edu.northwestern.at.utils.cache

Class SoftReferenceCache<K,V>

java.lang.Object

edu.northwestern.at.utils.cache.SoftReferenceCache<K,V>

All Implemented Interfaces:

Cache<K,V>

public class SoftReferenceCache<K,V>
extends java.lang.Object
implements Cache<K,V>

A cache that uses soft references. Values in this cache are expired by the VM in response to memory needs. For more information on how this works, see the JavaDoc for the java.lang.ref package.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.Map<K,java.lang.ref.SoftReference<V>>	cacheMap Map holding cached values.

Constructor Summary

Constructors

Constructor and Description
SoftReferenceCache() Create cache.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clear all entries in the cache.
boolean	containsKey(K key) True if cache contains a specified key.
V	get(K key) Retrieve a cached value.
V	put(K key, V value) Add or replace a cached value.
V	remove(K key) Remove a specific entry from the cache.
int	size() Return current size of cache.

Methods inherited from class java.lang.Object

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

Field Detail

cacheMap

protected java.util.Map<K,java.lang.ref.SoftReference<V>> cacheMap

Map holding cached values.

Constructor Detail

SoftReferenceCache

public SoftReferenceCache()

Create cache.

Method Detail

clear

public void clear()

Clear all entries in the cache.

Specified by:

clear in interface Cache<K,V>

containsKey

public boolean containsKey(K key)

True if cache contains a specified key.

Specified by:

containsKey in interface Cache<K,V>

Parameters:

key - The key to look up.

Returns:

true if the cache contains the key.

get

public V get(K key)

Retrieve a cached value.

Specified by:

get in interface Cache<K,V>

Parameters:

key - The key of the entry to retrieve.

Returns:

The value of the cached entry specified by key; null if the cache does not contain the key.

put

public V put(K key,
    V value)

Add or replace a cached value.

Specified by:

put in interface Cache<K,V>

Parameters:

key - The key of the entry to add.

value - The value of the entry to add.

Returns:

The value of any existing cached entry specified by the key; null if the cache does not contain the key.

remove

public V remove(K key)

Remove a specific entry from the cache.

Specified by:

remove in interface Cache<K,V>

Parameters:

key - The key of the entry to remove.

Returns:

The entry removed, or null if none.

size

public int size()

Return current size of cache.

Specified by:

size in interface Cache<K,V>

Returns:

Number of entries (keys) currently stored in cache.