Package jade.util

Class HashCache

java.lang.Object

jade.util.HashCache

All Implemented Interfaces:

Map

public class HashCache
extends Object
implements Map

This class is a cache with fixed dimension that can be set in the constructur. All element are indexed with an hashcode. When an element is added and the cache is already full,the oldest element is deleted.

Version:

$Date$ $Revision$

Author:

Alessandro Chiarotto, Fabio Bellifemine - TILAB S.p.A.

Constructor Summary

Constructors

Constructor	Description
HashCache(int cacheSize)	Constructs a new, empty HashCache with the specified size.

Method Summary

Modifier and Type	Method	Description
Object	add(Object o)	Adds the specified element to this hashcache if it is not already present.
void	clear()	Clears the cache, removing all key-value pairs
boolean	contains(Object o)	Tests if the specified object is a key in this hashcache.
boolean	containsKey(Object key)	Returns true if this map contains a mapping for the specified key.
Object	get(Object key)	Retrieves a cached element.
boolean	isEmpty()	Returns true if this map contains no key-value mappings.
Set	keySet()	Returns a set view of the keys contained in this map.
Object	put(Object key, Object value)	Adds a key-value pair to this cache
Object	remove(Object key)	Remove an existing key-value pair from the cache
int	size()	Returns the number of mappings in this map.
Collection	values()	Returns a Collection view of the values contained in this map.

Methods inherited from class java.lang.Object

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

Constructor Detail

HashCache

public HashCache(int cacheSize)

Constructs a new, empty HashCache with the specified size.

Parameters:

cacheSize - is the size of this cache

Method Detail

add

public Object add(Object o)

Adds the specified element to this hashcache if it is not already present. If the cache is already full,the oldest element is deleted.

Parameters:

o - element to be added to this set.

Returns:

o the specified added object element.

put

public Object put(Object key,
                  Object value)

Adds a key-value pair to this cache

Specified by:

put in interface Map

Parameters:

key - The key with which the value can be retrieved in the future.

value - The value to store in the cache.

Returns:

The value previously associated to the key, if any.

See Also:

Map

remove

public Object remove(Object key)

Remove an existing key-value pair from the cache

Specified by:

remove in interface Map

Parameters:

o - The key to be removed (together with its associated value.

Returns:

The value associated to the given key, if any.

See Also:

Map

contains

public boolean contains(Object o)

Tests if the specified object is a key in this hashcache. present. the oldest element is deleted.

Parameters:

o - element to be added to this set.

Returns:

true if the haschcache contains the object o, otherwise false

get

public Object get(Object key)

Retrieves a cached element. The retrieved element is also marked as the last used one, so that the cache replacement policy becomes LRU instead of FIFO.

Specified by:

get in interface Map

Parameters:

o - The

Returns:

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

See Also:

Map

clear

public void clear()

Clears the cache, removing all key-value pairs

Specified by:

clear in interface Map

See Also:

Map

isEmpty

public boolean isEmpty()

Description copied from interface: Map

Returns true if this map contains no key-value mappings.

Specified by:

isEmpty in interface Map

Returns:

true if this map contains no key-value mappings.

See Also:

Map

keySet

public Set keySet()

Description copied from interface: Map

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

Specified by:

keySet in interface Map

Returns:

a set view of the keys contained in this map.

See Also:

Map

values

public Collection values()

Description copied from interface: Map

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

Specified by:

values in interface Map

Returns:

the Collection of elements contained in this map.

See Also:

Map

containsKey

public boolean containsKey(Object key)

Description copied from interface: Map

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

Specified by:

containsKey in interface Map

Parameters:

key - key whose presence in this map is to be tested.

Returns:

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

See Also:

Map

size

public int size()

Description copied from interface: Map

Returns the number of mappings in this map.

Specified by:

size in interface Map

See Also:

Map