
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isEqualValueCompares two values for equals.This implementation uses ==.- Overrides:
- isEqualValuein class- AbstractHashedMap<K,- V> 
- Parameters:
- value1- the first value to compare passed in from outside
- value2- the second value extracted from the entry via- getValue()
- Returns:
- true if equal by identity
 
 
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