edu.ucla.sspace.util

Class CharMap<V>

java.lang.Object

java.util.AbstractMap<Character,V>

edu.ucla.sspace.util.CharMap<V>

All Implemented Interfaces:

Serializable, Map<Character,V>

public class CharMap<V>
extends AbstractMap<Character,V>
implements Serializable

A space-optimized map for associating char keys with values.

This class makes a trade off for reduced space usage at the cost of decreased performace. The put, get, containsKey and get operations are all logarithmic when the map is unmodified. If a new mapping is added, or one is removed, the operation is linear in the number of mappings. Both size and isEmpty are still constant time.

The get operation runs in logarithmic time. The set operation runs in consant time if setting an existing non-zero value to a non-zero value. However, if the set invocation sets a zero value to non-zero, the operation is linear with the size of the array.

This map allows null values.

Iteration ordering follows the natural ordering of char values, with the lowest char key value being returned first. Implementation Note: the Iterator.remove() method is currently unsupported and will throw an exception when called. However, a future implementation will fix this.

Author:

David Jurgens

See Also:

TrieMap, IntegerMap, Map, Serialized Form

Nested Class Summary

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

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

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

Map.Entry<K,V>

Constructor Summary

Constructors

Constructor and Description
CharMap() Creates a new map.
CharMap(Map<Character,? extends V> m) Creates a new map with the mappings contained in m.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Removes all of the mappings from this map.
boolean	containsKey(Object key) Returns true if this map contains a mapping for the specified key.
boolean	containsValue(Object value)
Set<Map.Entry<Character,V>>	entrySet() Returns a Set view of the mappings contained in this map.
V	get(char key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
V	get(Object key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
Set<Character>	keySet() Returns a Set view of the keys contained in this map.
V	put(Character key, V value) Adds the mapping from the provided key to the value.
V	put(char key, V value) Adds the mapping from the provided key to the value.
V	remove(char key) Removes the mapping for a key from this map if it is present and returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.
V	remove(Object key) Removes the mapping for a key from this map if it is present and returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.
int	size() Returns the number of key-value mappings in this trie.
Collection<V>	values() Returns a Collection view of the values contained in this map.

Methods inherited from class java.util.AbstractMap

clone, equals, hashCode, isEmpty, putAll, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CharMap

public CharMap()

Creates a new map.

CharMap

public CharMap(Map<Character,? extends V> m)

Creates a new map with the mappings contained in m.

Method Detail

clear

public void clear()

Removes all of the mappings from this map.

Specified by:

clear in interface Map<Character,V>

Overrides:

clear in class AbstractMap<Character,V>

containsKey

public boolean containsKey(Object key)

Returns true if this map contains a mapping for the specified key.

Specified by:

containsKey in interface Map<Character,V>

Overrides:

containsKey in class AbstractMap<Character,V>

containsValue

public boolean containsValue(Object value)

Specified by:

containsValue in interface Map<Character,V>

Overrides:

containsValue in class AbstractMap<Character,V>

entrySet

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

Returns a Set view of the mappings contained in this map.

Specified by:

entrySet in interface Map<Character,V>

Specified by:

entrySet in class AbstractMap<Character,V>

get

public V get(Object key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

Specified by:

get in interface Map<Character,V>

Overrides:

get in class AbstractMap<Character,V>

get

public V get(char key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

keySet

public Set<Character> keySet()

Returns a Set view of the keys contained in this map.

Specified by:

keySet in interface Map<Character,V>

Overrides:

keySet in class AbstractMap<Character,V>

put

public V put(Character key,
    V value)

Adds the mapping from the provided key to the value.

Specified by:

put in interface Map<Character,V>

Overrides:

put in class AbstractMap<Character,V>

Parameters:

key -

value -

Throws:

NullPointerException - if the key is null

IllegalArgumentException - if the key is not an instance of Integer

put

public V put(char key,
    V value)

Adds the mapping from the provided key to the value.

Parameters:

key -

value -

Throws:

NullPointerException - if the key is null

IllegalArgumentException - if the key is not an instance of Integer

remove

public V remove(Object key)

Removes the mapping for a key from this map if it is present and returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.

Specified by:

remove in interface Map<Character,V>

Overrides:

remove in class AbstractMap<Character,V>

Parameters:

key - key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key.

remove

public V remove(char key)

Removes the mapping for a key from this map if it is present and returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.

Parameters:

key - key whose mapping is to be removed from the map

Returns:

the previous value associated with key, or null if there was no mapping for key.

size

public int size()

Returns the number of key-value mappings in this trie.

Specified by:

size in interface Map<Character,V>

Overrides:

size in class AbstractMap<Character,V>

values

public Collection<V> values()

Returns a Collection view of the values contained in this map.

Specified by:

values in interface Map<Character,V>

Overrides:

values in class AbstractMap<Character,V>