com.xmlmind.util

Class LinearHashtable<K,V>

java.lang.Object

com.xmlmind.util.LinearHashtable<K,V>

All Implemented Interfaces:

Serializable, Cloneable

Direct Known Subclasses:

IdentityLinearHashtable

public class LinearHashtable<K,V>
extends Object
implements Cloneable, Serializable

A hashtable which is more compact and less efficient than Hashtable.

This implementation is the one used by Smalltalk. It is useful if you need to have hundreds or even thousands of very small hashtables (with up to 3 entries for most instances).

LinearHashtable has exactly the same API as java.util.Hashtable, therefore there is no need to document again this API here.

Note that the iterators returned by the methods of this class do not support the remove operation and do not detect concurrent modification.

This class is not thread-safe.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
LinearHashtable() Constructs a hashtable with an initial capacity of 3 key/value pairs.
LinearHashtable(int capacity) Constructs a hashtable with the specified initial capacity.

Method Summary

Modifier and Type	Method and Description
void	clear()
Object	clone()
boolean	contains(V value)
boolean	containsKey(K key)
void	copyElementsInto(V[] array) Copies the elements contained in this hashtable to the specified array.
void	copyKeysInto(K[] array) Copies the keys contained in this hashtable to the specified array.
Iterator<V>	elements()
Iterator<KeyValuePair<K,V>>	entries() Returns an Iterator over all the entries contained in this hashtable.
V	get(K key)
Object[]	getKeyValueTable() Returns the Object table used to implement this kind of hashtables.
boolean	isEmpty()
Iterator<K>	keys()
V	put(K key, V value)
V	remove(K key)
int	size() Returns the number of key/value pairs currently stored in this hashtable.
String	toString() Returns a string representation of this hashtable which may be used during debugging.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

LinearHashtable

public LinearHashtable()

Constructs a hashtable with an initial capacity of 3 key/value pairs.

LinearHashtable

public LinearHashtable(int capacity)

Constructs a hashtable with the specified initial capacity.

Parameters:

capacity - the initial capacity expressed in number of key/value pairs

Method Detail

size

public int size()

Returns the number of key/value pairs currently stored in this hashtable. Note that calling this method is more expensive than calling Hashtable.size() because the size is recomputed each time this method is called.

Returns:

the number of key/value pairs currently stored in this hashtable

isEmpty

public boolean isEmpty()

contains

public boolean contains(V value)

containsKey

public boolean containsKey(K key)

get

public V get(K key)

put

public V put(K key,
             V value)

remove

public V remove(K key)

clear

public void clear()

clone

public Object clone()

Overrides:

clone in class Object

toString

public String toString()

Returns a string representation of this hashtable which may be used during debugging.

Overrides:

toString in class Object

copyKeysInto

public void copyKeysInto(K[] array)

Copies the keys contained in this hashtable to the specified array.

Parameters:

array - the array where the keys are to be copied

copyElementsInto

public void copyElementsInto(V[] array)

Copies the elements contained in this hashtable to the specified array.

Parameters:

array - the array where the elements are to be copied

keys

public Iterator<K> keys()

elements

public Iterator<V> elements()

entries

public Iterator<KeyValuePair<K,V>> entries()

Returns an Iterator over all the entries contained in this hashtable.

For efficiency reasons, the entry returned by this Iterator is always the same object. Copy it if you need to store this entry.

getKeyValueTable

public Object[] getKeyValueTable()

Returns the Object table used to implement this kind of hashtables.

Keys are found at even indices.

If the key object is not null, it is immediately followed by its associated value (which are therefore found at even indices).

For example, the following code can be used to dump a LinearHashtable:

Object[] table = htab.getKeyValueTable();
 for (int i = 0; i < table.length; i += 2) {
     if (table[i] != null) {
         System.err.println("key=" + table[i]);
         System.err.println("value=" + table[i+1]);
     }
  }

Only use this method when you have a desperate need for speed. Otherwise, please use entries().

And, of course, do not modify the contents of the table returned by this method.