edu.emory.mathcs.backport.java.util
Interface NavigableMap

All Superinterfaces:

java.util.Map, java.util.SortedMap

All Known Subinterfaces:

ConcurrentNavigableMap

All Known Implementing Classes:

ConcurrentSkipListMap, TreeMap

public interface NavigableMap

extends java.util.SortedMap

A SortedMap extended with navigation methods returning the closest matches for given search targets. Methods , , , and return objects associated with keys respectively less than, less than or equal, greater than or equal, and greater than a given key, returning if there is no such key. Similarly, methods , , , and return only the associated keys. All of these methods are designed for locating, not traversing entries.

A may be accessed and traversed in either ascending or descending key order. The 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 , , and differ from the like-named methods in accepting additional arguments describing whether lower and upper bounds are inclusive versus exclusive. Submaps of any must implement the interface.

This interface additionally defines methods , , , and that return and/or remove the least and greatest mappings, if any exist, else returning .

Implementations of entry-returning methods are expected to return pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional method. Note however that it is possible to change mappings in the associated map using method .

Methods subMap(K, K), headMap(K), and tailMap(K) are specified to return to allow existing implementations of to be compatibly retrofitted to implement , but extensions and implementations of this interface are encouraged to override these methods to return . Similarly, Map.keySet() can be overriden to return .

This interface is a member of the Java Collections Framework.

Since:

1.6

Author:

Doug Lea, Josh Bloch

Nested Class Summary

Nested classes inherited from class java.util.Map

java.util.Map.Entry

Method Summary

java.util.Map.Entry	ceilingEntry(java.lang.Object key) Returns a key-value mapping associated with the least key greater than or equal to the given key, or if there is no such key.
java.lang.Object	ceilingKey(java.lang.Object key) Returns the least key greater than or equal to the given key, or 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.
java.util.Map.Entry	firstEntry() Returns a key-value mapping associated with the least key in this map, or if the map is empty.
java.util.Map.Entry	floorEntry(java.lang.Object key) Returns a key-value mapping associated with the greatest key less than or equal to the given key, or if there is no such key.
java.lang.Object	floorKey(java.lang.Object key) Returns the greatest key less than or equal to the given key, or if there is no such key.
java.util.SortedMap	headMap(java.lang.Object toKey)
NavigableMap	headMap(java.lang.Object toKey, boolean inclusive) Returns a view of the portion of this map whose keys are less than (or equal to, if is true) .
java.util.Map.Entry	higherEntry(java.lang.Object key) Returns a key-value mapping associated with the least key strictly greater than the given key, or if there is no such key.
java.lang.Object	higherKey(java.lang.Object key) Returns the least key strictly greater than the given key, or if there is no such key.
java.util.Map.Entry	lastEntry() Returns a key-value mapping associated with the greatest key in this map, or if the map is empty.
java.util.Map.Entry	lowerEntry(java.lang.Object key) Returns a key-value mapping associated with the greatest key strictly less than the given key, or if there is no such key.
java.lang.Object	lowerKey(java.lang.Object key) Returns the greatest key strictly less than the given key, or if there is no such key.
NavigableSet	navigableKeySet() Returns a NavigableSet view of the keys contained in this map.
java.util.Map.Entry	pollFirstEntry() Removes and returns a key-value mapping associated with the least key in this map, or if the map is empty.
java.util.Map.Entry	pollLastEntry() Removes and returns a key-value mapping associated with the greatest key in this map, or if the map is empty.
NavigableMap	subMap(java.lang.Object fromKey, boolean fromInclusive, java.lang.Object toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range from to .
java.util.SortedMap	subMap(java.lang.Object fromKey, java.lang.Object toKey)
java.util.SortedMap	tailMap(java.lang.Object fromKey)
NavigableMap	tailMap(java.lang.Object fromKey, boolean inclusive) Returns a view of the portion of this map whose keys are greater than (or equal to, if is true) .

Methods inherited from interface java.util.SortedMap

comparator, firstKey, lastKey

Methods inherited from interface java.util.Map

clear, containsKey, containsValue, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values

Method Detail

lowerEntry

public java.util.Map.Entry lowerEntry(java.lang.Object key)

Returns a key-value mapping associated with the greatest key strictly less than the given key, or if there is no such key.

Parameters:

key - the key

Returns:

an entry with the greatest key less than , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

lowerKey

public java.lang.Object lowerKey(java.lang.Object key)

Returns the greatest key strictly less than the given key, or if there is no such key.

Parameters:

key - the key

Returns:

the greatest key less than , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

floorEntry

public java.util.Map.Entry floorEntry(java.lang.Object key)

Returns a key-value mapping associated with the greatest key less than or equal to the given key, or if there is no such key.

Parameters:

key - the key

Returns:

an entry with the greatest key less than or equal to , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

floorKey

public java.lang.Object floorKey(java.lang.Object key)

Returns the greatest key less than or equal to the given key, or if there is no such key.

