org.apache.commons.collections.map

Class IdentityMap

java.lang.Object

java.util.AbstractMap

org.apache.commons.collections.map.AbstractHashedMap

org.apache.commons.collections.map.IdentityMap

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.util.Map, IterableMap

public class IdentityMap
extends AbstractHashedMap
implements java.io.Serializable, java.lang.Cloneable

A Map implementation that matches keys and values based on == not equals().

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.

Note that IdentityMap 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(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

Since:

Commons Collections 3.0

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
IdentityMap() Constructs a new empty map with default size and load factor.
IdentityMap(int initialCapacity) Constructs a new, empty map with the specified initial capacity.
IdentityMap(int initialCapacity, float loadFactor) Constructs a new, empty map with the specified initial capacity and load factor.
IdentityMap(java.util.Map map) Constructor copying elements from another map.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone() Clones the map without cloning the keys or values.

Methods inherited from class org.apache.commons.collections.map.AbstractHashedMap

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, mapIterator, put, putAll, remove, size, toString, values

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll

Constructor Detail

IdentityMap

public IdentityMap()

Constructs a new empty map with default size and load factor.

IdentityMap

public IdentityMap(int initialCapacity)

Constructs a new, empty map with the specified initial capacity.

Parameters:

initialCapacity - the initial capacity

Throws:

java.lang.IllegalArgumentException - if the initial capacity is less than one

IdentityMap

public IdentityMap(int initialCapacity,
                   float loadFactor)

Constructs a new, empty map with the specified initial capacity and load factor.

Parameters:

initialCapacity - the initial capacity

loadFactor - the load factor

Throws:

java.lang.IllegalArgumentException - if the initial capacity is less than one

java.lang.IllegalArgumentException - if the load factor is less than zero

IdentityMap

public IdentityMap(java.util.Map map)

Constructor copying elements from another map.

Parameters:

map - the map to copy

Throws:

java.lang.NullPointerException - if the map is null

Method Detail

clone

public java.lang.Object clone()

Clones the map without cloning the keys or values.

Returns:

a shallow clone