com.sun.xml.dtdparser

Class SimpleHashtable

java.lang.Object

com.sun.xml.dtdparser.SimpleHashtable

All Implemented Interfaces:

java.util.Enumeration

final class SimpleHashtable
extends java.lang.Object
implements java.util.Enumeration

This class implements a special purpose hashtable. It works like a normal java.util.Hashtable except that:

1. Keys to "get" are strings which are known to be interned, so that "==" is used instead of "String.equals". (Interning could be document-relative instead of global.)

2. It's not synchronized, since it's to be used only by one thread at a time.

3. The keys () enumerator allocates no memory, with live updates to the data disallowed.

4. It's got fewer bells and whistles: fixed threshold and load factor, no JDK 1.2 collection support, only keys can be enumerated, things can't be removed, simpler inheritance; more.

The overall result is that it's less expensive to use these in performance-critical locations, in terms both of CPU and memory, than java.util.Hashtable instances. In this package it makes a significant difference when normalizing attributes, which is done for each start-element construct.

Version:

$Revision: 1.2 $

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	SimpleHashtable.Entry Hashtable collision list.

Field Summary

Fields

Modifier and Type	Field and Description
private int	count
private SimpleHashtable.Entry	current
private int	currentBucket
private static float	loadFactor
private SimpleHashtable.Entry[]	table
private int	threshold

Constructor Summary

Constructors

Constructor and Description
SimpleHashtable() Constructs a new, empty hashtable with a default capacity.
SimpleHashtable(int initialCapacity) Constructs a new, empty hashtable with the specified initial capacity.

Method Summary

Modifier and Type	Method and Description
void	clear()
java.lang.Object	get(java.lang.String key) Returns the value to which the specified key is mapped in this hashtable.
java.lang.Object	getNonInterned(java.lang.String key) Returns the value to which the specified key is mapped in this hashtable ...
boolean	hasMoreElements() Used to view this as an enumeration; returns true if there are more keys to be enumerated.
java.util.Enumeration	keys() Returns an enumeration of the keys in this hashtable.
java.lang.Object	nextElement() Used to view this as an enumeration; returns the next key in the enumeration.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Maps the specified key to the specified value in this hashtable.
private void	rehash() Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently.
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

Field Detail

table

private SimpleHashtable.Entry[] table

current

private SimpleHashtable.Entry current

currentBucket

private int currentBucket

count

private int count

threshold

private int threshold

loadFactor

private static final float loadFactor

See Also:

Constant Field Values

Constructor Detail

SimpleHashtable

public SimpleHashtable(int initialCapacity)

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

Parameters:

initialCapacity - the initial capacity of the hashtable.

SimpleHashtable

public SimpleHashtable()

Constructs a new, empty hashtable with a default capacity.

Method Detail

clear

public void clear()

size

public int size()

Returns the number of keys in this hashtable.

Returns:

the number of keys in this hashtable.

keys

public java.util.Enumeration keys()

Returns an enumeration of the keys in this hashtable.

Returns:

an enumeration of the keys in this hashtable.

See Also:

Enumeration

hasMoreElements

public boolean hasMoreElements()

Used to view this as an enumeration; returns true if there are more keys to be enumerated.

Specified by:

hasMoreElements in interface java.util.Enumeration

nextElement

public java.lang.Object nextElement()

Used to view this as an enumeration; returns the next key in the enumeration.

Specified by:

nextElement in interface java.util.Enumeration

get

public java.lang.Object get(java.lang.String key)

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

getNonInterned

public java.lang.Object getNonInterned(java.lang.String key)

Returns the value to which the specified key is mapped in this hashtable ... the key isn't necessarily interned, though.

rehash

private 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(java.lang.Object key,
                            java.lang.Object value)

Maps the specified key to the specified value in this hashtable. Neither the key nor the value can be null.

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