java.lang.Object | ||
↳ | java.util.AbstractMap<K, V> | |
↳ | java.util.concurrent.ConcurrentSkipListMap<K, V> |
A scalable concurrent ConcurrentNavigableMap
implementation.
The map is sorted according to the natural
ordering
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 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.
This class is a member of the Java Collections Framework.
Public Constructors | |||||||||||
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Constructs a new, empty map, sorted according to the
natural ordering of the keys. | |||||||||||
Constructs a new, empty map, sorted according to the specified
comparator.
| |||||||||||
Constructs a new map containing the same mappings as the given map,
sorted according to the
natural ordering of
the keys. | |||||||||||
Constructs a new map containing the same mappings and using the
same ordering as the specified sorted map.
|
Public Methods | |||||||||||
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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.
| |||||||||||
Returns the smallest key greater than or equal to the specified key, or
null if no such key.
| |||||||||||
Removes all of the mappings from this map.
| |||||||||||
Returns a shallow copy of this ConcurrentSkipListMap
instance.
| |||||||||||
Returns the comparator used to compare keys in this sorted map.
| |||||||||||
Returns true if this map contains a mapping for the specified
key.
| |||||||||||
Returns true if this map maps one or more keys to the
specified value.
| |||||||||||
Returns a reverse order
NavigableSet view of the keys contained in this map. | |||||||||||
Returns a reverse order view of the mappings contained in this map.
| |||||||||||
Returns a
Set view of the mappings contained in this map. | |||||||||||
Compares the specified object with this map for equality.
| |||||||||||
Returns a key-value mapping associated with the least
key in this map, or null if the map is empty.
| |||||||||||
Returns the first key in this sorted map.
| |||||||||||
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.
| |||||||||||
Returns the biggest key less than or equal to the specified key, or null
if no such key.
| |||||||||||
Returns the value to which the specified key is mapped,
or
null if this map contains no mapping for the key. | |||||||||||
Returns a view of the head of the map whose keys are smaller than (or
equal to, depends on inclusive argument) endKey.
| |||||||||||
Returns a sorted map over a range of this sorted map with all keys that
are less than the specified
endKey . | |||||||||||
Returns a key-value mapping associated with the least key
strictly greater than the given key, or null if there
is no such key.
| |||||||||||
Returns the smallest key greater than the specified key, or null if no
such key.
| |||||||||||
Returns true if this map contains no key-value mappings.
| |||||||||||
Returns a
NavigableSet view of the keys contained in this map. | |||||||||||
Returns a key-value mapping associated with the greatest
key in this map, or null if the map is empty.
| |||||||||||
Returns the last key in this sorted map.
| |||||||||||
Returns a key-value mapping associated with the greatest key
strictly less than the given key, or null if there is
no such key.
| |||||||||||
Returns the biggest key less than the specified key, or null if no such
key.
| |||||||||||
Returns a
NavigableSet view of the keys contained in this map. | |||||||||||
Removes and returns a key-value mapping associated with
the least key in this map, or null if the map is empty.
| |||||||||||
Removes and returns a key-value mapping associated with
the greatest key in this map, or null if the map is empty.
| |||||||||||
Associates the specified value with the specified key in this map.
| |||||||||||
If the specified key is not already associated
with a value, associate it with the given value.
| |||||||||||
Removes the entry for a key only if currently mapped to a given value.
| |||||||||||
Removes the mapping for the specified key from this map if present.
| |||||||||||
Replaces the entry for a key only if currently mapped to a given value.
| |||||||||||
Replaces the entry for a key only if currently mapped to some value.
| |||||||||||
Returns the number of key-value mappings in this map.
| |||||||||||
Returns a sorted map over a range of this sorted map with all keys
greater than or equal to the specified
startKey and less than the
specified endKey . | |||||||||||
Returns a view of part of the map whose keys is from startKey to endKey.
| |||||||||||
Returns a view of the tail of the map whose keys are bigger than (or
equal to, depends on inclusive argument) startKey.
| |||||||||||
Returns a sorted map over a range of this sorted map with all keys that
are greater than or equal to the specified
startKey . | |||||||||||
Returns a
Collection view of the values contained in this map. |
[Expand]
Inherited Methods | |||||||||||
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From class java.util.AbstractMap
| |||||||||||
From class java.lang.Object
| |||||||||||
From interface java.util.Map
| |||||||||||
From interface java.util.NavigableMap | |||||||||||
From interface java.util.SortedMap
| |||||||||||
From interface java.util.concurrent.ConcurrentMap
| |||||||||||
From interface java.util.concurrent.ConcurrentNavigableMap |
Constructs a new, empty map, sorted according to the
natural ordering
of the keys.
Constructs a new, empty map, sorted according to the specified comparator.
comparator | the comparator that will be used to order this map.
