edu.emory.mathcs.backport.java.util
public interface NavigableMap extends SortedMap
A {@code NavigableMap} may be accessed and traversed in either ascending or descending key order. The {@code 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 {@code subMap}, {@code headMap}, and {@code tailMap} differ from the like-named {@code SortedMap} methods in accepting additional arguments describing whether lower and upper bounds are inclusive versus exclusive. Submaps of any {@code NavigableMap} must implement the {@code NavigableMap} interface.
This interface additionally defines methods {@code firstEntry}, {@code pollFirstEntry}, {@code lastEntry}, and {@code pollLastEntry} that return and/or remove the least and greatest mappings, if any exist, else returning {@code null}.
Implementations of entry-returning methods are expected to return {@code Map.Entry} pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional {@code Entry.setValue} method. Note however that it is possible to change mappings in the associated map using method {@code put}.
Methods
subMap(K, K)
,
headMap(K)
, and
tailMap(K)
are specified to return {@code SortedMap} to allow existing
implementations of {@code SortedMap} to be compatibly retrofitted to
implement {@code NavigableMap}, but extensions and implementations
of this interface are encouraged to override these methods to return
{@code NavigableMap}. Similarly,
NavigableMap can be overriden to return {@code NavigableSet}.
This interface is a member of the Java Collections Framework.
Since: 1.6
Method Summary | |
---|---|
Entry | ceilingEntry(Object key)
Returns a key-value mapping associated with the least key
greater than or equal to the given key, or {@code null} if
there is no such key.
|
Object | ceilingKey(Object key)
Returns the least key greater than or equal to the given key,
or {@code null} if there is no such key.
|
NavigableSet | descendingKeySet()
Returns a reverse order NavigableSet view of the keys contained in this map.
|
NavigableMap | descendingMap()
Returns a reverse order view of the mappings contained in this map.
|
Entry | firstEntry()
Returns a key-value mapping associated with the least
key in this map, or {@code null} if the map is empty.
|
Entry | floorEntry(Object key)
Returns a key-value mapping associated with the greatest key
less than or equal to the given key, or {@code null} if there
is no such key.
|
Object | floorKey(Object key)
Returns the greatest key less than or equal to the given key,
or {@code null} if there is no such key.
|
NavigableMap | headMap(Object toKey, boolean inclusive)
Returns a view of the portion of this map whose keys are less than (or
equal to, if {@code inclusive} is true) {@code toKey}. |
SortedMap | headMap(Object toKey)
{@inheritDoc }
Equivalent to {@code headMap(toKey, false)}. |
Entry | higherEntry(Object key)
Returns a key-value mapping associated with the least key
strictly greater than the given key, or {@code null} if there
is no such key.
|
Object | higherKey(Object key)
Returns the least key strictly greater than the given key, or
{@code null} if there is no such key.
|
Entry | lastEntry()
Returns a key-value mapping associated with the greatest
key in this map, or {@code null} if the map is empty.
|
Entry | lowerEntry(Object key)
Returns a key-value mapping associated with the greatest key
strictly less than the given key, or {@code null} if there is
no such key.
|
Object | lowerKey(Object key)
Returns the greatest key strictly less than the given key, or
{@code null} if there is no such key.
|
NavigableSet | navigableKeySet()
Returns a NavigableSet view of the keys contained in this map.
|
Entry | pollFirstEntry()
Removes and returns a key-value mapping associated with
the least key in this map, or {@code null} if the map is empty.
|
Entry | pollLastEntry()
Removes and returns a key-value mapping associated with
the greatest key in this map, or {@code null} if the map is empty.
|
NavigableMap | subMap(Object fromKey, boolean fromInclusive, Object toKey, boolean toInclusive)
Returns a view of the portion of this map whose keys range from
{@code fromKey} to {@code toKey}. |
SortedMap | subMap(Object fromKey, Object toKey)
{@inheritDoc }
Equivalent to {@code subMap(fromKey, true, toKey, false)}. |
NavigableMap | tailMap(Object fromKey, boolean inclusive)
Returns a view of the portion of this map whose keys are greater than (or
equal to, if {@code inclusive} is true) {@code fromKey}. |
SortedMap | tailMap(Object fromKey)
{@inheritDoc }
Equivalent to {@code tailMap(fromKey, true)}. |
Parameters: key the key
Returns: an entry with the least key greater than or equal to {@code key}, or {@code 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
Parameters: key the key
Returns: the least key greater than or equal to {@code key}, or {@code 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
Returns: a reverse order navigable set view of the keys in this map
The returned map has an ordering equivalent to
Collections.reverseOrder
(comparator()).
