ConcurrentSkipListMap

java.lang.Object
- java.util.AbstractMap<K,V>
- - java.util.concurrent.ConcurrentSkipListMap<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:

Serializable, Cloneable, ConcurrentMap<K,V>, ConcurrentNavigableMap<K,V>, Map<K,V>, NavigableMap<K,V>, SortedMap<K,V>
```
public class ConcurrentSkipListMap<K,V>
extends AbstractMap<K,V>
implements ConcurrentNavigableMap<K,V>, Cloneable, Serializable
```
A scalable concurrent ConcurrentNavigableMap implementation. The map is sorted according to the Comparable of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.
This class implements a concurrent variant of SkipLists providing expected average log(n) time cost for the containsKey, get, put and remove operations and their variants. Insertion, removal, update, and access operations safely execute concurrently by multiple threads.
Iterators and spliterators are weakly consistent.
Ascending key ordered views and their iterators are faster than descending ones.
All Map.Entry pairs returned by methods in this class and its views represent snapshots of mappings at the time they were produced. They do not support the Entry.setValue method. (Note however that it is possible to change mappings in the associated map using put, putIfAbsent, or replace, depending on exactly which effect you need.)
Beware that, unlike in most collections, the size method is not a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires a traversal of the elements, and so may report inaccurate results if this collection is modified during traversal. Additionally, the bulk operations putAll, equals, toArray, containsValue, and clear are not guaranteed to be performed atomically. For example, an iterator operating concurrently with a putAll operation might view only some of the added elements.
This class and its views and iterators implement all of the optional methods of the Map and Iterator interfaces. Like most other concurrent collections, this class does not permit the use of null keys or values because some null return values cannot be reliably distinguished from the absence of elements.
This class is a member of the Java Collections Framework.

从以下版本开始:

1.6

另请参阅:

序列化表格

嵌套类概要
- 从类继承的嵌套类/接口 java.util.AbstractMap
  AbstractMap.SimpleEntry<K,V>, 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	说明
`ConcurrentSkipListMap()`	Constructs a new, empty map, sorted according to the Comparable of the keys.
`ConcurrentSkipListMap(Comparator<? super K> comparator)`	Constructs a new, empty map, sorted according to the specified comparator.
`ConcurrentSkipListMap(Map<? extends K,? extends V> m)`	Constructs a new map containing the same mappings as the given map, sorted according to the Comparable of the keys.
`ConcurrentSkipListMap(SortedMap<K,? extends V> m)`	Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`Map.Entry<K,V>`	`ceilingEntry(K key)`	Returns a key-value mapping associated with the least key greater than or equal to the given key, or `null` if there is no such entry.
`K`	`ceilingKey(K key)`	Returns the least key greater than or equal to the given key, or `null` if there is no such key.
`void`	`clear()`	Removes all of the mappings from this map.
`ConcurrentSkipListMap<K,V>`	`clone()`	Returns a shallow copy of this `ConcurrentSkipListMap` instance.
`Comparator<? super K>`	`comparator()`	Returns the comparator used to order the keys in this map, or `null` if this map uses the Comparable of its keys.
`V`	`compute(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)`	Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping).
`V`	`computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction)`	If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless `null`.
`V`	`computeIfPresent(K key, BiFunction<? super K,? super V,? extends V> remappingFunction)`	If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
`boolean`	`containsKey(Object key)`	Returns `true` if this map contains a mapping for the specified key.
`boolean`	`containsValue(Object value)`	Returns `true` if this map maps one or more keys to the specified value.
`NavigableSet<K>`	`descendingKeySet()`	Returns a reverse order `NavigableSet` view of the keys contained in this map.
`ConcurrentNavigableMap<K,V>`	`descendingMap()`	Returns a reverse order view of the mappings contained in this map.
`Set<Map.Entry<K,V>>`	`entrySet()`	Returns a `Set` view of the mappings contained in this map.
`boolean`	`equals(Object o)`	Compares the specified object with this map for equality.
`Map.Entry<K,V>`	`firstEntry()`	Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
`K`	`firstKey()`	Returns the first (lowest) key currently in this map.
`Map.Entry<K,V>`	`floorEntry(K key)`	Returns a key-value mapping associated with the greatest key less than or equal to the given key, or `null` if there is no such key.
`K`	`floorKey(K key)`	Returns the greatest key less than or equal to the given key, or `null` if there is no such key.
`void`	`forEach(BiConsumer<? super K,? super V> action)`	Performs the given action for each entry in this map until all entries have been processed or the action throws an exception.
`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.
`V`	`getOrDefault(Object key, V defaultValue)`	Returns the value to which the specified key is mapped, or the given defaultValue if this map contains no mapping for the key.
`ConcurrentNavigableMap<K,V>`	`headMap(K toKey)`	Returns a view of the portion of this map whose keys are strictly less than `toKey`.
`ConcurrentNavigableMap<K,V>`	`headMap(K toKey, boolean inclusive)`	Returns a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`.
`Map.Entry<K,V>`	`higherEntry(K key)`	Returns a key-value mapping associated with the least key strictly greater than the given key, or `null` if there is no such key.
`K`	`higherKey(K key)`	Returns the least key strictly greater than the given key, or `null` if there is no such key.
`boolean`	`isEmpty()`	Returns `true` if this map contains no key-value mappings.
`NavigableSet<K>`	`keySet()`	Returns a `NavigableSet` view of the keys contained in this map.
`Map.Entry<K,V>`	`lastEntry()`	Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
`K`	`lastKey()`	Returns the last (highest) key currently in this map.
`Map.Entry<K,V>`	`lowerEntry(K key)`	Returns a key-value mapping associated with the greatest key strictly less than the given key, or `null` if there is no such key.
`K`	`lowerKey(K key)`	Returns the greatest key strictly less than the given key, or `null` if there is no such key.
`V`	`merge(K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction)`	If the specified key is not already associated with a value, associates it with the given value.
`NavigableSet<K>`	`navigableKeySet()`	Returns a `NavigableSet` view of the keys contained in this map.
`Map.Entry<K,V>`	`pollFirstEntry()`	Removes and returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
`Map.Entry<K,V>`	`pollLastEntry()`	Removes and returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
`V`	`put(K key, V value)`	Associates the specified value with the specified key in this map.
`V`	`putIfAbsent(K key, V value)`	If the specified key is not already associated with a value, associate it with the given value.
`V`	`remove(Object key)`	Removes the mapping for the specified key from this map if present.
`boolean`	`remove(Object key, Object value)`	Removes the entry for a key only if currently mapped to a given value.
`V`	`replace(K key, V value)`	Replaces the entry for a key only if currently mapped to some value.
`boolean`	`replace(K key, V oldValue, V newValue)`	Replaces the entry for a key only if currently mapped to a given value.
`void`	`replaceAll(BiFunction<? super K,? super V,? extends V> function)`	Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception.
`int`	`size()`	Returns the number of key-value mappings in this map.
`ConcurrentNavigableMap<K,V>`	`subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)`	Returns a view of the portion of this map whose keys range from `fromKey` to `toKey`.
`ConcurrentNavigableMap<K,V>`	`subMap(K fromKey, K toKey)`	Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive.
`ConcurrentNavigableMap<K,V>`	`tailMap(K fromKey)`	Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`.
`ConcurrentNavigableMap<K,V>`	`tailMap(K fromKey, boolean inclusive)`	Returns a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`.
`Collection<V>`	`values()`	Returns a `Collection` view of the values contained in this map.

