lowerEntry, floorEntry, ceilingEntry,
lowerKey, floorKey, ceilingKey,
is new.
public interface NavigableMap<K,V>
A
SortedMap
extended with navigation methods returning the closest matches for given search targets. Methods
lowerEntry, floorEntry, ceilingEntry,
lowerEntry
,
floorEntry
,
ceilingEntry
,
and
higherEntry
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, floorKey, ceilingKey,
lowerKey
,
floorKey
,
ceilingKey
,
and
higherKey
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, headMap, and tailMap 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.
Implementations of entry-returning methods are expected to return Map.Entry pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional Entry.setValue method. Note however that it is possible to change mappings in the associated map using method put.
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 overriden to return NavigableSet.
This interface is a member of the
Java Collections Framework
.
Since:
1.6
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Nested Class Summary
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Nested classes/interfaces inherited from interface java.util.
Map
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Map.Entry
<
K
,
V
|
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Method Summary
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Map.Entry
<
K
,
V
|
ceilingEntry
(
K
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 key.
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K
|
ceilingKey
(
K
Returns the least key greater than or equal to the given key, or null if there is no such key.
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NavigableSet
<
K
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descendingKeySet
()
Returns a reverse order
NavigableSet
|
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NavigableMap
<
K
,
V
|
descendingMap
()
Returns a reverse order view of the mappings contained in this map.
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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.
|
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Map.Entry
<
K
,
V
|
floorEntry
(
K
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.
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|
K
|
floorKey
(
K
Returns the greatest key less than or equal to the given key, or null if there is no such key.
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SortedMap
<
K
,
V
|
headMap
(
K
Returns a view of the portion of this map whose keys are strictly less than
toKey
.
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NavigableMap
<
K
,
V
|
headMap
(
K
Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) toKey.
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Map.Entry
<
K
,
V
|
higherEntry
(
K
Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.
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K
|
higherKey
(
K
Returns the least key strictly greater than the given key, or null if there is no such key.
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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.
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Map.Entry
<
K
,
V
|
lowerEntry
(
K
Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.
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|
K
|
lowerKey
(
K
Returns the greatest key strictly less than the given key, or null if there is no such key.
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NavigableSet
<
K
|
navigableKeySet
()
Returns a
NavigableSet
|
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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.
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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.
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NavigableMap
<
K
,
V
|
subMap
(
K
fromKey, boolean fromInclusive,
K
Returns a view of the portion of this map whose keys range from fromKey to toKey.
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SortedMap
<
K
,
V
|
subMap
(
K
fromKey,
K
Returns a view of the portion of this map whose keys range from
fromKey
, inclusive, to
toKey
, exclusive.
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SortedMap
<
K
,
V
|
tailMap
(
K
Returns a view of the portion of this map whose keys are greater than or equal to
fromKey
.
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NavigableMap
<
K
,
V
|
tailMap
(
K
Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) fromKey.
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Methods inherited from interface java.util.
SortedMap
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comparator
,
entrySet
,
firstKey
,
keySet
,
lastKey
,
values
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Methods inherited from interface java.util.
Map
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clear
,
containsKey
,
containsValue
,
equals
,
get
,
hashCode
,
isEmpty
,
put
,
putAll
,
remove
,
size
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Method Detail
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lowerEntry
Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the greatest key less than key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
the greatest key less than key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the greatest key less than or equal to key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
the greatest key less than or equal to key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the least key greater than or equal to key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
the least key greater than or equal to key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the least key greater than key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if there is no such key.
Parameters:
key - the key
Returns:
the least key greater than key, or null if there is no such key
Throws:
ClassCastException
- if the specified key cannot be compared with the keys currently in the map
NullPointerException
- 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, or null if the map is empty.
Returns:
an entry with the least key, or null if this map is empty
lastEntry
Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
Returns:
an entry with the greatest key, or null if this map is empty
pollFirstEntry
Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.
Returns:
the removed first entry of this map, or null if this map is empty
pollLastEntry
Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
Returns:
the removed last entry of this map, or null if this map is empty
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 own remove operation), the results of the iteration are undefined.
The returned map has an ordering equivalent to
A
Collections.reverseOrder
(comparator())
NavigableMap
. The expression m.descendingMap().descendingMap() returns a view of m essentially equivalent to m.
Returns:
a reverse order view of this map
navigableKeySet
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. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. 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.
