ConcurrentSkipListMap

java.lang.Object
- java.util.AbstractMap<K,V>
- - jsr166x.ConcurrentSkipListMap<K,V>

Type Parameters:
K - the type of keys maintained by this map
V - the type of mapped values

All Implemented Interfaces:

Serializable, Cloneable, ConcurrentMap<K,V>, Map<K,V>, SortedMap<K,V>, ConcurrentNavigableMap<K,V>, NavigableMap<K,V>
```
public class ConcurrentSkipListMap<K,V>
extends AbstractMap<K,V>
implements ConcurrentNavigableMap<K,V>, Cloneable, Serializable
```
A scalable ConcurrentNavigableMap implementation. This class maintains a map in ascending key order, sorted according to the natural order for the key's class (see Comparable), or by the Comparator provided at 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 are weakly consistent, returning elements reflecting the state of the map at some point at or since the creation of the iterator. They do not throw ConcurrentModificationException, and may proceed concurrently with other operations. 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. Additionally, the bulk operations putAll, equals, 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.

Author:

Doug Lea

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 and Description
`ConcurrentSkipListMap()` Constructs a new empty map, sorted according to the keys' natural order.
`ConcurrentSkipListMap(Comparator<? super K> c)` Constructs a new empty map, sorted according to the given comparator.
`ConcurrentSkipListMap(Map<? extends K,? extends V> m)` Constructs a new map containing the same mappings as the given map, sorted according to the keys' natural order.
`ConcurrentSkipListMap(SortedMap<K,? extends V> m)` Constructs a new map containing the same mappings as the given `SortedMap`, sorted according to the same ordering.

Method Summary

Methods
Modifier and Type	Method and Description
`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 least key greater than or equal to the given key, or `null` if there is no such key.
`void`	`clear()` Removes all mappings from this map.
`Object`	`clone()` Returns a shallow copy of this `Map` instance.
`Comparator<? super K>`	`comparator()` Returns the comparator used to order this map, or `null` if this map uses its keys' natural order.
`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.
`Set<Map.Entry<K,V>>`	`descendingEntrySet()` Returns a collection view of the mappings contained in this map, in descending order.
`Set<K>`	`descendingKeySet()` Returns a set view of the keys contained in this map in descending order.
`Set<Map.Entry<K,V>>`	`entrySet()` Returns a collection 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 entry.
`K`	`floorKey(K key)` Returns the greatest key less than or equal to the given key, or `null` if there is no such key.
`V`	`get(Object key)` Returns the value to which this map maps the specified key.
`ConcurrentNavigableMap<K,V>`	`headMap(K toKey)` Returns a view of the portion of this map whose keys are strictly less than `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 entry.
`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.
`Set<K>`	`keySet()` Returns a set 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 entry.
`K`	`lowerKey(K key)` Returns the greatest key strictly less than the given key, or `null` if there is no such key.
`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 this key from this Map if present.
`boolean`	`remove(Object key, Object value)` Removes entry for key only if currently mapped to given value.
`V`	`replace(K key, V value)` Replaces entry for key only if currently mapped to some value.
`boolean`	`replace(K key, V oldValue, V newValue)` Replaces entry for key only if currently mapped to given value.
`int`	`size()` Returns the number of elements in this map.
`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`.
`Collection<V>`	`values()` Returns a collection view of the values contained in this map.

Methods inherited from class java.util.AbstractMap
hashCode, putAll, toString

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Map
hashCode, putAll

- Constructor Detail
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap()
```
    Constructs a new empty map, sorted according to the keys' natural order.
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap(Comparator<? super K> c)
```
    Constructs a new empty map, sorted according to the given comparator.
    
    Parameters:
    c - the comparator that will be used to sort this map. A null value indicates that the keys' natural ordering should 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 keys' natural order.
    
    Parameters:
    m - the map whose mappings are to be placed in this map
    
    Throws:
    
    ClassCastException - if the keys in m are not Comparable, or are not mutually comparable
    
    NullPointerException - if the specified map is null
  - ConcurrentSkipListMap
```
public ConcurrentSkipListMap(SortedMap<K,? extends V> m)
```
    Constructs a new map containing the same mappings as the given SortedMap, sorted according to the same ordering.
    
    Parameters:
    m - the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map
    
    Throws:
    
    NullPointerException - if the specified sorted map is null
- Method Detail
  - clone
```
public Object clone()
```
    Returns a shallow copy of this Map instance. (The keys and values themselves are not cloned.)
    
