com.alibaba.bytekit.utils.concurrent

类 ConcurrentWeakKeyHashMap<K,V>

java.lang.Object

java.util.AbstractMap<K,V>

com.alibaba.bytekit.utils.concurrent.ConcurrentWeakKeyHashMap<K,V>

类型参数:

K - the type of keys maintained by this map

V - the type of mapped values

所有已实现的接口:

ConcurrentMap<K,V>, Map<K,V>

public final class ConcurrentWeakKeyHashMap<K,V>
extends AbstractMap<K,V>
implements ConcurrentMap<K,V>

An alternative weak-key ConcurrentMap which is similar to ConcurrentHashMap.

嵌套类概要

从类继承的嵌套类/接口 java.util.AbstractMap

AbstractMap.SimpleImmutableEntry<K,V>

从接口继承的嵌套类/接口 java.util.Map

Map.Entry<K,V>

构造器概要

构造器

构造器和说明
ConcurrentWeakKeyHashMap() Creates a new, empty map with a default initial capacity (16), reference types (weak keys, strong values), default load factor (0.75) and concurrencyLevel (16).
ConcurrentWeakKeyHashMap(int initialCapacity) Creates a new, empty map with the specified initial capacity, and with default reference types (weak keys, strong values), load factor (0.75) and concurrencyLevel (16).
ConcurrentWeakKeyHashMap(int initialCapacity, float loadFactor) Creates a new, empty map with the specified initial capacity and load factor and with the default reference types (weak keys, strong values), and concurrencyLevel (16).
ConcurrentWeakKeyHashMap(int initialCapacity, float loadFactor, int concurrencyLevel) Creates a new, empty map with the specified initial capacity, load factor and concurrency level.
ConcurrentWeakKeyHashMap(Map<? extends K,? extends V> m) Creates a new map with the same mappings as the given map.

方法概要

限定符和类型	方法和说明
void	clear() Removes all of the mappings from this map.
boolean	contains(Object value) Legacy method testing if some key maps into the specified value in this table.
boolean	containsKey(Object key) Tests if the specified object is a key in this table.
boolean	containsValue(Object value) Returns true if this map maps one or more keys to the specified value.
Enumeration<V>	elements() Returns an enumeration of the values in this table.
Set<Map.Entry<K,V>>	entrySet() Returns a Set view of the mappings contained in this map.
V	get(Object key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
Enumeration<K>	keys() Returns an enumeration of the keys in this table.
Set<K>	keySet() Returns a Set view of the keys contained in this map.
void	purgeStaleEntries() Removes any stale entries whose keys have been finalized.
V	put(K key, V value) Maps the specified key to the specified value in this table.
void	putAll(Map<? extends K,? extends V> m) Copies all of the mappings from the specified map to this one.
V	putIfAbsent(K key, V value)
V	remove(Object key) Removes the key (and its corresponding value) from this map.
boolean	remove(Object key, Object value)
V	replace(K key, V value)
boolean	replace(K key, V oldValue, V newValue)
int	size() Returns the number of key-value mappings in this map.
Collection<V>	values() Returns a Collection view of the values contained in this map.

从类继承的方法 java.util.AbstractMap

clone, equals, hashCode, toString

从类继承的方法 java.lang.Object

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

从接口继承的方法 java.util.concurrent.ConcurrentMap

compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, replaceAll

从接口继承的方法 java.util.Map

equals, hashCode

构造器详细资料

ConcurrentWeakKeyHashMap

public ConcurrentWeakKeyHashMap(int initialCapacity,
                                float loadFactor,
                                int concurrencyLevel)

Creates a new, empty map with the specified initial capacity, load factor and concurrency level.

参数:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.

loadFactor - the load factor threshold, used to control resizing. Resizing may be performed when the average number of elements per bin exceeds this threshold.

concurrencyLevel - the estimated number of concurrently updating threads. The implementation performs internal sizing to try to accommodate this many threads.

抛出:

IllegalArgumentException - if the initial capacity is negative or the load factor or concurrencyLevel are nonpositive.

ConcurrentWeakKeyHashMap

public ConcurrentWeakKeyHashMap(int initialCapacity,
                                float loadFactor)

Creates a new, empty map with the specified initial capacity and load factor and with the default reference types (weak keys, strong values), and concurrencyLevel (16).

参数:

initialCapacity - The implementation performs internal sizing to accommodate this many elements.

loadFactor - the load factor threshold, used to control resizing. Resizing may be performed when the average number of elements per bin exceeds this threshold.

抛出:

IllegalArgumentException - if the initial capacity of elements is negative or the load factor is nonpositive

ConcurrentWeakKeyHashMap

public ConcurrentWeakKeyHashMap(int initialCapacity)

Creates a new, empty map with the specified initial capacity, and with default reference types (weak keys, strong values), load factor (0.75) and concurrencyLevel (16).

参数:

initialCapacity - the initial capacity. The implementation performs internal sizing to accommodate this many elements.

抛出:

IllegalArgumentException - if the initial capacity of elements is negative.

ConcurrentWeakKeyHashMap

public ConcurrentWeakKeyHashMap()

Creates a new, empty map with a default initial capacity (16), reference types (weak keys, strong values), default load factor (0.75) and concurrencyLevel (16).

