public
interface
NavigableMap
implements
SortedMap<K, V>
java.util.NavigableMap<K, V> |
Known Indirect Subclasses
|
A 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
.
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,
keySet()
can be overridden to return NavigableSet
.
Public methods | |
---|---|
abstract
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 |
abstract
K
|
ceilingKey(K key)
Returns the least key greater than or equal to the given key,
or |
abstract
NavigableSet<K>
|
descendingKeySet()
Returns a reverse order |
abstract
NavigableMap<K, V>
|
descendingMap()
Returns a reverse order view of the mappings contained in this map. |
abstract
Entry<K, V>
|
firstEntry()
Returns a key-value mapping associated with the least
key in this map, or |
abstract
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 |
abstract
K
|
floorKey(K key)
Returns the greatest key less than or equal to the given key,
or |
abstract
SortedMap<K, V>
|
headMap(K toKey)
Returns a view of the portion of this map whose keys are
strictly less than Equivalent to |
abstract
NavigableMap<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 |
abstract
Entry<K, V>
|
higherEntry(K key)
Returns a key-value mapping associated with the least key
strictly greater than the given key, or |
abstract
K
|
higherKey(K key)
Returns the least key strictly greater than the given key, or
|
abstract
Entry<K, V>
|
lastEntry()
Returns a key-value mapping associated with the greatest
key in this map, or |
abstract
Entry<K, V>
|
lowerEntry(K key)
Returns a key-value mapping associated with the greatest key
strictly less than the given key, or |
abstract
K
|
lowerKey(K key)
Returns the greatest key strictly less than the given key, or
|
abstract
NavigableSet<K>
|
navigableKeySet()
Returns a |
abstract
Entry<K, V>
|
pollFirstEntry()
Removes and returns a key-value mapping associated with
the least key in this map, or |
abstract
Entry<K, V>
|
pollLastEntry()
Removes and returns a key-value mapping associated with
the greatest key in this map, or |
abstract
SortedMap<K, V>
|
subMap(K fromKey, K toKey)
Returns a view of the portion of this map whose keys range from
Equivalent to |
abstract
NavigableMap<K, V>
|
subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)
Returns a view of the portion of this map whose keys range from
|
abstract
NavigableMap<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 |
abstract
SortedMap<K, V>
|
tailMap(K fromKey)
Returns a view of the portion of this map whose keys are
greater than or equal to Equivalent to |
Inherited methods | |
---|---|
From
interface
java.util.SortedMap
| |
From
interface
java.util.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 key.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
Entry<K, V> |
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 |
K ceilingKey (K key)
Returns the least key greater than or equal to the given key,
or null
if there is no such key.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
K |
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 |
NavigableSet<K> descendingKeySet ()
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. 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 | |
---|---|
NavigableSet<K> |
a reverse order navigable set view of the keys in this map |
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 own remove
operation), the results of the iteration are undefined.
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 | |
---|---|
NavigableMap<K, V> |
a reverse order view of this 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.
Returns | |
---|---|
Entry<K, V> |
an entry with the least key,
or null if this map is empty
|
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.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
Entry<K, V> |
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 |
K floorKey (K key)
Returns the greatest key less than or equal to the given key,
or null
if there is no such key.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
K |
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 |
SortedMap<K, V> headMap (K toKey)
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)
.
Parameters | |
---|---|
toKey |
K :
high endpoint (exclusive) of the keys in the returned map |
Returns | |
---|---|
SortedMap<K, V> |
a view of the portion of this map whose keys are strictly
less than toKey |
Throws | |
---|---|
ClassCastException |
|
NullPointerException |
|
IllegalArgumentException |
NavigableMap<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
. 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 |
K :
high endpoint of the keys in the returned map |
inclusive |
boolean :
true if the high endpoint
is to be included in the returned view |
Returns | |
---|---|
NavigableMap<K, V> |
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
|
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.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
Entry<K, V> |
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 |
K higherKey (K key)
Returns the least key strictly greater than the given key, or
null
if there is no such key.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
K |
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 |
Entry<K, V> lastEntry ()
Returns a key-value mapping associated with the greatest
key in this map, or null
if the map is empty.
Returns | |
---|---|
Entry<K, V> |
an entry with the greatest key,
or null if this map is empty
|
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.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
Entry<K, V> |
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 |
K lowerKey (K key)
Returns the greatest key strictly less than the given key, or
null
if there is no such key.
Parameters | |
---|---|
key |
K :
the key |
Returns | |
---|---|
K |
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 |
NavigableSet<K> 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 | |
---|---|
NavigableSet<K> |
a navigable set view of the keys in this 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.
Returns | |
---|---|
Entry<K, V> |
the removed first entry of this map,
or null if this map is empty
|
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.
Returns | |
---|---|
Entry<K, V> |
the removed last entry of this map,
or null if this map is empty
|
SortedMap<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 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)
.
Parameters | |
---|---|
fromKey |
K :
low endpoint (inclusive) of the keys in the returned map |
toKey |
K :
high endpoint (exclusive) of the keys in the returned map |
Returns | |
---|---|
SortedMap<K, V> |
a view of the portion of this map whose keys range from
fromKey , inclusive, to toKey , exclusive |
Throws | |
---|---|
ClassCastException |
|
NullPointerException |
|
IllegalArgumentException |
NavigableMap<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
. 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.
Parameters | |
---|---|
fromKey |
K :
low endpoint of the keys in the returned map |
fromInclusive |
boolean :
true if the low endpoint
is to be included in the returned view |
toKey |
K :
high endpoint of the keys in the returned map |
toInclusive |
boolean :
true if the high endpoint
is to be included in the returned view |
Returns | |
---|---|
NavigableMap<K, V> |
a view of the portion of this map whose keys range from
fromKey to toKey |
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
|
NavigableMap<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
. 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 |
K :
low endpoint of the keys in the returned map |
inclusive |
boolean :
true if the low endpoint
is to be included in the returned view |
Returns | |
---|---|
NavigableMap<K, V> |
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
|
SortedMap<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 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)
.
Parameters | |
---|---|
fromKey |
K :
low endpoint (inclusive) of the keys in the returned map |
Returns | |
---|---|
SortedMap<K, V> |
a view of the portion of this map whose keys are greater
than or equal to fromKey |
Throws | |
---|---|
ClassCastException |
|
NullPointerException |
|
IllegalArgumentException |