    Overrides:
    
    clone in class AbstractMap<K,V>
    
    Returns:
    a shallow copy of this Map
  - containsKey
```
public boolean containsKey(Object key)
```
    Returns true if this map contains a mapping for the specified key.
    
    Specified by:
    
    containsKey in interface Map<K,V>
    
    Overrides:
    
    containsKey in class AbstractMap<K,V>
    
    Parameters:
    key - key whose presence in this map is to be tested
    
    Returns:
    true if this map contains a mapping for the specified key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key is null
  - get
```
public V get(Object key)
```
    Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key.
    
    Specified by:
    
    get in interface Map<K,V>
    
    Overrides:
    
    get in class AbstractMap<K,V>
    
    Parameters:
    key - key whose associated value is to be returned
    
    Returns:
    the value to which this map maps the specified key, or null if the map contains no mapping for the key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key is null
  - 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 this key, the old value is replaced.
    
    Specified by:
    
    put in interface Map<K,V>
    
    Overrides:
    
    put in class AbstractMap<K,V>
    
    Parameters:
    key - key with which the specified value is to be associated
    value - value to be associated with the specified key
    
    Returns:
    previous value associated with specified key, or null if there was no mapping for key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key or value are null
  - remove
```
public V remove(Object key)
```
    Removes the mapping for this key from this Map if present.
    
    Specified by:
    
    remove in interface Map<K,V>
    
    Overrides:
    
    remove in class AbstractMap<K,V>
    
    Parameters:
    key - key for which mapping should be removed
    
    Returns:
    previous value associated with specified key, or null if there was no mapping for key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the 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.
    
    Specified by:
    
    containsValue in interface Map<K,V>
    
    Overrides:
    
    containsValue in class AbstractMap<K,V>
    
    Parameters:
    value - value whose presence in this Map is to be tested
    
    Returns:
    true if a mapping to value exists; false otherwise
    
    Throws:
    
    NullPointerException - if the value is null
  - size
```
public int size()
```
    Returns the number of elements 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.
    
    Specified by:
    
    size in interface Map<K,V>
    
    Overrides:
    
    size in class AbstractMap<K,V>
    
    Returns:
    the number of elements in this map
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if this map contains no key-value mappings.
    
    Specified by:
    
    isEmpty in interface Map<K,V>
    
    Overrides:
    
    isEmpty in class AbstractMap<K,V>
    
    Returns:
    true if this map contains no key-value mappings
  - clear
```
public void clear()
```
    Removes all mappings from this map.
    
    Specified by:
    
    clear in interface Map<K,V>
    
    Overrides:
    
    clear in class AbstractMap<K,V>
  - 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.
    
    Specified by:
    
    keySet in interface Map<K,V>
    
    Specified by:
    
    keySet in interface SortedMap<K,V>
    
    Overrides:
    
    keySet in class AbstractMap<K,V>
    
    Returns:
    a set view of the keys contained in this map
  - descendingKeySet
```
public Set<K> descendingKeySet()
```
    Returns a set view of the keys contained in this map 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 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.
    
    Specified by:
    
    descendingKeySet in interface NavigableMap<K,V>
    
    Returns:
    a set view of the keys contained in this map
  - 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.
    
    Specified by:
    
    values in interface Map<K,V>
    
    Specified by:
    
    values in interface SortedMap<K,V>
    
    Overrides:
    
    values in class AbstractMap<K,V>
    
    Returns:
    a collection view of the values contained in this map
  - entrySet
```
public Set<Map.Entry<K,V>> entrySet()
```
    Returns a collection view of the mappings contained in this map. Each element in the returned collection is a Map.Entry. 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 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. The Map.Entry elements returned by iterator.next() do not support the setValue operation.
    
    Specified by:
    
    entrySet in interface Map<K,V>
    
    Specified by:
    
    entrySet in interface SortedMap<K,V>
    
    Specified by:
    
    entrySet in class AbstractMap<K,V>
    
    Returns:
    a collection view of the mappings contained in this map
  - descendingEntrySet
```
public Set<Map.Entry<K,V>> descendingEntrySet()
```
    Returns a collection view of the mappings contained in this map, in descending order. Each element in the returned collection is a Map.Entry. 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 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. The Map.Entry elements returned by iterator.next() do not support the setValue operation.
    
    Specified by:
    
    descendingEntrySet in interface NavigableMap<K,V>
    
    Returns:
    a collection view of the mappings contained 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 t1 and t2 represent the same mappings if t1.keySet().equals(t2.keySet()) and for every key k in t1.keySet(), (t1.get(k)==null ? t2.get(k)==null : t1.get(k).equals(t2.get(k))). This operation may return misleading results if either map is concurrently modified during execution of this method.
    