从类继承的方法 java.util.AbstractMap
hashCode, putAll, toString

从接口继承的方法 java.util.Map
hashCode, putAll

从类继承的方法 java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

- 构造器详细资料
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap()
```
    Constructs a new, empty map, sorted according to the Comparable of the keys.
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap(Comparator<? super K> comparator)
```
    Constructs a new, empty map, sorted according to the specified comparator.
    
    参数:
    
    comparator - the comparator that will be used to order this map. If null, the Comparable of the keys will be used.
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap(Map<? extends K,? extends V> m)
```
    Constructs a new map containing the same mappings as the given map, sorted according to the Comparable of the keys.
    
    参数:
    
    m - the map whose mappings are to be placed in this map
    
    抛出:
    
    ClassCastException - if the keys in m are not Comparable, or are not mutually comparable
    
    NullPointerException - if the specified map or any of its keys or values are null
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap(SortedMap<K,? extends V> m)
```
    Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.
    
    参数:
    
    m - the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map
    
    抛出:
    
    NullPointerException - if the specified sorted map or any of its keys or values are null
- 方法详细资料
  - clone
```
public ConcurrentSkipListMap<K,V> clone()
```
    Returns a shallow copy of this ConcurrentSkipListMap instance. (The keys and values themselves are not cloned.)
    
    覆盖:
    
    clone 在类中 AbstractMap<K,V>
    
    返回:
    
    a shallow copy of this map
    
    另请参阅:
    
    Cloneable
  - containsKey
```
public boolean containsKey(Object key)
```
    Returns true if this map contains a mapping for the specified key.
    
    指定者:
    
    containsKey 在接口中 Map<K,V>
    
    覆盖:
    
    containsKey 在类中 AbstractMap<K,V>
    
    参数:
    
    key - key whose presence in this map is to be tested
    
    返回:
    
    true if this map contains a mapping for the specified key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - 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 compares equal to k according to the map's ordering, 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>
    
    参数:
    
    key - the key whose associated value is to be returned
    
    返回:
    
    the value to which the specified key is mapped, or null if this map contains no mapping for the key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - getOrDefault
```
public V getOrDefault(Object key,
                      V defaultValue)
```
    Returns the value to which the specified key is mapped, or the given defaultValue if this map contains no mapping for the key.
    
    指定者:
    
    getOrDefault 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    getOrDefault 在接口中 Map<K,V>
    
    参数:
    
    key - the key
    
    defaultValue - the value to return if this map contains no mapping for the given key
    
    返回:
    
    the mapping for the key, if present; else the defaultValue
    
    抛出:
    
    NullPointerException - if the specified key is null
    
    从以下版本开始:
    
    1.8
  - put
```
public V put(K key,
             V value)
```
    Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced.
    
    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 the specified key, or null if there was no mapping for the key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key or value is null
  - remove
```
public V remove(Object key)
```
    Removes the mapping for the specified key from this map if present.
    
    指定者:
    
    remove 在接口中 Map<K,V>
    
    覆盖:
    
    remove 在类中 AbstractMap<K,V>
    
    参数:
    
    key - key for which mapping should be removed
    
    返回:
    
    the previous value associated with the specified key, or null if there was no mapping for the key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    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. This operation requires time linear in the map size. Additionally, it is possible for the map to change during execution of this method, in which case the returned result may be inaccurate.
    
    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 a mapping to value exists; false otherwise
    
    抛出:
    
    NullPointerException - if the specified value is null
  - size
```
public int size()
```
    Returns the number of key-value mappings in this map. If this map contains more than Integer.MAX_VALUE elements, it returns Integer.MAX_VALUE.
    Beware that, unlike in most collections, this method is NOT a constant-time operation. Because of the asynchronous nature of these maps, determining the current number of elements requires traversing them all to count them. Additionally, it is possible for the size to change during execution of this method, in which case the returned result will be inaccurate. Thus, this method is typically not very useful in concurrent applications.
    
