Interface NavigableMap<K,V>
- Type Parameters:
K
- the type of keys maintained by this mapV
- the type of mapped values
- All Superinterfaces:
Map<K,
,V> SequencedMap<K,
,V> SortedMap<K,
V>
- All Known Subinterfaces:
ConcurrentNavigableMap<K,
V>
- All Known Implementing Classes:
ConcurrentSkipListMap
,TreeMap
SortedMap
extended with navigation methods returning the
closest matches for given search targets. Methods
lowerEntry(K)
, floorEntry(K)
, ceilingEntry(K)
,
and higherEntry(K)
return Map.Entry
objects
associated with keys respectively less than, less than or equal,
greater than or equal, and greater than a given key, returning
null
if there is no such key. Similarly, methods
lowerKey(K)
, floorKey(K)
, ceilingKey(K)
, and
higherKey(K)
return only the associated keys. All of these
methods are designed for locating, not traversing entries.
A NavigableMap
may be accessed and traversed in either
ascending or descending key order. The descendingMap()
method returns a view of the map with the senses of all relational
and directional methods inverted. The performance of ascending
operations and views is likely to be faster than that of descending
ones. Methods
subMap(K, boolean, K, boolean)
,
headMap(K, boolean)
, and
tailMap(K, boolean)
differ from the like-named SortedMap
methods in accepting
additional arguments describing whether lower and upper bounds are
inclusive versus exclusive. Submaps of any NavigableMap
must implement the NavigableMap
interface.
This interface additionally defines methods firstEntry()
,
pollFirstEntry()
, lastEntry()
, and
pollLastEntry()
that return and/or remove the least and
greatest mappings, if any exist, else returning null
.
The methods
ceilingEntry(K)
,
firstEntry()
,
floorEntry(K)
,
higherEntry(K)
,
lastEntry()
,
lowerEntry(K)
,
pollFirstEntry()
, and
pollLastEntry()
return Map.Entry
instances that represent snapshots of mappings as
of the time of the call. They do not support mutation of the
underlying map via the optional setValue
method.
Methods
subMap(K, K)
,
headMap(K)
, and
tailMap(K)
are specified to return SortedMap
to allow existing
implementations of SortedMap
to be compatibly retrofitted to
implement NavigableMap
, but extensions and implementations
of this interface are encouraged to override these methods to return
NavigableMap
. Similarly,
SortedMap.keySet()
can be overridden to return NavigableSet
.
This interface is a member of the Java Collections Framework.
- Since:
- 1.6
-
Nested Class Summary
-
Method Summary
Modifier and TypeMethodDescriptionceilingEntry
(K key) Returns a key-value mapping associated with the least key greater than or equal to the given key, ornull
if there is no such key.ceilingKey
(K key) Returns the least key greater than or equal to the given key, ornull
if there is no such key.Returns a reverse orderNavigableSet
view of the keys contained in this map.Returns a reverse order view of the mappings contained in this map.Returns a key-value mapping associated with the least key in this map, ornull
if the map is empty.floorEntry
(K key) Returns a key-value mapping associated with the greatest key less than or equal to the given key, ornull
if there is no such key.Returns the greatest key less than or equal to the given key, ornull
if there is no such key.Returns a view of the portion of this map whose keys are strictly less thantoKey
.Returns a view of the portion of this map whose keys are less than (or equal to, ifinclusive
is true)toKey
.higherEntry
(K key) Returns a key-value mapping associated with the least key strictly greater than the given key, ornull
if there is no such key.Returns the least key strictly greater than the given key, ornull
if there is no such key.Returns a key-value mapping associated with the greatest key in this map, ornull
if the map is empty.lowerEntry
(K key) Returns a key-value mapping associated with the greatest key strictly less than the given key, ornull
if there is no such key.Returns the greatest key strictly less than the given key, ornull
if there is no such key.Returns aNavigableSet
view of the keys contained in this map.Removes and returns a key-value mapping associated with the least key in this map, ornull
if the map is empty (optional operation).Removes and returns a key-value mapping associated with the greatest key in this map, ornull
if the map is empty (optional operation).default NavigableMap
<K, V> reversed()
Returns a reverse-ordered view of this map.Returns a view of the portion of this map whose keys range fromfromKey
totoKey
.Returns a view of the portion of this map whose keys range fromfromKey
, inclusive, totoKey
, exclusive.Returns a view of the portion of this map whose keys are greater than or equal tofromKey
.Returns a view of the portion of this map whose keys are greater than (or equal to, ifinclusive
is true)fromKey
.Methods inherited from interface java.util.Map
clear, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, equals, forEach, get, getOrDefault, hashCode, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, replaceAll, size
