org.netbeans.core.network.utils

Class SimpleObjCache<K,V>

java.lang.Object

org.netbeans.core.network.utils.SimpleObjCache<K,V>

Type Parameters:

K - key

V - value

public class SimpleObjCache<K,V>
extends Object

Simple cache with a max capacity. Encapsulates Map.

Eviction is based on usage. Every time a value is retrieved from the cache its 'usage timestamp' will change. When the cache is full, the value with the oldest usage timestamp will be evicted.

This class is thread-safe and is very efficient for read operations (get). The write operation (put) will - if the cache is full - have performance which degrades linearly with the size of the cache as all elements will have to be inspected to find the eviction candidate. For this reason, the class is best suited for smaller caches (say less than 1000 elements).

Constructor Summary

Constructors

Constructor and Description
SimpleObjCache(int maxSize) Constructs a new cache with maxSize capacity.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all elements from the cache.
V	get(K key) Returns the value to which the specified key is mapped, or null if this cache contains no mapping for the key.
int	getCacheSize() Gets the current number of elements in the cache.
V	put(K key, V value) Puts a value into the cache mapped to the specified key.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleObjCache

public SimpleObjCache(int maxSize)

Constructs a new cache with maxSize capacity. When the cache is full, the value used/created the furthest in the past will be evicted to make room for a new element.

Parameters:

maxSize - capacity - any value larger than zero

Method Detail

put

public V put(K key,
             V value)

Puts a value into the cache mapped to the specified key.

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, or null if there was no mapping for the key

get

public V get(K key)

Returns the value to which the specified key is mapped, or null if this cache contains no mapping for the key.

Parameters:

key - the key whose associated value is to be returned

Returns:

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

getCacheSize

public int getCacheSize()

Gets the current number of elements in the cache.

Returns:

clear

public void clear()

Removes all elements from the cache. There is little reason to use this method as the cache will do its own house keeping.