K
- the type of keys maintained by this mapV
- the type of mapped valuespublic class ConcurrentSkipListMap<K,V> extends AbstractMap<K,V> implements ConcurrentNavigableMap<K,V>, Cloneable, Serializable
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, 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.
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
Constructor and Description |
---|
ConcurrentSkipListMap()
Constructs a new, empty map, sorted according to the
natural ordering 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 natural ordering 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.
|
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 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 natural ordering of its keys. |
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. |
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. |
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. |
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.
|
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. |
hashCode, putAll, toString
public ConcurrentSkipListMap()
public ConcurrentSkipListMap(Comparator<? super K> comparator)
comparator
- the comparator that will be used to order this map.
If null, the natural
ordering of the keys will be used.public ConcurrentSkipListMap(Map<? extends K,? extends V> m)
m
- the map whose mappings are to be placed in this mapClassCastException
- if the keys in m are not
Comparable
, or are not mutually comparableNullPointerException
- if the specified map or any of its keys
or values are nullpublic ConcurrentSkipListMap(SortedMap<K,? extends V> m)
m
- the sorted map whose mappings are to be placed in this
map, and whose comparator is to be used to sort this mapNullPointerException
- if the specified sorted map or any of
its keys or values are nullpublic ConcurrentSkipListMap<K,V> clone()
clone
in class AbstractMap<K,V>
Cloneable
public boolean containsKey(Object key)
containsKey
in interface Map<K,V>
containsKey
in class AbstractMap<K,V>
key
- key whose presence in this map is to be testedClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic V get(Object key)
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.)
get
in interface Map<K,V>
get
in class AbstractMap<K,V>
key
- the key whose associated value is to be returnednull
if this map contains no mapping for the keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic V put(K key, V value)
put
in interface Map<K,V>
put
in class AbstractMap<K,V>
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key or value is nullpublic V remove(Object key)
remove
in interface Map<K,V>
remove
in class AbstractMap<K,V>
key
- key for which mapping should be removedClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic boolean containsValue(Object value)
containsValue
in interface Map<K,V>
containsValue
in class AbstractMap<K,V>
value
- value whose presence in this map is to be testedNullPointerException
- if the specified value is nullpublic int size()
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.
public boolean isEmpty()
public void clear()
public NavigableSet<K> keySet()
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
.
public NavigableSet<K> navigableKeySet()
ConcurrentNavigableMap
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.
navigableKeySet
in interface ConcurrentNavigableMap<K,V>
navigableKeySet
in interface NavigableMap<K,V>
public Collection<V> values()
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.
public Set<Map.Entry<K,V>> entrySet()
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.
public ConcurrentNavigableMap<K,V> descendingMap()
ConcurrentNavigableMap
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
.
descendingMap
in interface ConcurrentNavigableMap<K,V>
descendingMap
in interface NavigableMap<K,V>
public NavigableSet<K> descendingKeySet()
ConcurrentNavigableMap
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.
descendingKeySet
in interface ConcurrentNavigableMap<K,V>
descendingKeySet
in interface NavigableMap<K,V>
public boolean equals(Object o)
equals
in interface Map<K,V>
equals
in class AbstractMap<K,V>
o
- object to be compared for equality with this mapObject.hashCode()
,
HashMap
public V putIfAbsent(K key, V value)
if (!map.containsKey(key)) return map.put(key, value); else return map.get(key);except that the action is performed atomically.
putIfAbsent
in interface ConcurrentMap<K,V>
key
- key with which the specified value is to be associatedvalue
- value to be associated with the specified keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key or value is nullpublic boolean remove(Object key, Object value)
if (map.containsKey(key) && map.get(key).equals(value)) { map.remove(key); return true; } else return false;except that the action is performed atomically.
remove
in interface ConcurrentMap<K,V>
key
- key with which the specified value is associatedvalue
- value expected to be associated with the specified keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic boolean replace(K key, V oldValue, V newValue)
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.
replace
in interface ConcurrentMap<K,V>
key
- key with which the specified value is associatedoldValue
- value expected to be associated with the specified keynewValue
- value to be associated with the specified keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if any of the arguments are nullpublic V replace(K key, V value)
if (map.containsKey(key)) { return map.put(key, value); } else return null;except that the action is performed atomically.
replace
in interface ConcurrentMap<K,V>
key
- key with which the specified value is associatedvalue
- value to be associated with the specified keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key or value is nullpublic Comparator<? super K> comparator()
SortedMap
null
if this map uses the natural ordering of its keys.comparator
in interface SortedMap<K,V>
null
if this map uses the natural ordering
of its keyspublic K firstKey()
SortedMap
firstKey
in interface SortedMap<K,V>
NoSuchElementException
- if this map is emptypublic K lastKey()
SortedMap
lastKey
in interface SortedMap<K,V>
NoSuchElementException
- if this map is emptypublic ConcurrentNavigableMap<K,V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)
NavigableMap
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.
