gw.util

Class SpaceEfficientHashMap<K,V>

java.lang.Object

gw.util.SpaceEfficientHashMap<K,V>

All Implemented Interfaces:

Map<K,V>

public class SpaceEfficientHashMap<K,V>
extends Object
implements Map<K,V>

Nested Class Summary

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
SpaceEfficientHashMap()
SpaceEfficientHashMap(Map<? extends K,? extends V> m) Constructs a new HashMap with the same mappings as the specified Map.

Method Summary

Modifier and Type	Method and Description
void	clear()
boolean	containsKey(Object key)
boolean	containsValue(Object value)
Set<Map.Entry<K,V>>	entrySet()
boolean	equals(Object o) Compares the specified object with this map for equality.
V	get(Object key)
int	hashCode() Returns the hash code value for this map.
boolean	isEmpty()
Set<K>	keySet()
V	put(K key, V value)
void	putAll(Map<? extends K,? extends V> m)
V	remove(Object key)
int	size()
String	toString()
void	trimToSize()
Collection<V>	values()

Methods inherited from class java.lang.Object

clone, finalize, 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

SpaceEfficientHashMap

public SpaceEfficientHashMap()

SpaceEfficientHashMap

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

Constructs a new HashMap with the same mappings as the specified Map. The HashMap is created with default load factor (0.75) and an initial capacity sufficient to hold the mappings in the specified Map.

Parameters:

m - the map whose mappings are to be placed in this map

Throws:

NullPointerException - if the specified map is null

Method Detail

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)

Specified by:

putAll in interface Map<K,V>

clear

public void clear()

Specified by:

clear in interface Map<K,V>

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>

equals

public boolean equals(Object o)

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This ensures that the equals method works properly across different implementations of the Map interface.

This implementation first checks if the specified object is this map; if so it returns true. Then, it checks if the specified object is a map whose size is identical to the size of this map; if not, it returns false. If so, it iterates over this map's entrySet collection, and checks that the specified map contains each mapping that this map contains. If the specified map fails to contain such a mapping, false is returned. If the iteration completes, true is returned.

Specified by:

equals in interface Map<K,V>

Overrides:

equals in class Object

Parameters:

o - object to be compared for equality with this map

Returns:

true if the specified object is equal to this map

hashCode

public int hashCode()

Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hash codes of each entry in the map's entrySet() view. This ensures that m1.equals(m2) implies that m1.hashCode()==m2.hashCode() for any two maps m1 and m2, as required by the general contract of Object.hashCode().

This implementation iterates over entrySet(), calling hashCode() on each element (entry) in the set, and adding up the results.

Specified by:

hashCode in interface Map<K,V>

Overrides:

hashCode in class Object

Returns:

the hash code value for this map

See Also:

Map.Entry#hashCode(), Object.equals(Object), Set.equals(Object)

toString

public String toString()

Overrides:

toString in class Object

trimToSize

public void trimToSize()