    Specified by:
    
    equals in interface Map<K,V>
    
    Overrides:
    
    equals in class AbstractMap<K,V>
    
    Parameters:
    o - object to be compared for equality with this map
    
    Returns:
    true if the specified object is equal to this map
  - 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.
    Specified by:
    
    putIfAbsent in interface ConcurrentMap<K,V>
    
    Parameters:
    key - key with which the specified value is to be associated
    value - value to be associated with the specified key
    
    Returns:
    previous value associated with specified key, or null if there was no mapping for key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key or value are null
  - remove
```
public boolean remove(Object key,
             Object value)
```
    Removes entry for key only if currently mapped to given value. Acts as
```
  if ((map.containsKey(key) && map.get(key).equals(value)) {
     map.remove(key);
     return true;
 } else return false;
 
```
    except that the action is performed atomically.
    Specified by:
    
    remove in interface ConcurrentMap<K,V>
    
    Parameters:
    key - key with which the specified value is associated
    value - value associated with the specified key
    
    Returns:
    true if the value was removed, false otherwise
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key or value are null
  - replace
```
public boolean replace(K key,
              V oldValue,
              V newValue)
```
    Replaces entry for key only if currently mapped to given value. Acts as
```
  if ((map.containsKey(key) && map.get(key).equals(oldValue)) {
     map.put(key, newValue);
     return true;
 } else return false;
 
```
    except that the action is performed atomically.
    Specified by:
    
    replace in interface ConcurrentMap<K,V>
    
    Parameters:
    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
    
    Returns:
    true if the value was replaced
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if key, oldValue or newValue are null
  - replace
```
public V replace(K key,
        V value)
```
    Replaces entry for key only if currently mapped to some value. Acts as
```
  if ((map.containsKey(key)) {
     return map.put(key, value);
 } else return null;
 
```
    except that the action is performed atomically.
    Specified by:
    
    replace in interface ConcurrentMap<K,V>
    
    Parameters:
    key - key with which the specified value is associated
    value - value to be associated with the specified key
    
    Returns:
    previous value associated with specified key, or null if there was no mapping for key
    
    Throws:
    
    ClassCastException - if the key cannot be compared with the keys currently in the map
    
    NullPointerException - if the key or value are null
  - comparator
```
public Comparator<? super K> comparator()
```
    Returns the comparator used to order this map, or null if this map uses its keys' natural order.
    
    Specified by:
    
    comparator in interface SortedMap<K,V>
    
    Returns:
    the comparator associated with this map, or null if it uses its keys' natural sort method
  - firstKey
```
public K firstKey()
```
    Returns the first (lowest) key currently in this map.
    
    Specified by:
    
    firstKey in interface SortedMap<K,V>
    
    Returns:
    the first (lowest) key currently in this map
    
    Throws:
    
    NoSuchElementException - Map is empty
  - lastKey
```
public K lastKey()
```
    Returns the last (highest) key currently in this map.
    
    Specified by:
    
    lastKey in interface SortedMap<K,V>
    
    Returns:
    the last (highest) key currently in this map
    
    Throws:
    