Methods inherited from interface java.util.SequencedMap
sequencedEntrySet, sequencedKeySet, sequencedValues
-
Method Details
-
lowerEntry
Returns a key-value mapping associated with the greatest key strictly less than the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- an entry with the greatest key less than
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
lowerKey
Returns the greatest key strictly less than the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- the greatest key less than
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
floorEntry
Returns a key-value mapping associated with the greatest key less than or equal to the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- an entry with the greatest key less than or equal to
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
floorKey
Returns the greatest key less than or equal to the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- the greatest key less than or equal to
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
ceilingEntry
Returns a key-value mapping associated with the least key greater than or equal to the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- an entry with the least key greater than or equal to
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
ceilingKey
Returns the least key greater than or equal to the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- the least key greater than or equal to
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
higherEntry
Returns a key-value mapping associated with the least key strictly greater than the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- an entry with the least key greater than
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
higherKey
Returns the least key strictly greater than the given key, ornull
if there is no such key.- Parameters:
key
- the key- Returns:
- the least key greater than
key
, ornull
if there is no such key - Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the mapNullPointerException
- if the specified key is null and this map does not permit null keys
-
firstEntry
Returns a key-value mapping associated with the least key in this map, ornull
if the map is empty.- Specified by:
firstEntry
in interfaceSequencedMap<K,
V> - Returns:
- an entry with the least key,
or
null
if this map is empty
-
lastEntry
-
pollFirstEntry
Removes and returns a key-value mapping associated with the least key in this map, ornull
if the map is empty (optional operation).- Specified by:
pollFirstEntry
in interfaceSequencedMap<K,
V> - Returns:
- the removed first entry of this map,
or
null
if this map is empty - Throws:
UnsupportedOperationException
- if thepollFirstEntry
operation is not supported by this map
-
pollLastEntry
Removes and returns a key-value mapping associated with the greatest key in this map, ornull
if the map is empty (optional operation).- Specified by:
pollLastEntry
in interfaceSequencedMap<K,
V> - Returns:
- the removed last entry of this map,
or
null
if this map is empty - Throws:
UnsupportedOperationException
- if thepollLastEntry
operation is not supported by this map
-
descendingMap
NavigableMap<K,V> descendingMap()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. If either map is modified while an iteration over a collection view of either map is in progress (except through the iterator's ownremove
operation), the results of the iteration are undefined.The returned map has an ordering equivalent to
Collections.reverseOrder
(comparator())
. The expressionm.descendingMap().descendingMap()
returns a view ofm
essentially equivalent tom
.- Returns:
- a reverse order view of this map
-
descendingKeySet
NavigableSet<K> descendingKeySet()Returns a reverse orderNavigableSet
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. If the map is modified while an iteration over the set is in progress (except through the iterator's ownremove
operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove
,Set.remove
,removeAll
,retainAll
, andclear
operations. It does not support theadd
oraddAll
operations.- Returns:
- a reverse order navigable set view of the keys in this map
-
subMap
Returns a view of the portion of this map whose keys range fromfromKey
totoKey
. IffromKey
andtoKey
are equal, the returned map is empty unlessfromInclusive
andtoInclusive
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.- Parameters:
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 view- Returns:
- a view of the portion of this map whose keys range from
fromKey
totoKey
- Throws:
ClassCastException
- iffromKey
andtoKey
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 iffromKey
ortoKey
cannot be compared to keys currently in the map.NullPointerException
- iffromKey
ortoKey
is null and this map does not permit null keysIllegalArgumentException
- iffromKey
is greater thantoKey
; or if this map itself has a restricted range, andfromKey
