K - the type of keys maintained by this mapV - the type of mapped valuespublic class ConcurrentLinkedHashMap<K,V> extends AbstractMap<K,V> implements ConcurrentMap<K,V>, Serializable
ConcurrentHashMap in that it maintains a page replacement algorithm that
 is used to evict an entry when the map has exceeded its capacity. Unlike the
 Java Collections Framework, this map does not have a publicly visible
 constructor and instances are created through a ConcurrentLinkedHashMap.Builder.
 
 An entry is evicted from the map when the weighted capacity exceeds its
 maximum weighted capacity threshold. A Weigher instance determines how
 many units of capacity that a value consumes. The default weigher assigns each value a
 weight of 1 to bound the map by the total number of key-value pairs. A map
 that holds collections may choose to weigh values by the number of elements in the
 collection and bound the map by the total number of elements that it contains. A change
 to a value that modifies its weight requires that an update operation is performed on
 the map.
 
 An EvictionListener may be supplied for notification when an entry is evicted
 from the map. This listener is invoked on a caller's thread and will not block other
 threads from operating on the map. An implementation should be aware that the caller's
 thread will not expect long execution times or failures as a side effect of the
 listener being notified. Execution safety and a fast turn around time can be achieved
 by performing the operation asynchronously, such as by submitting a task to an
 ExecutorService.
 
The concurrency level determines the number of threads that can concurrently modify the table. Using a significantly higher or lower value than needed can waste space or lead to thread contention, but an estimate within an order of magnitude of the ideal value does not usually have a noticeable impact. Because placement in hash tables is essentially random, the actual concurrency will vary.
 This class and its views and iterators implement all of the optional methods
 of the Map and Iterator interfaces.
 
 Like Hashtable but unlike HashMap, this class does
 not allow null to be used as a key or value. Unlike
 LinkedHashMap, this class does not provide predictable
 iteration order. A snapshot of the keys and entries may be obtained in ascending and
 descending order of retention.
| Modifier and Type | Class and Description | 
|---|---|
| static class  | ConcurrentLinkedHashMap.Builder<K,V>A builder that creates  ConcurrentLinkedHashMapinstances. | 
AbstractMap.SimpleImmutableEntry<K,V>| Modifier and Type | Method and Description | 
|---|---|
| Set<K> | ascendingKeySet()Returns a unmodifiable snapshot  Setview of the keys contained in this map. | 
| Set<K> | ascendingKeySetWithLimit(int limit)Returns an unmodifiable snapshot  Setview of the keys contained in this
 map. | 
| Map<K,V> | ascendingMap()Returns an unmodifiable snapshot  Mapview of the mappings contained in this
 map. | 
| Map<K,V> | ascendingMapWithLimit(int limit)Returns an unmodifiable snapshot  Mapview of the mappings contained in this
 map. | 
| int | capacity()Retrieves the maximum weighted capacity of the map. | 
| void | clear() | 
| boolean | containsKey(Object key) | 
| boolean | containsValue(Object value) | 
| Set<K> | descendingKeySet()Returns an unmodifiable snapshot  Setview of the keys contained in this
 map. | 
| Set<K> | descendingKeySetWithLimit(int limit)Returns an unmodifiable snapshot  Setview of the keys contained in this
 map. | 
| Map<K,V> | descendingMap()Returns an unmodifiable snapshot  Mapview of the mappings contained in this
 map. | 
| Map<K,V> | descendingMapWithLimit(int limit)Returns an unmodifiable snapshot  Mapview of the mappings contained in this
 map. | 
| Set<Map.Entry<K,V>> | entrySet() | 
| V | get(Object key) | 
| boolean | isEmpty() | 
| Set<K> | keySet() | 
| V | put(K key,
   V value) | 
| V | putIfAbsent(K key,
           V value) | 
| V | remove(Object key) | 
| boolean | remove(Object key,
      Object value) | 
| V | replace(K key,
       V value) | 
| boolean | replace(K key,
       V oldValue,
       V newValue) | 
| void | setCapacity(int capacity)Sets the maximum weighted capacity of the map and eagerly evicts entries until it
 shrinks to the appropriate size. | 
| int | size() | 
| Collection<V> | values() | 
| int | weightedSize()Returns the weighted size of this map. | 
finalize, getClass, notify, notifyAll, wait, wait, waitcompute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, replaceAllpublic int capacity()
public void setCapacity(int capacity)
capacity - the maximum weighted capacity of the mapIllegalArgumentException - if the capacity is negativepublic boolean isEmpty()
public int size()
public int weightedSize()
public void clear()
public boolean containsKey(Object key)
containsKey in interface Map<K,V>containsKey in class AbstractMap<K,V>public boolean containsValue(Object value)
containsValue in interface Map<K,V>containsValue in class AbstractMap<K,V>public V putIfAbsent(K key, V value)
putIfAbsent in interface ConcurrentMap<K,V>putIfAbsent in interface Map<K,V>public Set<K> ascendingKeySet()
Set view of the keys contained in this map.
 The set's iterator returns the keys whose order of iteration is the ascending order
 in which its entries are considered eligible for retention, from the least-likely
 to be retained to the most-likely.
 