    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 elements in this map
  - 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
  - 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>
  - computeIfAbsent
```
public V computeIfAbsent(K key,
                         Function<? super K,? extends V> mappingFunction)
```
    If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless null. The function is NOT guaranteed to be applied once atomically only if the value is not present.
    
    指定者:
    
    computeIfAbsent 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    computeIfAbsent 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is to be associated
    
    mappingFunction - the function to compute a value
    
    返回:
    
    the current (existing or computed) value associated with the specified key, or null if the computed value is null
    
    抛出:
    
    NullPointerException - if the specified key is null or the mappingFunction is null
    
    从以下版本开始:
    
    1.8
  - computeIfPresent
```
public V computeIfPresent(K key,
                          BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value. The function is NOT guaranteed to be applied once atomically.
    
    指定者:
    
    computeIfPresent 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    computeIfPresent 在接口中 Map<K,V>
    
    参数:
    
    key - key with which a value may be associated
    
    remappingFunction - the function to compute a value
    
    返回:
    
    the new value associated with the specified key, or null if none
    
    抛出:
    
    NullPointerException - if the specified key is null or the remappingFunction is null
    
    从以下版本开始:
    
    1.8
  - compute
```
public V compute(K key,
                 BiFunction<? super K,? super V,? extends V> remappingFunction)
```
    Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). The function is NOT guaranteed to be applied once atomically.
    
    指定者:
    
    compute 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    compute 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is to be associated
    
    remappingFunction - the function to compute a value
    
    返回:
    
    the new value associated with the specified key, or null if none
    
    抛出:
    
    NullPointerException - if the specified key is null or the remappingFunction is null
    
    从以下版本开始:
    
    1.8
  - merge
```
public V merge(K key,
               V value,
               BiFunction<? super V,? super V,? extends V> remappingFunction)
```
    If the specified key is not already associated with a value, associates it with the given value. Otherwise, replaces the value with the results of the given remapping function, or removes if null. The function is NOT guaranteed to be applied once atomically.
    
    指定者:
    
    merge 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    merge 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is to be associated
    
    value - the value to use if absent
    
    remappingFunction - the function to recompute a value if present
    
    返回:
    
    the new value associated with the specified key, or null if none
    
    抛出:
    
    NullPointerException - if the specified key or value is null or the remappingFunction is null
    
    从以下版本开始:
    
    1.8
  - keySet
```
public NavigableSet<K> keySet()
```
    Returns a NavigableSet view of the keys contained in this map.
    The set's iterator returns the keys in ascending order. The set's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL, Spliterator#SORTED and Spliterator#ORDERED, with an encounter order that is ascending key order. The spliterator's comparator (see Spliterator.getComparator()) is null if the map's comparator (see comparator()) is null. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the map's comparator.
    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 iterators and spliterators are weakly consistent.
    This method is equivalent to method navigableKeySet.
    
    指定者:
    
    keySet 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    keySet 在接口中 Map<K,V>
    
    指定者:
    
    keySet 在接口中 SortedMap<K,V>
    
    覆盖:
    