If null, the natural
ordering of the keys will be used.
|
---|
Constructs a new map containing the same mappings as the given map,
sorted according to the natural ordering
of
the keys.
m | the map whose mappings are to be placed in this map |
---|
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 |
Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.
m | the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map |
---|
NullPointerException | if the specified sorted map or any of its keys or values are null |
---|
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.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns the smallest key greater than or equal to the specified key, or null if no such key.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns a shallow copy of this ConcurrentSkipListMap instance. (The keys and values themselves are not cloned.)
Returns the comparator used to compare keys in this sorted map.
null
if the natural order is used.
Returns true if this map contains a mapping for the specified key.
key | key whose presence in this map is to be tested |
---|
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key is null |
Returns true if this map maps one or more keys to the specified value. This operation requires time linear in the map size.
value | value whose presence in this map is to be tested |
---|
NullPointerException | if the specified value is null |
---|
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 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.
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()).
The expression m.descendingMap().descendingMap()
returns a
view of m
essentially equivalent to m
.
Returns a Set
view of the mappings contained in this map.
The set's iterator returns the entries in 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 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.
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.
o | object to be compared for equality with this map |
---|
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.
Returns the first key in this sorted map.
NoSuchElementException |
---|
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.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns the biggest key less than or equal to the specified key, or null if no such key.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
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.)
key | the key. |
---|
null
if no mapping for the specified key is found.
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key is null |
Returns a view of the head of the map whose keys are smaller than (or equal to, depends on inclusive argument) endKey.
toKey | the end key |
---|---|
inclusive | true if the end key is in the returned map |
ClassCastException | |
---|---|
NullPointerException | if toKey is null |
IllegalArgumentException |
Returns a sorted map over a range of this sorted map with all keys that
are less than the specified endKey
. Changes to the returned
sorted map are reflected in this sorted map and vice versa.
Note: The returned map will not allow an insertion of a key outside the specified range.
toKey | the high boundary of the range specified. |
---|
endKey
.ClassCastException | |
---|---|
NullPointerException | if toKey is null |
IllegalArgumentException |
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.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns the smallest key greater than the specified key, or null if no such key.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns true if this map contains no key-value mappings.
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 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.
This method is equivalent to method navigableKeySet
.
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.
Returns the last key in this sorted map.
NoSuchElementException |
---|
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.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
Returns the biggest key less than the specified key, or null if no such key.
key | the key |
---|
ClassCastException | |
---|---|
NullPointerException | if the specified key is null |
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 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.
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.
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.
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.
key | key with which the specified value is to be associated |
---|---|
value | value to be associated with the specified key |
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key or value is null |
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.
key | key with which the specified value is to be associated |
---|---|
value | value to be associated with the specified key |
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key or value is null |
Removes the entry for a key only if currently mapped to a given value. This is equivalent to
if (map.containsKey(key) && map.get(key).equals(value)) { map.remove(key); return true; } else return false;except that the action is performed atomically.
key | key with which the specified value is associated |
---|---|
value | value expected to be associated with the specified key |
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key is null |
Removes the mapping for the specified key from this map if present.
key | key for which mapping should be removed |
---|
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key is null |
Replaces the entry for a key only if currently mapped to a given value. This is equivalent to
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.
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 |
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if any of the arguments are null |
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.
key | key with which the specified value is associated |
---|---|
value | value to be associated with the specified key |
ClassCastException | if the specified key cannot be compared with the keys currently in the map |
---|---|
NullPointerException | if the specified key or value is null |
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.
Returns a sorted map over a range of this sorted map with all keys
greater than or equal to the specified startKey
and less than the
specified endKey
. Changes to the returned sorted map are
reflected in this sorted map and vice versa.
Note: The returned map will not allow an insertion of a key outside the specified range.
fromKey | the low boundary of the range (inclusive). |
---|---|
toKey | the high boundary of the range (exclusive), |
ClassCastException | |
---|---|
NullPointerException | if fromKey or toKey is null |
IllegalArgumentException |
Returns a view of part of the map whose keys is from startKey to endKey.
fromKey | the start key |
---|---|
fromInclusive | true if the start key is in the returned map |
toKey | the end key |
toInclusive | true if the end key is in the returned map |
ClassCastException | |
---|---|
NullPointerException | if fromKey or toKey is null |
IllegalArgumentException |
Returns a view of the tail of the map whose keys are bigger than (or equal to, depends on inclusive argument) startKey.
fromKey | the start key |
---|---|
inclusive | true if the start key is in the returned map |
ClassCastException | |
---|---|
NullPointerException | if fromKey is null |
IllegalArgumentException |
Returns a sorted map over a range of this sorted map with all keys that
are greater than or equal to the specified startKey
. Changes to
the returned sorted map are reflected in this sorted map and vice versa.
Note: The returned map will not allow an insertion of a key outside the specified range.
fromKey | the low boundary of the range specified. |
---|
startKey
.ClassCastException | |
---|---|
NullPointerException | if fromKey is null |
IllegalArgumentException |
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 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.