 Beware that, unlike in keySet(), obtaining the set is NOT a
 constant-time operation. Because of the asynchronous nature of the page replacement
 policy, determining the retention ordering requires a traversal of the keys.
public Set<K> ascendingKeySetWithLimit(int limit)
Set view of the keys contained in this
 map. The set's iterator returns the keys whose order of iteration is the ascending
 order in which its entries are considered eligible for retention, from the
 least-likely to be retained to the most-likely.
 
 Beware that, unlike in keySet(), obtaining the set is NOT a
 constant-time operation. Because of the asynchronous nature of the page replacement
 policy, determining the retention ordering requires a traversal of the keys.
limit - the maximum size of the returned setIllegalArgumentException - if the limit is negativepublic Set<K> descendingKeySet()
Set view of the keys contained in this
 map. The set's iterator returns the keys whose order of iteration is the descending
 order in which its entries are considered eligible for retention, from the
 most-likely to be retained to the least-likely.
 
 Beware that, unlike in keySet(), obtaining the set is NOT a
 constant-time operation. Because of the asynchronous nature of the page replacement
 policy, determining the retention ordering requires a traversal of the keys.
public Set<K> descendingKeySetWithLimit(int limit)
Set view of the keys contained in this
 map. The set's iterator returns the keys whose order of iteration is the descending
 order in which its entries are considered eligible for retention, from the
 most-likely to be retained to the least-likely.
 
 Beware that, unlike in keySet(), obtaining the set is NOT a
 constant-time operation. Because of the asynchronous nature of the page replacement
 policy, determining the retention ordering requires a traversal of the keys.
limit - the maximum size of the returned setIllegalArgumentException - if the limit is negativepublic Collection<V> values()
public Map<K,V> ascendingMap()
Map view of the mappings contained in this
 map. The map's collections return the mappings whose order of iteration is the
 ascending order in which its entries are considered eligible for retention, from
 the least-likely to be retained to the most-likely.
 Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.
public Map<K,V> ascendingMapWithLimit(int limit)
Map view of the mappings contained in this
 map. The map's collections return the mappings whose order of iteration is the
 ascending order in which its entries are considered eligible for retention, from
 the least-likely to be retained to the most-likely.
 Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.
limit - the maximum size of the returned mapIllegalArgumentException - if the limit is negativepublic Map<K,V> descendingMap()
Map view of the mappings contained in this
 map. The map's collections return the mappings whose order of iteration is the
 descending order in which its entries are considered eligible for retention, from
 the most-likely to be retained to the least-likely.
 Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.
public Map<K,V> descendingMapWithLimit(int limit)
Map view of the mappings contained in this
 map. The map's collections return the mappings whose order of iteration is the
 descending order in which its entries are considered eligible for retention, from
 the most-likely to be retained to the least-likely.
 Beware that obtaining the mappings is NOT a constant-time operation. Because of the asynchronous nature of the page replacement policy, determining the retention ordering requires a traversal of the entries.
limit - the maximum size of the returned mapIllegalArgumentException - if the limit is negativeCopyright © 2001–2023 Apache Cayenne. All rights reserved.