    keySet 在类中 AbstractMap<K,V>
    
    返回:
    
    a navigable set view of the keys in this map
  - navigableKeySet
```
public NavigableSet<K> navigableKeySet()
```
    从接口复制的说明: ConcurrentNavigableMap
    
    Returns a NavigableSet view of the keys contained in this map. The set's iterator returns the keys in ascending order. 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 iterators and spliterators are weakly consistent.
    
    指定者:
    
    navigableKeySet 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    navigableKeySet 在接口中 NavigableMap<K,V>
    
    返回:
    
    a navigable set view of the keys in this map
  - values
```
public Collection<V> values()
```
    Returns a Collection view of the values contained in this map.
    The collection's iterator returns the values in ascending order of the corresponding keys. The collections's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL and Spliterator#ORDERED, with an encounter order that is ascending order of the corresponding keys.
    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 the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.
    The view's iterators and spliterators are weakly consistent.
    
    指定者:
    
    values 在接口中 Map<K,V>
    
    指定者:
    
    values 在接口中 SortedMap<K,V>
    
    覆盖:
    
    values 在类中 AbstractMap<K,V>
    
    返回:
    
    a collection view of the values contained in this map
  - entrySet
```
public Set<Map.Entry<K,V>> entrySet()
```
    Returns a Set view of the mappings contained in this map.
    The set's iterator returns the entries in ascending key order. The set's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL, Spliterator#SORTED and Spliterator#ORDERED, with an encounter order that is ascending key order.
    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 iterators and spliterators are weakly consistent.
    The Map.Entry elements traversed by the iterator or spliterator do not support the setValue operation.
    
    指定者:
    
    entrySet 在接口中 Map<K,V>
    
    指定者:
    
    entrySet 在接口中 SortedMap<K,V>
    
    指定者:
    
    entrySet 在类中 AbstractMap<K,V>
    
    返回:
    
    a set view of the mappings contained in this map, sorted in ascending key order
  - descendingMap
```
public ConcurrentNavigableMap<K,V> descendingMap()
```
    从接口复制的说明: ConcurrentNavigableMap
    
    Returns a reverse order view of the mappings contained in this map. The descending map is backed by this map, so changes to the map are reflected in the descending map, and vice-versa.
    The returned map has an ordering equivalent to Collections#reverseOrder(Comparator)(comparator()). The expression m.descendingMap().descendingMap() returns a view of m essentially equivalent to m.
    
    指定者:
    
    descendingMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    descendingMap 在接口中 NavigableMap<K,V>
    
    返回:
    
    a reverse order view of this map
  - descendingKeySet
```
public NavigableSet<K> descendingKeySet()
```
    从接口复制的说明: ConcurrentNavigableMap
    
    Returns a reverse order NavigableSet view of the keys contained in this map. The set's iterator returns the keys in descending order. 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 iterators and spliterators are weakly consistent.
    
    指定者:
    
    descendingKeySet 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    descendingKeySet 在接口中 NavigableMap<K,V>
    
    返回:
    
    a reverse order navigable set view of the keys in this map
  - equals
```
public boolean equals(Object o)
```
    Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This operation may return misleading results if either map is concurrently modified during execution of this method.
    
    指定者:
    
    equals 在接口中 Map<K,V>
    
    覆盖:
    
    equals 在类中 AbstractMap<K,V>
    
    参数:
    
    o - object to be compared for equality with this map
    
    返回:
    
    true if the specified object is equal to this map
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - putIfAbsent
```
public V putIfAbsent(K key,
                     V value)
```
    If the specified key is not already associated with a value, associate it with the given value. This is equivalent to
```
 