ortoKey
lies outside the bounds of the range
-
headMap
Returns a view of the portion of this map whose keys are less than (or equal to, ifinclusive
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.- Parameters:
toKey
- high endpoint of the keys in the returned mapinclusive
-true
if the high endpoint is to be included in the returned view- Returns:
- a view of the portion of this map whose keys are less than
(or equal to, if
inclusive
is true)toKey
- Throws:
ClassCastException
- iftoKey
is not compatible with this map's comparator (or, if the map has no comparator, iftoKey
does not implementComparable
). Implementations may, but are not required to, throw this exception iftoKey
cannot be compared to keys currently in the map.NullPointerException
- iftoKey
is null and this map does not permit null keysIllegalArgumentException
- if this map itself has a restricted range, andtoKey
lies outside the bounds of the range
-
tailMap
Returns a view of the portion of this map whose keys are greater than (or equal to, ifinclusive
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.- Parameters:
fromKey
- low endpoint of the keys in the returned mapinclusive
-true
if the low endpoint is to be included in the returned view- Returns:
- a view of the portion of this map whose keys are greater than
(or equal to, if
inclusive
is true)fromKey
- Throws:
ClassCastException
- iffromKey
is not compatible with this map's comparator (or, if the map has no comparator, iffromKey
does not implementComparable
). Implementations may, but are not required to, throw this exception iffromKey
cannot be compared to keys currently in the map.NullPointerException
- iffromKey
is null and this map does not permit null keysIllegalArgumentException
- if this map itself has a restricted range, andfromKey
lies outside the bounds of the range
-
subMap
Returns a view of the portion of this map whose keys range fromfromKey
, inclusive, totoKey
, exclusive. (IffromKey
andtoKey
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)
.- Specified by:
subMap
in interfaceSortedMap<K,
V> - Parameters:
fromKey
- low endpoint (inclusive) of the keys in the returned maptoKey
- high endpoint (exclusive) of the keys in the returned map- Returns:
- a view of the portion of this map whose keys range from
fromKey
, inclusive, totoKey
, exclusive - Throws:
ClassCastException
- iffromKey
andtoKey
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 iffromKey
ortoKey
cannot be compared to keys currently in the map.NullPointerException
- iffromKey
ortoKey
is null and this map does not permit null keysIllegalArgumentException
- iffromKey
is greater thantoKey
; or if this map itself has a restricted range, andfromKey
ortoKey
lies outside the bounds of the range
-
headMap
Returns a view of the portion of this map whose keys are strictly less thantoKey
. 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)
.- Specified by:
headMap
in interfaceSortedMap<K,
V> - Parameters:
toKey
- high endpoint (exclusive) of the keys in the returned map- Returns:
- a view of the portion of this map whose keys are strictly
less than
toKey
- Throws:
ClassCastException
- iftoKey
is not compatible with this map's comparator (or, if the map has no comparator, iftoKey
does not implementComparable
). Implementations may, but are not required to, throw this exception iftoKey
cannot be compared to keys currently in the map.NullPointerException
- iftoKey
is null and this map does not permit null keysIllegalArgumentException
- if this map itself has a restricted range, andtoKey
lies outside the bounds of the range
-
tailMap
Returns a view of the portion of this map whose keys are greater than or equal tofromKey
. 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)
.- Specified by:
tailMap
in interfaceSortedMap<K,
V> - Parameters:
fromKey
- low endpoint (inclusive) of the keys in the returned map- Returns:
- a view of the portion of this map whose keys are greater
than or equal to
fromKey
- Throws:
ClassCastException
- iffromKey
is not compatible with this map's comparator (or, if the map has no comparator, iffromKey
does not implementComparable
). Implementations may, but are not required to, throw this exception iffromKey
cannot be compared to keys currently in the map.NullPointerException
- iffromKey
is null and this map does not permit null keysIllegalArgumentException
- if this map itself has a restricted range, andfromKey
lies outside the bounds of the range
-
reversed
Returns a reverse-ordered view of this map. The encounter order of mappings in the returned view is the inverse of the encounter order of mappings in this map. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the implementation permits modifications to this view, the modifications "write through" to the underlying map. Changes to the underlying map might or might not be visible in this reversed view, depending upon the implementation.This method is equivalent to
descendingMap
.
-