    NoSuchElementException - Map is empty
  - subMap
```
public 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. (If fromKey and toKey are equal, the returned sorted map is empty.) The returned sorted map is backed by this map, so changes in the returned sorted map are reflected in this map, and vice-versa.
    
    Specified by:
    
    subMap in interface SortedMap<K,V>
    
    Specified by:
    
    subMap in interface ConcurrentNavigableMap<K,V>
    
    Specified by:
    
    subMap in interface NavigableMap<K,V>
    
    Parameters:
    fromKey - low endpoint (inclusive) of the subMap
    toKey - high endpoint (exclusive) of the subMap
    
    Returns:
    a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive
    
    Throws:
    
    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)
    
    IllegalArgumentException - if fromKey is greater than toKey
    
    NullPointerException - if fromKey or toKey is null
  - headMap
```
public ConcurrentNavigableMap<K,V> headMap(K toKey)
```
    Returns a view of the portion of this map whose keys are strictly less than toKey. The returned sorted map is backed by this map, so changes in the returned sorted map are reflected in this map, and vice-versa.
    
    Specified by:
    
    headMap in interface SortedMap<K,V>
    
    Specified by:
    
    headMap in interface ConcurrentNavigableMap<K,V>
    
    Specified by:
    
    headMap in interface NavigableMap<K,V>
    
    Parameters:
    toKey - high endpoint (exclusive) of the headMap
    
    Returns:
    a view of the portion of this map whose keys are strictly less than toKey
    
    Throws:
    
    ClassCastException - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable)
    
    NullPointerException - if toKey is null
  - tailMap
```
public ConcurrentNavigableMap<K,V> tailMap(K fromKey)
```
    Returns a view of the portion of this map whose keys are greater than or equal to fromKey. The returned sorted map is backed by this map, so changes in the returned sorted map are reflected in this map, and vice-versa.
    
    Specified by:
    
    tailMap in interface SortedMap<K,V>
    
    Specified by:
    
    tailMap in interface ConcurrentNavigableMap<K,V>
    
    Specified by:
    
    tailMap in interface NavigableMap<K,V>
    
    Parameters:
    fromKey - low endpoint (inclusive) of the tailMap
    
    Returns:
    a view of the portion of this map whose keys are greater than or equal to fromKey
    
    Throws:
    
    ClassCastException - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable)
    
    NullPointerException - if fromKey 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.
    
    Specified by:
    
    ceilingEntry in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    an Entry associated with ceiling of given key, or null if there is no such Entry
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if key is null
  - ceilingKey
```
public K ceilingKey(K key)
```
    Returns least key greater than or equal to the given key, or null if there is no such key.
    
    Specified by:
    
    ceilingKey in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    the ceiling key, or null if there is no such key
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if key is null
  - 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 entry. The returned entry does not support the Entry.setValue method.
    
    Specified by:
    
    lowerEntry in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    an Entry with greatest key less than the given key, or null if there is no such Entry
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if key is null
  - lowerKey
```
public K lowerKey(K key)
```
    Returns the greatest key strictly less than the given key, or null if there is no such key.
    
    Specified by:
    
    lowerKey in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    the greatest key less than the given key, or null if there is no such key
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if 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 entry. The returned entry does not support the Entry.setValue method.
    
    Specified by:
    
    floorEntry in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    an Entry associated with floor of given key, or null if there is no such Entry
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if key is null
  - floorKey
```
public K floorKey(K key)
```
    Returns the greatest key less than or equal to the given key, or null if there is no such key.
    
    Specified by:
    
    floorKey in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    the floor of given key, or null if there is no such key
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if 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 entry. The returned entry does not support the Entry.setValue method.
    
    Specified by:
    
    higherEntry in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    an Entry with least key greater than the given key, or null if there is no such Entry
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if key is null
  - higherKey
```
public K higherKey(K key)
```
    Returns the least key strictly greater than the given key, or null if there is no such key.
    
    Specified by:
    
    higherKey in interface NavigableMap<K,V>
    
    Parameters:
    key - the key
    
    Returns:
    the least key greater than the given key, or null if there is no such key
    
    Throws:
    
    ClassCastException - if key cannot be compared with the keys currently in the map
    
    NullPointerException - if 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.
    
    Specified by:
    
    firstEntry in interface NavigableMap<K,V>
    
    Returns:
    an Entry with least key, or null if the 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.
    
    Specified by:
    
    lastEntry in interface NavigableMap<K,V>
    
    Returns:
    an Entry with greatest key, or null if the 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.
    
    Specified by:
    
    pollFirstEntry in interface NavigableMap<K,V>
    
    Returns:
    the removed first entry of this map, or null if the 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.
    
    Specified by:
    
    pollLastEntry in interface NavigableMap<K,V>
    
    Returns:
    the removed last entry of this map, or null if the map is empty

Class ConcurrentSkipListMap<K,V>

Nested Class Summary

Nested classes/interfaces inherited from class java.util.AbstractMap

Nested classes/interfaces inherited from interface java.util.Map

Constructor Summary

Method Summary

Methods inherited from class java.util.AbstractMap

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Map

Constructor Detail

ConcurrentSkipListMap

ConcurrentSkipListMap

ConcurrentSkipListMap

ConcurrentSkipListMap

Method Detail

clone

containsKey

get

put

remove

containsValue

size

isEmpty

clear

keySet

descendingKeySet

values

entrySet

descendingEntrySet

equals

putIfAbsent

remove

replace

replace

comparator

firstKey

lastKey

subMap

headMap

tailMap

ceilingEntry

ceilingKey

lowerEntry

lowerKey

floorEntry

floorKey

higherEntry

higherKey

firstEntry

lastEntry

pollFirstEntry

pollLastEntry