org.swblocks.jbl.cache

Class LruCache<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,V>

java.util.LinkedHashMap<K,V>

org.swblocks.jbl.cache.LruCache<K,V>

Type Parameters:

K - type of key stored in the Map.

V - type of values stored in the Map.

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.util.Map<K,V>

public final class LruCache<K,V>
extends java.util.LinkedHashMap<K,V>

Class providing a simple LRU cache implementation using LinkedHashMap.

The implementation is not thread safe and access must be synchronised in a multi threaded application. For example:

     final int initialCapacity = 10;
     final int maximumEntries = 20;

     final Map<DateRange, Object> cache =
          Collections.synchronizedMap(new LruCache(initialCapacity, maximumCapacity, 0.75F));
 

The LinkedHashMap orders its entries by access order so that once the size of the map reaches the maximumEntries value, the least read entry is removed from the map when a new entry is added.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object object)
static <K,V> LruCache<K,V>	getCache(int initialCapacity, int maximumEntries, float loadFactor) Static method to create and return an new instance of a simple LRU cache.
int	hashCode()
protected boolean	removeEldestEntry(java.util.Map.Entry eldest)

Methods inherited from class java.util.LinkedHashMap

clear, containsValue, entrySet, forEach, get, getOrDefault, keySet, replaceAll, values

Methods inherited from class java.util.HashMap

clone, compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Methods inherited from class java.util.AbstractMap

toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map

compute, computeIfAbsent, computeIfPresent, containsKey, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, size

Method Detail

getCache

public static <K,V> LruCache<K,V> getCache(int initialCapacity,
                                           int maximumEntries,
                                           float loadFactor)

Static method to create and return an new instance of a simple LRU cache.

Type Parameters:

K - the key object type

V - the value object type

Parameters:

initialCapacity - the initial capacity of the cache

maximumEntries - the maximum number of entries allowed in this cache

loadFactor - the map load factor

Returns:

the new instance of the LruCache

removeEldestEntry

protected boolean removeEldestEntry(java.util.Map.Entry eldest)

Overrides:

removeEldestEntry in class java.util.LinkedHashMap<K,V>

equals

public boolean equals(java.lang.Object object)

Specified by:

equals in interface java.util.Map<K,V>

Overrides:

equals in class java.util.AbstractMap<K,V>

hashCode

public int hashCode()

Specified by:

hashCode in interface java.util.Map<K,V>

Overrides:

hashCode in class java.util.AbstractMap<K,V>