org.j3d.util
Class CharHashMap

java.lang.Object
  org.j3d.util.CharHashMap

public class CharHashMap
extends java.lang.Object

A hash map that uses primitive chars for the key rather than objects.

Version:

$Revision: 1.1 $

Author:

Justin Couch

See Also:

HashMap

Constructor Summary

CharHashMap()
Constructs a new, empty hashtable with a default capacity and load factor, which is 20 and 0.75 respectively.

CharHashMap(int initialCapacity)
Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.

CharHashMap(int initialCapacity, float loadFactor)
Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.

Method Summary

void	clear() Clears this hashtable so that it contains no keys.
boolean	contains(java.lang.Object value) Tests if some key maps into the specified value in this hashtable.
boolean	containsKey(char key) Tests if the specified object is a key in this hashtable.
boolean	containsValue(java.lang.Object value) Returns true if this HashMap maps one or more keys to this value.
java.lang.Object	get(char key) Returns the value to which the specified key is mapped in this map.
boolean	isEmpty() Tests if this hashtable maps no keys to values.
java.lang.Object	put(char key, java.lang.Object value) Maps the specified key to the specified value in this hashtable.
protected void	rehash() Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently.
java.lang.Object	remove(char key) Removes the key (and its corresponding value) from this hashtable.
int	size() Returns the number of keys in this hashtable.

Methods inherited from class java.lang.Object

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

Constructor Detail

CharHashMap

public CharHashMap()

Constructs a new, empty hashtable with a default capacity and load factor, which is 20 and 0.75 respectively.

CharHashMap

public CharHashMap(int initialCapacity)

Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.

Parameters:

initialCapacity - the initial capacity of the hashtable.

Throws:

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

CharHashMap

public CharHashMap(int initialCapacity,
                   float loadFactor)

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

Parameters:

initialCapacity - the initial capacity of the hashtable.

loadFactor - the load factor of the hashtable.

Throws:

java.lang.IllegalArgumentException - if the initial capacity is less than zero, or if the load factor is nonpositive.

Method Detail

size

public int size()

Returns the number of keys in this hashtable.

Returns:

the number of keys in this hashtable.

isEmpty

public boolean isEmpty()

Tests if this hashtable maps no keys to values.

Returns:

true if this hashtable maps no keys to values; false otherwise.

contains

public boolean contains(java.lang.Object value)

Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.

Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the collections framework).

Parameters:

value - a value to search for.

Returns:

true if and only if some key maps to the value argument in this hashtable as determined by the equals method; false otherwise.

Throws:

java.lang.NullPointerException - if the value is null.

See Also:

containsKey(char), containsValue(Object), Map

containsValue

public boolean containsValue(java.lang.Object value)

Returns true if this HashMap maps one or more keys to this value.

Note that this method is identical in functionality to contains (which predates the Map interface).

Parameters:

value - value whose presence in this HashMap is to be tested.

Since:

JDK1.2

See Also:

Map

containsKey

public boolean containsKey(char key)

Tests if the specified object is a key in this hashtable.

Parameters:

key - possible key.

Returns:

true if and only if the specified object is a key in this hashtable, as determined by the equals method; false otherwise.

See Also:

contains(Object)

get

public java.lang.Object get(char key)

Returns the value to which the specified key is mapped in this map.

Parameters:

key - a key in the hashtable.

Returns:

the value to which the key is mapped in this hashtable; null if the key is not mapped to any value in this hashtable.

See Also:

put(char, Object)

rehash

protected void rehash()

Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.

put

public java.lang.Object put(char key,
                            java.lang.Object value)

Maps the specified key to the specified value in this hashtable. The key cannot be null.

The value can be retrieved by calling the get method with a key that is equal to the original key.

Parameters:

key - the hashtable key.

value - the value.

Returns:

the previous value of the specified key in this hashtable, or null if it did not have one.

Throws:

java.lang.NullPointerException - if the key is null.

See Also:

get(char)

remove

public java.lang.Object remove(char key)

Removes the key (and its corresponding value) from this hashtable. This method does nothing if the key is not in the hashtable.

Parameters:

key - the key that needs to be removed.

Returns:

the value to which the key had been mapped in this hashtable, or null if the key did not have a mapping.

clear

public void clear()

Clears this hashtable so that it contains no keys.