类 ConcurrentReferenceHashMap<K,​V>

构造器详细资料

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap()

  Create a new ConcurrentReferenceHashMap instance.

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity,
                                    float loadFactor)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

  loadFactor - the load factor. When the average number of references per table exceeds this value resize will be attempted

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity,
                                    int concurrencyLevel)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

  concurrencyLevel - the expected number of threads that will concurrently write to the map

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity,
                                    ConcurrentReferenceHashMap.ReferenceType referenceType)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

  referenceType - the reference type used for entries (soft or weak)

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity,
                                    float loadFactor,
                                    int concurrencyLevel)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

  loadFactor - the load factor. When the average number of references per table exceeds this value, resize will be attempted.

  concurrencyLevel - the expected number of threads that will concurrently write to the map

• ConcurrentReferenceHashMap

  public ConcurrentReferenceHashMap​(int initialCapacity,
                                    float loadFactor,
                                    int concurrencyLevel,
                                    ConcurrentReferenceHashMap.ReferenceType referenceType)

  Create a new ConcurrentReferenceHashMap instance.

  参数:

  initialCapacity - the initial capacity of the map

  loadFactor - the load factor. When the average number of references per table exceeds this value, resize will be attempted.

  concurrencyLevel - the expected number of threads that will concurrently write to the map

  referenceType - the reference type used for entries (soft or weak)

方法详细资料

• getLoadFactor

  protected final float getLoadFactor()

• getSegmentsSize

  protected final int getSegmentsSize()

• getSegment

  protected final ConcurrentReferenceHashMap.Segment getSegment​(int index)

• createReferenceManager

  protected ConcurrentReferenceHashMap.ReferenceManager createReferenceManager()

  Factory method that returns the ConcurrentReferenceHashMap.ReferenceManager. This method will be called once for each ConcurrentReferenceHashMap.Segment.

  返回:

  a new reference manager

• getHash

  protected int getHash​(Object o)

  Get the hash for a given object, apply an additional hash function to reduce collisions. This implementation uses the same Wang/Jenkins algorithm as ConcurrentHashMap. Subclasses can override to provide alternative hashing.

  参数:

  o - the object to hash (may be null)

  返回:

  the resulting hash code

• get

  public V get​(Object key)

  指定者:

  get 在接口中 Map<K,​V>

  覆盖:

  get 在类中 AbstractMap<K,​V>

• getOrDefault

  public V getOrDefault​(Object key,
                        V defaultValue)

  指定者:

  getOrDefault 在接口中 ConcurrentMap<K,​V>

  指定者:

  getOrDefault 在接口中 Map<K,​V>

• containsKey

  public boolean containsKey​(Object key)

  指定者:

  containsKey 在接口中 Map<K,​V>

  覆盖:

  containsKey 在类中 AbstractMap<K,​V>

• getReference

  protected final ConcurrentReferenceHashMap.Reference<K,​V> getReference​(Object key,
                                                                               ConcurrentReferenceHashMap.Restructure restructure)

  Return a ConcurrentReferenceHashMap.Reference to the ConcurrentReferenceHashMap.Entry for the specified key, or null if not found.

  参数:

  key - the key (can be null)

  restructure - types of restructure allowed during this call

  返回:

  the reference, or null if not found

• put

  public V put​(K key,
               V value)

  指定者:

  put 在接口中 Map<K,​V>

  覆盖:

  put 在类中 AbstractMap<K,​V>

• putIfAbsent

  public V putIfAbsent​(K key,
                       V value)

  指定者:

  putIfAbsent 在接口中 ConcurrentMap<K,​V>

  指定者:

  putIfAbsent 在接口中 Map<K,​V>

• remove

  public V remove​(Object key)

  指定者:

  remove 在接口中 Map<K,​V>

  覆盖:

  remove 在类中 AbstractMap<K,​V>

• remove

  public boolean remove​(Object key,
                        Object value)

  指定者:

  remove 在接口中 ConcurrentMap<K,​V>

  指定者:

  remove 在接口中 Map<K,​V>

• replace

  public boolean replace​(K key,
                         V oldValue,
                         V newValue)

  指定者:

  replace 在接口中 ConcurrentMap<K,​V>

  指定者:

  replace 在接口中 Map<K,​V>

• replace

  public V replace​(K key,
                   V value)

  指定者:

  replace 在接口中 ConcurrentMap<K,​V>

  指定者:

  replace 在接口中 Map<K,​V>

• clear

  public void clear()

  指定者:

  clear 在接口中 Map<K,​V>

  覆盖:

  clear 在类中 AbstractMap<K,​V>

• purgeUnreferencedEntries

  public void purgeUnreferencedEntries()

  Remove any entries that have been garbage collected and are no longer referenced. Under normal circumstances garbage collected entries are automatically purged as items are added or removed from the Map. This method can be used to force a purge, and is useful when the Map is read frequently but updated less often.

• size

  public int size()

  指定者:

  size 在接口中 Map<K,​V>

  覆盖:

  size 在类中 AbstractMap<K,​V>

• isEmpty

  public boolean isEmpty()

  指定者:

  isEmpty 在接口中 Map<K,​V>

  覆盖:

  isEmpty 在类中 AbstractMap<K,​V>

• entrySet

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

  指定者:

  entrySet 在接口中 Map<K,​V>

  指定者:

  entrySet 在类中 AbstractMap<K,​V>

• calculateShift

  protected static int calculateShift​(int minimumValue,
                                      int maximumValue)

  Calculate a shift value that can be used to create a power-of-two value between the specified maximum and minimum values.

  参数:

  minimumValue - the minimum value

  maximumValue - the maximum value

  返回:

  the calculated shift (use 1 << shift to obtain a value)