 if (!map.containsKey(key))
   return map.put(key, value);
 else
   return map.get(key);
 
```
    except that the action is performed atomically.
    指定者:
    
    putIfAbsent 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    putIfAbsent 在接口中 Map<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 the specified key, or null if there was no mapping for the key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key or value is null
  - remove
```
public boolean remove(Object key,
                      Object value)
```
    Removes the entry for a key only if currently mapped to a given value. This is equivalent to
```
 
 if (map.containsKey(key) && Objects.equals(map.get(key), value)) {
   map.remove(key);
   return true;
 } else
   return false;
 
```
    except that the action is performed atomically.
    指定者:
    
    remove 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    remove 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is associated
    
    value - value expected to be associated with the specified key
    
    返回:
    
    true if the value was removed
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - replace
```
public boolean replace(K key,
                       V oldValue,
                       V newValue)
```
    Replaces the entry for a key only if currently mapped to a given value. This is equivalent to
```
 
 if (map.containsKey(key) && Objects.equals(map.get(key), oldValue)) {
   map.put(key, newValue);
   return true;
 } else
   return false;
 
```
    except that the action is performed atomically.
    指定者:
    
    replace 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    replace 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is associated
    
    oldValue - value expected to be associated with the specified key
    
    newValue - value to be associated with the specified key
    
    返回:
    
    true if the value was replaced
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if any of the arguments are null
  - replace
```
public V replace(K key,
                 V value)
```
    Replaces the entry for a key only if currently mapped to some value. This is equivalent to
```
 
 if (map.containsKey(key)) {
   return map.put(key, value);
 } else
   return null;
 
```
    except that the action is performed atomically.
    指定者:
    
    replace 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    replace 在接口中 Map<K,V>
    
    参数:
    
    key - key with which the specified value is associated
    
    value - value to be associated with the specified key
    
    返回:
    
    the previous value associated with the specified key, or null if there was no mapping for the key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key or value is null
  - comparator
```
public Comparator<? super K> comparator()
```
    从接口复制的说明: SortedMap
    
    Returns the comparator used to order the keys in this map, or null if this map uses the Comparable of its keys.
    
    指定者:
    
    comparator 在接口中 SortedMap<K,V>
    
    返回:
    
    the comparator used to order the keys in this map, or null if this map uses the natural ordering of its keys
  - firstKey
```
public K firstKey()
```
    从接口复制的说明: SortedMap
    
    Returns the first (lowest) key currently in this map.
    
    指定者:
    
    firstKey 在接口中 SortedMap<K,V>
    
    返回:
    
    the first (lowest) key currently in this map
    
    抛出:
    
    NoSuchElementException - if this map is empty
  - lastKey
```
public K lastKey()
```
    从接口复制的说明: SortedMap
    
    Returns the last (highest) key currently in this map.
    
    指定者:
    
    lastKey 在接口中 SortedMap<K,V>
    
    返回:
    
    the last (highest) key currently in this map
    
    抛出:
    
    NoSuchElementException - if this map is empty
  - subMap
```
public ConcurrentNavigableMap<K,V> subMap(K fromKey,
                                          boolean fromInclusive,
                                          K toKey,
                                          boolean toInclusive)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys range from fromKey to toKey. If fromKey and toKey are equal, the returned map is empty unless fromInclusive and toInclusive are both true. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside of its range, or to construct a submap either of whose endpoints lie outside its range.
    
    指定者:
    
    subMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    subMap 在接口中 NavigableMap<K,V>
    
    参数:
    
    fromKey - low endpoint of the keys in the returned map
    
    fromInclusive - true if the low endpoint is to be included in the returned view
    
    toKey - high endpoint of the keys in the returned map
    
    toInclusive - true if the high endpoint is to be included in the returned view
    
    返回:
    
    a view of the portion of this map whose keys range from fromKey to toKey
    
    抛出:
    
    ClassCastException - if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.
    
    NullPointerException - if fromKey or toKey is null
    
    IllegalArgumentException - if fromKey is greater than toKey; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range
  - headMap
```
public ConcurrentNavigableMap<K,V> headMap(K toKey,
                                           boolean inclusive)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) toKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
    
    指定者:
    
    headMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    headMap 在接口中 NavigableMap<K,V>
    
    参数:
    
    toKey - high endpoint of the keys in the returned map
    
    inclusive - true if the high endpoint is to be included in the returned view
    
    返回:
    
    a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) toKey
    
    抛出:
    
    ClassCastException - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
    
    NullPointerException - if toKey is null
    
    IllegalArgumentException - if this map itself has a restricted range, and toKey lies outside the bounds of the range
  - tailMap
```
public ConcurrentNavigableMap<K,V> tailMap(K fromKey,
                                           boolean inclusive)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
    
    指定者:
    
    tailMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    tailMap 在接口中 NavigableMap<K,V>
    
    参数:
    
    fromKey - low endpoint of the keys in the returned map
    
    inclusive - true if the low endpoint is to be included in the returned view
    
    返回:
    
    a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) fromKey
    
    抛出:
    
