Package org.jxmpp.util.cache

Class LruCache<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

java.util.HashMap<K,V>

java.util.LinkedHashMap<K,V>

org.jxmpp.util.cache.LruCache<K,V>

Type Parameters:

K - the type of the keys of this cache.

V - the type of the values this cache caches.

All Implemented Interfaces:

Serializable, Cloneable, Map<K,V>, Cache<K,V>

public class LruCache<K,V>
extends LinkedHashMap<K,V>
implements Cache<K,V>

A specialized Map that is size-limited (using an LRU algorithm). The Map is thread-safe.

See Also:

• 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>

Constructor Summary

Constructors

Constructor	Description
LruCache(int maxSize)	Create a new cache and specify the maximum size of for the cache in bytes, and the maximum lifetime of objects.

Method Summary

Modifier and Type	Method	Description
final void	clear()
final boolean	containsKey(Object key)
final boolean	containsValue(Object value)
final Set<Map.Entry<K,V>>	entrySet()
final V	get(Object key)
final long	getCacheHits()	Get the number of cache hits.
final long	getCacheMisses()	Get the number of cache misses.
final int	getMaxCacheSize()	Return the maximum cache Size.
final boolean	isEmpty()
final Set<K>	keySet()
final V	lookup(K key)	Returns the value of the specified key, or null.
final V	put(K key, V value)	Put a value in the cache.
final void	putAll(Map<? extends K,? extends V> m)
final V	remove(Object key)
protected final boolean	removeEldestEntry(Map.Entry<K,V> eldest)
final void	setMaxCacheSize(int maxCacheSize)	Set the maximum cache size.
final int	size()
final Collection<V>	values()

Methods inherited from class java.util.LinkedHashMap

forEach, getOrDefault, replaceAll

Methods inherited from class java.util.HashMap

clone, compute, computeIfAbsent, computeIfPresent, merge, putIfAbsent, remove, replace, replace

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

compute, computeIfAbsent, computeIfPresent, equals, hashCode, merge, putIfAbsent, remove, replace, replace

Constructor Details

LruCache

public LruCache(int maxSize)

Create a new cache and specify the maximum size of for the cache in bytes, and the maximum lifetime of objects.

Parameters:

maxSize - the maximum number of objects the cache will hold. -1 means the cache has no max size.

Method Details

removeEldestEntry

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

Overrides:

removeEldestEntry in class LinkedHashMap<K,V>

put

public final V put(K key,
 V value)

Description copied from interface: Cache

Put a value in the cache.

Specified by:

put in interface Cache<K,V>

Specified by:

put in interface Map<K,V>

Overrides:

put in class HashMap<K,V>

Parameters:

key - the key of the value.

value - the value.

Returns:

the previous value or null.

lookup

public final V lookup(K key)

Description copied from interface: Cache

Returns the value of the specified key, or null.

Specified by:

lookup in interface Cache<K,V>

Parameters:

key - the key.

Returns:

the value found in the cache, or null.

get

public final V get(Object key)

Specified by:

get in interface Map<K,V>

Overrides:

get in class LinkedHashMap<K,V>

remove

public final V remove(Object key)

Specified by:

remove in interface Map<K,V>

Overrides:

remove in class HashMap<K,V>

clear

public final void clear()

Specified by:

clear in interface Map<K,V>

Overrides:

clear in class LinkedHashMap<K,V>

size

public final int size()

Specified by:

size in interface Map<K,V>

Overrides:

size in class HashMap<K,V>

isEmpty

public final boolean isEmpty()

Specified by:

isEmpty in interface Map<K,V>

Overrides:

isEmpty in class HashMap<K,V>

values

public final Collection<V> values()

Specified by:

values in interface Map<K,V>

Overrides:

values in class LinkedHashMap<K,V>

containsKey

public final boolean containsKey(Object key)

Specified by:

containsKey in interface Map<K,V>

Overrides:

containsKey in class HashMap<K,V>

putAll

public final void putAll(Map<? extends K,? extends V> m)

Specified by:

putAll in interface Map<K,V>

Overrides:

putAll in class HashMap<K,V>

containsValue

public final boolean containsValue(Object value)

Specified by:

containsValue in interface Map<K,V>

Overrides:

containsValue in class LinkedHashMap<K,V>

entrySet

public final Set<Map.Entry<K,V>> entrySet()

Specified by:

entrySet in interface Map<K,V>

Overrides:

entrySet in class LinkedHashMap<K,V>

keySet

public final Set<K> keySet()

Specified by:

keySet in interface Map<K,V>

Overrides:

keySet in class LinkedHashMap<K,V>

getCacheHits

public final long getCacheHits()

Get the number of cache hits.

Returns:

the number of cache hits.

getCacheMisses

public final long getCacheMisses()

Get the number of cache misses.

Returns:

the number of cache misses.

getMaxCacheSize

public final int getMaxCacheSize()

Description copied from interface: Cache

Return the maximum cache Size.

Specified by:

getMaxCacheSize in interface Cache<K,V>

Returns:

the maximum cache size.

setMaxCacheSize

public final void setMaxCacheSize(int maxCacheSize)

Description copied from interface: Cache

Set the maximum cache size.

Specified by:

setMaxCacheSize in interface Cache<K,V>

Parameters:

maxCacheSize - the new maximum cache size.