com.atlassian.jira.util.collect
Class LRUMap<K,V>

java.lang.Object
  java.util.AbstractMap<K,V>
      java.util.HashMap<K,V>
          java.util.LinkedHashMap<K,V>
              com.atlassian.jira.util.collect.LRUMap<K,V>

Type Parameters:

K - key type

V - value type

All Implemented Interfaces:

Serializable, Cloneable, Map<K,V>

@NotThreadSafe
public class LRUMap<K,V>
extends LinkedHashMap<K,V>
implements Map<K,V>

A subclass of LinkedHashMap that is access ordered AND constrained in size.

It is very important that any multi-threaded access to this class be externally synchronised as even non mutative operations such as LinkedHashMap.get(Object) will cause internal modifications to the map order.

See Also:

LinkedHashMap, Serialized Form

Nested Class Summary

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

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

Nested classes/interfaces inherited from interface java.util.Map

Map.Entry<K,V>

Method Summary

static <K,V> Map<K,V>	newLRUMap(int capacity) Get a map that is access ordered and has the specified capacity.
protected boolean	removeEldestEntry(Map.Entry<K,V> eldest)
static <K,V> Map<K,V>	synchronizedLRUMap(int capacity) Get a map that is access ordered and has the specified capacity that is thread-safe.

Methods inherited from class java.util.LinkedHashMap

clear, containsValue, get

Methods inherited from class java.util.HashMap

clone, containsKey, entrySet, isEmpty, keySet, put, putAll, remove, size, values

Methods inherited from class java.util.AbstractMap

equals, hashCode, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Method Detail

newLRUMap

public static <K,V> Map<K,V> newLRUMap(int capacity)

Get a map that is access ordered and has the specified capacity.

Type Parameters:

K - the key type

V - the value type

Parameters:

capacity - the maximum capacity

Returns:

an instance of LRUMap

synchronizedLRUMap

public static <K,V> Map<K,V> synchronizedLRUMap(int capacity)

Get a map that is access ordered and has the specified capacity that is thread-safe.

Type Parameters:

K - the key type

V - the value type

Parameters:

capacity - the maximum capacity

Returns:

an instance of LRUMap wrapped in a synchronized map.

removeEldestEntry

protected final boolean removeEldestEntry(Map.Entry<K,V> eldest)

Overrides:

removeEldestEntry in class LinkedHashMap<K,V>