    ClassCastException - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
    
    NullPointerException - if fromKey is null
    
    IllegalArgumentException - if this map itself has a restricted range, and fromKey lies outside the bounds of the range
  - subMap
```
public ConcurrentNavigableMap<K,V> subMap(K fromKey,
                                          K toKey)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. (If fromKey and toKey are equal, the returned map is empty.) The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
    Equivalent to subMap(fromKey, true, toKey, false).
    
    指定者:
    
    subMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    subMap 在接口中 NavigableMap<K,V>
    
    指定者:
    
    subMap 在接口中 SortedMap<K,V>
    
    参数:
    
    fromKey - low endpoint (inclusive) of the keys in the returned map
    
    toKey - high endpoint (exclusive) of the keys in the returned map
    
    返回:
    
    a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive
    
    抛出:
    
    ClassCastException - if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.
    
    NullPointerException - if fromKey or toKey is null
    
    IllegalArgumentException - if fromKey is greater than toKey; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range
  - headMap
```
public ConcurrentNavigableMap<K,V> headMap(K toKey)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys are strictly less than toKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
    Equivalent to headMap(toKey, false).
    
    指定者:
    
    headMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    headMap 在接口中 NavigableMap<K,V>
    
    指定者:
    
    headMap 在接口中 SortedMap<K,V>
    
    参数:
    
    toKey - high endpoint (exclusive) of the keys in the returned map
    
    返回:
    
    a view of the portion of this map whose keys are strictly less than toKey
    
    抛出:
    
    ClassCastException - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
    
    NullPointerException - if toKey is null
    
    IllegalArgumentException - if this map itself has a restricted range, and toKey lies outside the bounds of the range
  - tailMap
```
public ConcurrentNavigableMap<K,V> tailMap(K fromKey)
```
    从接口复制的说明: NavigableMap
    
    Returns a view of the portion of this map whose keys are greater than or equal to fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
    The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
    Equivalent to tailMap(fromKey, true).
    
    指定者:
    
    tailMap 在接口中 ConcurrentNavigableMap<K,V>
    
    指定者:
    
    tailMap 在接口中 NavigableMap<K,V>
    
    指定者:
    
    tailMap 在接口中 SortedMap<K,V>
    
    参数:
    
    fromKey - low endpoint (inclusive) of the keys in the returned map
    
    返回:
    
    a view of the portion of this map whose keys are greater than or equal to fromKey
    
    抛出:
    
    ClassCastException - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
    
    NullPointerException - if fromKey is null
    
    IllegalArgumentException - if this map itself has a restricted range, and fromKey lies outside the bounds of the range
  - lowerEntry
```
public Map.Entry<K,V> lowerEntry(K key)
```
    Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    lowerEntry 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    an entry with the greatest key less than key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - lowerKey
```
public K lowerKey(K key)
```
    从接口复制的说明: NavigableMap
    
    Returns the greatest key strictly less than the given key, or null if there is no such key.
    
    指定者:
    
    lowerKey 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    the greatest key less than key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - floorEntry
```
public Map.Entry<K,V> floorEntry(K key)
```
    Returns a key-value mapping associated with the greatest key less than or equal to the given key, or null if there is no such key. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    floorEntry 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    an entry with the greatest key less than or equal to key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - floorKey
```
public K floorKey(K key)
```
    从接口复制的说明: NavigableMap
    
    Returns the greatest key less than or equal to the given key, or null if there is no such key.
    
    指定者:
    
    floorKey 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    the greatest key less than or equal to key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - ceilingEntry
```
public Map.Entry<K,V> ceilingEntry(K key)
```
    Returns a key-value mapping associated with the least key greater than or equal to the given key, or null if there is no such entry. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    ceilingEntry 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    an entry with the least key greater than or equal to key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - ceilingKey
```
public K ceilingKey(K key)
```
    从接口复制的说明: NavigableMap
    
    Returns the least key greater than or equal to the given key, or null if there is no such key.
    