ConcurrentWeakKeyHashMap

public ConcurrentWeakKeyHashMap(Map<? extends K,? extends V> m)

Creates a new map with the same mappings as the given map. The map is created with a capacity of 1.5 times the number of mappings in the given map or 16 (whichever is greater), and a default load factor (0.75) and concurrencyLevel (16).

参数:

m - the map

方法详细资料

isEmpty

public boolean isEmpty()

Returns true if this map contains no key-value mappings.

指定者:

isEmpty 在接口中 Map<K,V>

覆盖:

isEmpty 在类中 AbstractMap<K,V>

返回:

true if this map contains no key-value mappings

size

public int size()

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

指定者:

size 在接口中 Map<K,V>

覆盖:

size 在类中 AbstractMap<K,V>

返回:

the number of key-value mappings in this map

get

public V get(Object key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

More formally, if this map contains a mapping from a key k to a value v such that key.equals(k), then this method returns v; otherwise it returns null. (There can be at most one such mapping.)

指定者:

get 在接口中 Map<K,V>

覆盖:

get 在类中 AbstractMap<K,V>

抛出:

NullPointerException - if the specified key is null

containsKey

public boolean containsKey(Object key)

Tests if the specified object is a key in this table.

指定者:

containsKey 在接口中 Map<K,V>

覆盖:

containsKey 在类中 AbstractMap<K,V>

参数:

key - possible key

返回:

true if and only if the specified object is a key in this table, as determined by the equals method; false otherwise.

抛出:

NullPointerException - if the specified key is null

containsValue

public boolean containsValue(Object value)

Returns true if this map maps one or more keys to the specified value. Note: This method requires a full internal traversal of the hash table, and so is much slower than method containsKey.

指定者:

containsValue 在接口中 Map<K,V>

覆盖:

containsValue 在类中 AbstractMap<K,V>

参数:

value - value whose presence in this map is to be tested

返回:

true if this map maps one or more keys to the specified value

抛出:

NullPointerException - if the specified value is null

contains

public boolean contains(Object value)

Legacy method testing if some key maps into the specified value in this table. This method is identical in functionality to containsValue(java.lang.Object), and exists solely to ensure full compatibility with class Hashtable, which supported this method prior to introduction of the Java Collections framework.

参数:

value - a value to search for

返回:

true if and only if some key maps to the value argument in this table as determined by the equals method; false otherwise

抛出:

NullPointerException - if the specified value is null

put

public V put(K key,
             V value)

Maps the specified key to the specified value in this table. Neither the key nor the value can be null.

The value can be retrieved by calling the get method with a key that is equal to the original key.

指定者:

put 在接口中 Map<K,V>

覆盖:

put 在类中 AbstractMap<K,V>

参数:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

返回:

the previous value associated with key, or null if there was no mapping for key

抛出:

NullPointerException - if the specified key or value is null

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>

返回:

the previous value associated with the specified key, or null if there was no mapping for the key

抛出:

NullPointerException - if the specified key or value is null

putAll

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

Copies all of the mappings from the specified map to this one. These mappings replace any mappings that this map had for any of the keys currently in the specified map.

指定者:

putAll 在接口中 Map<K,V>

覆盖:

putAll 在类中 AbstractMap<K,V>

参数:

m - mappings to be stored in this map

remove

public V remove(Object key)

Removes the key (and its corresponding value) from this map. This method does nothing if the key is not in the map.

指定者:

remove 在接口中 Map<K,V>

覆盖:

remove 在类中 AbstractMap<K,V>

参数:

key - the key that needs to be removed

返回:

the previous value associated with key, or null if there was no mapping for key

抛出:

NullPointerException - if the specified key is null

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>

抛出:

NullPointerException - if the specified key is null

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>

抛出:

NullPointerException - if any of the arguments are null

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>

返回:

the previous value associated with the specified key, or null if there was no mapping for the key

抛出:

NullPointerException - if the specified key or value is null

clear

public void clear()

Removes all of the mappings from this map.

指定者:

clear 在接口中 Map<K,V>

覆盖:

clear 在类中 AbstractMap<K,V>

purgeStaleEntries

public void purgeStaleEntries()

Removes any stale entries whose keys have been finalized. Use of this method is normally not necessary since stale entries are automatically removed lazily, when blocking operations are required. However, there are some cases where this operation should be performed eagerly, such as cleaning up old references to a ClassLoader in a multi-classloader environment. Note: this method will acquire locks, one at a time, across all segments of this table, so if it is to be used, it should be used sparingly.

keySet

public Set<K> keySet()

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

指定者:

keySet 在接口中 Map<K,V>

覆盖:

keySet 在类中 AbstractMap<K,V>

values

public Collection<V> values()

Returns a Collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from this map, via the Iterator.remove, Collection.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

指定者:

values 在接口中 Map<K,V>

覆盖:

values 在类中 AbstractMap<K,V>

entrySet

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

Returns a Set view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

The view's iterator is a "weakly consistent" iterator that will never throw ConcurrentModificationException, and guarantees to traverse elements as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect any modifications subsequent to construction.

指定者:

entrySet 在接口中 Map<K,V>

指定者:

entrySet 在类中 AbstractMap<K,V>

keys

public Enumeration<K> keys()

Returns an enumeration of the keys in this table.

返回:

an enumeration of the keys in this table

另请参阅:

keySet()

elements

public Enumeration<V> elements()

Returns an enumeration of the values in this table.

返回:

an enumeration of the values in this table

另请参阅:

values()