org.apache.commons.collections.map
Class IdentityMap<K,V>

java.lang.Object
  extended by java.util.AbstractMap<K,V>
      extended by org.apache.commons.collections.map.AbstractHashedMap<K,V>
          extended by org.apache.commons.collections.map.IdentityMap<K,V>
All Implemented Interfaces:
Serializable, Cloneable, Map<K,V>, IterableMap<K,V>

public class IdentityMap<K,V>
extends AbstractHashedMap<K,V>
implements Serializable, 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.

Since:
Commons Collections 3.0
Version:
$Revision: 1.1.1.1 $ $Date: 2005/05/23 04:35:52 $
Author:
java util HashMap, Matt Hall, John Watkinson, Stephen Colebourne
See Also:
Serialized Form

Nested Class Summary
protected static class IdentityMap.IdentityEntry<K,V>
          HashEntry
 
Nested classes/interfaces inherited from class org.apache.commons.collections.map.AbstractHashedMap
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>
 
Nested classes/interfaces inherited from interface java.util.Map
Map.Entry<K,V>
 
Field Summary
 
Fields inherited from class org.apache.commons.collections.map.AbstractHashedMap
data, 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 Summary
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(Map<? extends K,? extends V> map)
          Constructor copying elements from another map.
 
Method Summary
 Object clone()
          Clones the map without cloning the keys or values.
protected  AbstractHashedMap.HashEntry<K,V> createEntry(AbstractHashedMap.HashEntry<K,V> next, int hashCode, K key, V value)
          Creates an entry to store the data.
protected  int hash(Object key)
          Gets the hash code for the key specified.
protected  boolean isEqualKey(Object key1, Object key2)
          Compares two keys for equals.
protected  boolean isEqualValue(Object value1, Object value2)
          Compares two values for equals.
 
Methods inherited from class org.apache.commons.collections.map.AbstractHashedMap
addEntry, addMapping, calculateNewCapacity, calculateThreshold, checkCapacity, clear, containsKey, containsValue, createEntrySetIterator, createKeySetIterator, createValuesIterator, destroyEntry, doReadObject, doWriteObject, ensureCapacity, entryHashCode, entryKey, entryNext, entrySet, entryValue, equals, get, getEntry, hashCode, hashIndex, init, isEmpty, keySet, mapIterator, put, putAll, remove, removeEntry, removeMapping, reuseEntry, size, toString, updateEntry, values
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

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:
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:
IllegalArgumentException - if the initial capacity is less than one
IllegalArgumentException - if the load factor is less than zero

IdentityMap

public IdentityMap(Map<? extends K,? extends V> map)
Constructor copying elements from another map.

Parameters:
map - the map to copy
Throws:
NullPointerException - if the map is null
Method Detail

hash

protected int hash(Object key)
Gets the hash code for the key specified. This implementation uses the identity hash code.

Overrides:
hash in class AbstractHashedMap<K,V>
Parameters:
key - the key to get a hash code for
Returns:
the hash code

isEqualKey

protected boolean isEqualKey(Object key1,
                             Object key2)
Compares two keys for equals. This implementation uses ==.

Overrides:
isEqualKey in class AbstractHashedMap<K,V>
Parameters:
key1 - the first key to compare
key2 - the second key to compare
Returns:
true if equal by identity

isEqualValue

protected boolean isEqualValue(Object value1,
                               Object value2)
Compares two values for equals. This implementation uses ==.

Overrides:
isEqualValue in class AbstractHashedMap<K,V>
Parameters:
value1 - the first value to compare
value2 - the second value to compare
Returns:
true if equal by identity

createEntry

protected AbstractHashedMap.HashEntry<K,V> createEntry(AbstractHashedMap.HashEntry<K,V> next,
                                                       int hashCode,
                                                       K key,
                                                       V value)
Creates an entry to store the data. This implementation creates an IdentityEntry instance.

Overrides:
createEntry in class AbstractHashedMap<K,V>
Parameters:
next - the next entry in sequence
hashCode - the hash code to use
key - the key to store
value - the value to store
Returns:
the newly created entry

clone

public Object clone()
Clones the map without cloning the keys or values.

Overrides:
clone in class AbstractHashedMap<K,V>
Returns:
a shallow clone


Copyright © 2005-2005 Apache Software Foundation, Matt Hall, John Watkinson. All Rights Reserved.