Returns:
a navigable set view of the keys in this map
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
.
Implementations of entry-returning methods are expected to return
Map.Entry
pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional
Entry.setValue
method. Note however that it is possible to change mappings in the associated map using method
put
.
This interface is a member of the
Java Collections Framework
.
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Map.Entry<K,V>lowerEntry(Kkey)
KlowerKey(Kkey)
Map.Entry<K,V>floorEntry(Kkey)
KfloorKey(Kkey)
Map.Entry<K,V>ceilingEntry(Kkey)
KceilingKey(Kkey)
Map.Entry<K,V>higherEntry(Kkey)
KhigherKey(Kkey)
Map.Entry<K,V>firstEntry()
Map.Entry<K,V>lastEntry()
Map.Entry<K,V>pollFirstEntry()
Map.Entry<K,V>pollLastEntry()
Set<K>descendingKeySet()
reverse order
NavigableSet
Iterator.remove, Set.remove, removeAll, retainAll,
reverse order navigable
set view of the keys
map
Set<Map.Entry<K,V>>descendingEntrySet()
NavigableMap<K,V>navigableSubMap(KfromKey,KtoKey)
The returned map will throw an
IllegalArgumentException
on an attempt to insert a key outside its range.
NavigableMap<K,V>navigableHeadMap(KtoKey)
The returned map will throw an
IllegalArgumentException
on an attempt to insert a key outside its range.
NavigableMap<K,V>navigableTailMap(KfromKey)
The returned map will throw an
IllegalArgumentException
on an attempt to insert a key outside its range.
headMap
Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is true) toKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
Parameters:
toKey - high endpoint of the keys in the returned map
inclusive - 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
- if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement
Comparable
). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
NullPointerException
- if toKey is null and this map does not permit null keys
IllegalArgumentException
- if this map itself has a restricted range, and toKey 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, if inclusive is true) fromKey. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an IllegalArgumentException on an attempt to insert a key outside its range.
Parameters:
fromKey - low endpoint of the keys in the returned map
inclusive - 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
- if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement
Comparable
). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
NullPointerException
- if fromKey is null and this map does not permit null keys
IllegalArgumentException
- if this map itself has a restricted range, and fromKey lies outside the bounds of the range
subMap
Returns a view of the portion of this map whose keys range from
fromKey
, inclusive, to
toKey
, exclusive. (If
fromKey
and
toKey
are equal, the returned map is empty.) The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an
IllegalArgumentException
on an attempt to insert a key outside its range.
Equivalent to subMap(fromKey, true, toKey, false).
Specified by:
subMap
in interface
SortedMap
<
K
,
V
>
Parameters:
fromKey - low endpoint (inclusive) of the keys in the returned map
toKey - 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, 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). Implementations may, but are not required to, throw this exception if
fromKey
or
toKey
cannot be compared to keys currently in the map.
NullPointerException
- if
fromKey
or
toKey
is null and this map does not permit null keys
IllegalArgumentException
- if
fromKey
is greater than
toKey
; or if this map itself has a restricted range, and
fromKey
or
toKey
lies outside the bounds of the range
headMap
Returns a view of the portion of this map whose keys are strictly less than
toKey
. The returned map is backed by this map, so changes in the returned map are reflected in this map, and vice-versa. The returned map supports all optional map operations that this map supports.
The returned map will throw an
IllegalArgumentException
on an attempt to insert a key outside its range.
Equivalent to headMap(toKey, false).
Specified by:
headMap
in interface
SortedMap
<
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
- if
toKey
is not compatible with this map's comparator (or, if the map has no comparator, if
toKey
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
toKey
cannot be compared to keys currently in the map.
NullPointerException
- if
toKey
is null and this map does not permit null keys
IllegalArgumentException
- if this map itself has a restricted range, and
toKey
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
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).
Specified by:
tailMap
in interface
SortedMap
<
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
- if
fromKey
is not compatible with this map's comparator (or, if the map has no comparator, if
fromKey
does not implement
Comparable
). Implementations may, but are not required to, throw this exception if
fromKey
cannot be compared to keys currently in the map.
NullPointerException
- if
fromKey
is null and this map does not permit null keys
IllegalArgumentException
- if this map itself has a restricted range, and
fromKey
lies outside the bounds of the range