subMap
in interface ConcurrentNavigableMap<K,V>
subMap
in interface NavigableMap<K,V>
fromKey
- low endpoint of the keys in the returned mapfromInclusive
- true
if the low endpoint
is to be included in the returned viewtoKey
- high endpoint of the keys in the returned maptoInclusive
- true
if the high endpoint
is to be included in the returned viewfromKey
to toKey
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 nullIllegalArgumentException
- 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 rangepublic ConcurrentNavigableMap<K,V> headMap(K toKey, boolean inclusive)
NavigableMap
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.
headMap
in interface ConcurrentNavigableMap<K,V>
headMap
in interface NavigableMap<K,V>
toKey
- high endpoint of the keys in the returned mapinclusive
- true
if the high endpoint
is to be included in the returned viewinclusive
is true) toKey
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 nullIllegalArgumentException
- if this map itself has a
restricted range, and toKey
lies outside the
bounds of the rangepublic ConcurrentNavigableMap<K,V> tailMap(K fromKey, boolean inclusive)
NavigableMap
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.
tailMap
in interface ConcurrentNavigableMap<K,V>
tailMap
in interface NavigableMap<K,V>
fromKey
- low endpoint of the keys in the returned mapinclusive
- true
if the low endpoint
is to be included in the returned viewinclusive
is true) fromKey
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 nullIllegalArgumentException
- if this map itself has a
restricted range, and fromKey
lies outside the
bounds of the rangepublic ConcurrentNavigableMap<K,V> subMap(K fromKey, K toKey)
NavigableMap
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)
.
subMap
in interface ConcurrentNavigableMap<K,V>
subMap
in interface NavigableMap<K,V>
subMap
in interface SortedMap<K,V>
fromKey
- low endpoint (inclusive) of the keys in the returned maptoKey
- high endpoint (exclusive) of the keys in the returned mapfromKey
, inclusive, to toKey
, exclusiveClassCastException
- 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 nullIllegalArgumentException
- 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 rangepublic ConcurrentNavigableMap<K,V> headMap(K toKey)
NavigableMap
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)
.
headMap
in interface ConcurrentNavigableMap<K,V>
headMap
in interface NavigableMap<K,V>
headMap
in interface SortedMap<K,V>
toKey
- high endpoint (exclusive) of the keys in the returned maptoKey
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 nullIllegalArgumentException
- if this map itself has a
restricted range, and toKey
lies outside the
bounds of the rangepublic ConcurrentNavigableMap<K,V> tailMap(K fromKey)
NavigableMap
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)
.
tailMap
in interface ConcurrentNavigableMap<K,V>
tailMap
in interface NavigableMap<K,V>
tailMap
in interface SortedMap<K,V>
fromKey
- low endpoint (inclusive) of the keys in the returned mapfromKey
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 nullIllegalArgumentException
- if this map itself has a
restricted range, and fromKey
lies outside the
bounds of the rangepublic Map.Entry<K,V> lowerEntry(K key)
lowerEntry
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic K lowerKey(K key)
NavigableMap
null
if there is no such key.lowerKey
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic Map.Entry<K,V> floorEntry(K key)
floorEntry
in interface NavigableMap<K,V>
key
- the keykey
, or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic K floorKey(K key)
NavigableMap
null
if there is no such key.floorKey
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic Map.Entry<K,V> ceilingEntry(K key)
ceilingEntry
in interface NavigableMap<K,V>
key
- the keykey
, or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic K ceilingKey(K key)
NavigableMap
null
if there is no such key.ceilingKey
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic Map.Entry<K,V> higherEntry(K key)
higherEntry
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic K higherKey(K key)
NavigableMap
null
if there is no such key.higherKey
in interface NavigableMap<K,V>
key
- the keykey
,
or null
if there is no such keyClassCastException
- if the specified key cannot be compared
with the keys currently in the mapNullPointerException
- if the specified key is nullpublic Map.Entry<K,V> firstEntry()
firstEntry
in interface NavigableMap<K,V>
null
if this map is emptypublic Map.Entry<K,V> lastEntry()
lastEntry
in interface NavigableMap<K,V>
null
if this map is emptypublic Map.Entry<K,V> pollFirstEntry()
pollFirstEntry
in interface NavigableMap<K,V>
null
if this map is emptypublic Map.Entry<K,V> pollLastEntry()
pollLastEntry
in interface NavigableMap<K,V>
null
if this map is empty Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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