org.apache.tomcat.util.collections

Class SimpleHashtable

java.lang.Object

org.apache.tomcat.util.collections.SimpleHashtable

All Implemented Interfaces:

Enumeration

public final class SimpleHashtable
extends Object
implements 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.

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()
Object	get(String key) Returns the value to which the specified key is mapped in this hashtable ...
Object	getInterned(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.
Enumeration	keys() Returns an enumeration of the keys in this hashtable.
Object	nextElement() Used to view this as an enumeration; returns the next key in the enumeration.
Object	put(Object key, Object value) Maps the specified key to the specified value in this hashtable.
Object	remove(Object key)
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

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 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 Enumeration

nextElement

public Object nextElement()

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

Specified by:

nextElement in interface Enumeration

getInterned

public Object getInterned(String key)

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

get

public Object get(String key)

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

put

public Object put(Object key,
                  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.

remove

public Object remove(Object key)