    指定者:
    
    ceilingKey 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    the least key greater than or equal to key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - higherEntry
```
public Map.Entry<K,V> higherEntry(K key)
```
    Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    higherEntry 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    an entry with the least key greater than key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - higherKey
```
public K higherKey(K key)
```
    从接口复制的说明: NavigableMap
    
    Returns the least key strictly greater than the given key, or null if there is no such key.
    
    指定者:
    
    higherKey 在接口中 NavigableMap<K,V>
    
    参数:
    
    key - the key
    
    返回:
    
    the least key greater than key, or null if there is no such key
    
    抛出:
    
    ClassCastException - if the specified key cannot be compared with the keys currently in the map
    
    NullPointerException - if the specified key is null
  - firstEntry
```
public Map.Entry<K,V> firstEntry()
```
    Returns a key-value mapping associated with the least key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    firstEntry 在接口中 NavigableMap<K,V>
    
    返回:
    
    an entry with the least key, or null if this map is empty
  - lastEntry
```
public Map.Entry<K,V> lastEntry()
```
    Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    lastEntry 在接口中 NavigableMap<K,V>
    
    返回:
    
    an entry with the greatest key, or null if this map is empty
  - pollFirstEntry
```
public Map.Entry<K,V> pollFirstEntry()
```
    Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    pollFirstEntry 在接口中 NavigableMap<K,V>
    
    返回:
    
    the removed first entry of this map, or null if this map is empty
  - pollLastEntry
```
public Map.Entry<K,V> pollLastEntry()
```
    Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. The returned entry does not support the Entry.setValue method.
    
    指定者:
    
    pollLastEntry 在接口中 NavigableMap<K,V>
    
    返回:
    
    the removed last entry of this map, or null if this map is empty
  - forEach
```
public void forEach(BiConsumer<? super K,? super V> action)
```
    从接口复制的说明: ConcurrentMap
    
    Performs the given action for each entry in this map until all entries have been processed or the action throws an exception. Unless otherwise specified by the implementing class, actions are performed in the order of entry set iteration (if an iteration order is specified.) Exceptions thrown by the action are relayed to the caller.
    
    指定者:
    
    forEach 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    forEach 在接口中 Map<K,V>
    
    参数:
    
    action - The action to be performed for each entry
  - replaceAll
```
public void replaceAll(BiFunction<? super K,? super V,? extends V> function)
```
    从接口复制的说明: ConcurrentMap
    
    Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. Exceptions thrown by the function are relayed to the caller.
    
    指定者:
    
    replaceAll 在接口中 ConcurrentMap<K,V>
    
    指定者:
    
    replaceAll 在接口中 Map<K,V>
    
    参数:
    
    function - the function to apply to each entry

类 ConcurrentSkipListMap<K,V>

嵌套类概要

从类继承的嵌套类/接口 java.util.AbstractMap

从接口继承的嵌套类/接口 java.util.Map

构造器概要

方法概要

从类继承的方法 java.util.AbstractMap

从接口继承的方法 java.util.Map

从类继承的方法 java.lang.Object

构造器详细资料

ConcurrentSkipListMap

ConcurrentSkipListMap

ConcurrentSkipListMap

ConcurrentSkipListMap

方法详细资料

clone

containsKey

get

getOrDefault

put

remove

containsValue

size

isEmpty

clear

computeIfAbsent

computeIfPresent

compute

merge

keySet

navigableKeySet

values

entrySet

descendingMap

descendingKeySet

equals

putIfAbsent

remove

replace

replace

comparator

firstKey

lastKey

subMap

headMap

tailMap

subMap

headMap

tailMap

lowerEntry

lowerKey

floorEntry

floorKey

ceilingEntry

ceilingKey

higherEntry

higherKey

firstEntry

lastEntry

pollFirstEntry

pollLastEntry

forEach

replaceAll