Package edu.uiuc.ncsa.security.core.util

Class DoubleHashMap<K,V>

java.lang.Object

edu.uiuc.ncsa.security.core.util.DoubleHashMap<K,V>

All Implemented Interfaces:

Serializable, Map<K,V>

public class DoubleHashMap<K,V>
extends Object
implements Map<K,V>, Serializable

A hashmap with two-way lookup. This maintains a second hashmap that has the keys reversed. Access these elements with getByValue(Object). There are some caveats. For one thing, this assumes that there is a one to one correspondence between keys and values so this specifically dis-allows null objects as values. Multiple values will get over-written. with "predictable but unwanted results."

Created by Jeff Gaynor
on 3/1/12 at 2:06 PM

See Also:

Serialized Form

Nested Class Summary

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

Map.Entry<K extends Object,V extends Object>

Constructor Summary

Constructors

Constructor	Description
DoubleHashMap()

Method Summary

Modifier and Type	Method	Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<K,V>>	entrySet()
V	get(Object key)
K	getByValue(V value)
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value)
void	putAll(Map<? extends K,? extends V> m)	Slow since this loops.
V	remove(Object key)
int	size()
Collection<V>	values()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Map

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

Constructor Detail

DoubleHashMap

public DoubleHashMap()

Method Detail

clear

public void clear()

Specified by:

clear in interface Map<K,V>

size

public int size()

Specified by:

size in interface Map<K,V>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

containsKey

public boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

get

public V get(Object key)

Specified by:

get in interface Map<K,V>

put

public V put(K key,
             V value)

Specified by:

put in interface Map<K,V>

remove

public V remove(Object key)

Specified by:

remove in interface Map<K,V>

putAll

public void putAll(Map<? extends K,? extends V> m)

Slow since this loops. Best to over-ride if you performance is an issue.

Specified by:

putAll in interface Map<K,V>

Parameters:

m -

keySet

public Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

values

public Collection<V> values()

Specified by:

values in interface Map<K,V>

entrySet

public Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

getByValue

public K getByValue(V value)