The expression {@code m.descendingMap().descendingMap()} returns a
view of {@code m} essentially equivalent to {@code m}.
Returns: a reverse order view of this map
Returns: an entry with the least key, or {@code null} if this map is empty
Parameters: key the key
Returns: an entry with the greatest key less than or equal to {@code key}, or {@code 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
Parameters: key the key
Returns: the greatest key less than or equal to {@code key}, or {@code 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
The returned map will throw an {@code IllegalArgumentException} on an attempt to insert a key outside its range.
Parameters: toKey high endpoint of the keys in the returned map inclusive {@code 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 {@code inclusive} is true) {@code toKey}
Throws: ClassCastException if {@code toKey} is not compatible with this map's comparator (or, if the map has no comparator, if {@code toKey} does not implement java.lang.Comparable). Implementations may, but are not required to, throw this exception if {@code toKey} cannot be compared to keys currently in the map. NullPointerException if {@code toKey} is null and this map does not permit null keys IllegalArgumentException if this map itself has a restricted range, and {@code toKey} lies outside the bounds of the range
Equivalent to {@code headMap(toKey, false)}.
Throws: ClassCastException {@inheritDoc } NullPointerException {@inheritDoc } IllegalArgumentException {@inheritDoc }
Parameters: key the key
Returns: an entry with the least key greater than {@code key}, or {@code 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
Parameters: key the key
Returns: the least key greater than {@code key}, or {@code 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
Returns: an entry with the greatest key, or {@code null} if this map is empty
Parameters: key the key
Returns: an entry with the greatest key less than {@code key}, or {@code 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
Parameters: key the key
Returns: the greatest key less than {@code key}, or {@code 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
Returns: a navigable set view of the keys in this map
Returns: the removed first entry of this map, or {@code null} if this map is empty
Returns: the removed last entry of this map, or {@code null} if this map is empty
The returned map will throw an {@code 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 map fromInclusive {@code true} if the low endpoint is to be included in the returned view toKey high endpoint of the keys in the returned map toInclusive {@code 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 {@code fromKey} to {@code toKey}
Throws: ClassCastException if {@code fromKey} and {@code 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 {@code fromKey} or {@code toKey} cannot be compared to keys currently in the map. NullPointerException if {@code fromKey} or {@code toKey} is null and this map does not permit null keys IllegalArgumentException if {@code fromKey} is greater than {@code toKey}; or if this map itself has a restricted range, and {@code fromKey} or {@code toKey} lies outside the bounds of the range
Equivalent to {@code subMap(fromKey, true, toKey, false)}.
Throws: ClassCastException {@inheritDoc } NullPointerException {@inheritDoc } IllegalArgumentException {@inheritDoc }
The returned map will throw an {@code IllegalArgumentException} on an attempt to insert a key outside its range.
Parameters: fromKey low endpoint of the keys in the returned map inclusive {@code 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 {@code inclusive} is true) {@code fromKey}
Throws: ClassCastException if {@code fromKey} is not compatible with this map's comparator (or, if the map has no comparator, if {@code fromKey} does not implement java.lang.Comparable). Implementations may, but are not required to, throw this exception if {@code fromKey} cannot be compared to keys currently in the map. NullPointerException if {@code fromKey} is null and this map does not permit null keys IllegalArgumentException if this map itself has a restricted range, and {@code fromKey} lies outside the bounds of the range
Equivalent to {@code tailMap(fromKey, true)}.
Throws: ClassCastException {@inheritDoc } NullPointerException {@inheritDoc } IllegalArgumentException {@inheritDoc }