Parameters:

key - the key

Returns:

the greatest key less than or equal to , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

ceilingEntry

public java.util.Map.Entry ceilingEntry(java.lang.Object key)

Returns a key-value mapping associated with the least key greater than or equal to the given key, or if there is no such key.

Parameters:

key - the key

Returns:

an entry with the least key greater than or equal to , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

ceilingKey

public java.lang.Object ceilingKey(java.lang.Object key)

Returns the least key greater than or equal to the given key, or if there is no such key.

Parameters:

key - the key

Returns:

the least key greater than or equal to , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

higherEntry

public java.util.Map.Entry higherEntry(java.lang.Object key)

Returns a key-value mapping associated with the least key strictly greater than the given key, or if there is no such key.

Parameters:

key - the key

Returns:

an entry with the least key greater than , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

higherKey

public java.lang.Object higherKey(java.lang.Object key)

Returns the least key strictly greater than the given key, or if there is no such key.

Parameters:

key - the key

Returns:

the least key greater than , or if there is no such key

Throws:

java.lang.ClassCastException - if the specified key cannot be compared with the keys currently in the map

java.lang.NullPointerException - if the specified key is null and this map does not permit null keys

firstEntry

public java.util.Map.Entry firstEntry()

Returns a key-value mapping associated with the least key in this map, or if the map is empty.

Returns:

an entry with the least key, or if this map is empty

lastEntry

public java.util.Map.Entry lastEntry()

Returns a key-value mapping associated with the greatest key in this map, or if the map is empty.

Returns:

an entry with the greatest key, or if this map is empty

pollFirstEntry

public java.util.Map.Entry pollFirstEntry()

Removes and returns a key-value mapping associated with the least key in this map, or if the map is empty.

Returns:

the removed first entry of this map, or if this map is empty

pollLastEntry

public java.util.Map.Entry pollLastEntry()

Removes and returns a key-value mapping associated with the greatest key in this map, or if the map is empty.

Returns:

the removed last entry of this map, or if this map is empty

descendingMap

public NavigableMap 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 operation), the results of the iteration are undefined.

The returned map has an ordering equivalent to Collections.reverseOrder(comparator()). The expression returns a view of essentially equivalent to .

Returns:

a reverse order view of this map

navigableKeySet

public NavigableSet 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 operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the , , , , and operations. It does not support the or operations.

Returns:

a navigable set view of the keys in this map

descendingKeySet

public NavigableSet 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 operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the , , , , and operations. It does not support the or operations.

Returns:

a reverse order navigable set view of the keys in this map

subMap

public NavigableMap subMap(java.lang.Object fromKey,
                           boolean fromInclusive,
                           java.lang.Object toKey,
                           boolean toInclusive)

Returns a view of the portion of this map whose keys range from to . If and are equal, the returned map is empty unless and 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 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 - if the low endpoint is to be included in the returned view

toKey - high endpoint of the keys in the returned map

toInclusive - 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 to

Throws:

java.lang.ClassCastException - if and 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 or cannot be compared to keys currently in the map.

java.lang.NullPointerException - if or is null and this map does not permit null keys

java.lang.IllegalArgumentException - if is greater than ; or if this map itself has a restricted range, and or lies outside the bounds of the range

headMap

public NavigableMap headMap(java.lang.Object toKey,
                            boolean inclusive)

Returns a view of the portion of this map whose keys are less than (or equal to, if is 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 on an attempt to insert a key outside its range.

Parameters:

toKey - high endpoint of the keys in the returned map

inclusive - 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 is true)

Throws:

java.lang.ClassCastException - if is not compatible with this map's comparator (or, if the map has no comparator, if does not implement Comparable). Implementations may, but are not required to, throw this exception if cannot be compared to keys currently in the map.

java.lang.NullPointerException - if is null and this map does not permit null keys

java.lang.IllegalArgumentException - if this map itself has a restricted range, and lies outside the bounds of the range

tailMap

public NavigableMap tailMap(java.lang.Object fromKey,
                            boolean inclusive)

Returns a view of the portion of this map whose keys are greater than (or equal to, if is 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 on an attempt to insert a key outside its range.

Parameters:

fromKey - low endpoint of the keys in the returned map

inclusive - 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 is true)

Throws:

java.lang.ClassCastException - if is not compatible with this map's comparator (or, if the map has no comparator, if does not implement Comparable). Implementations may, but are not required to, throw this exception if cannot be compared to keys currently in the map.

java.lang.NullPointerException - if is null and this map does not permit null keys

java.lang.IllegalArgumentException - if this map itself has a restricted range, and lies outside the bounds of the range

subMap

public java.util.SortedMap subMap(java.lang.Object fromKey,
                                  java.lang.Object toKey)

Equivalent to .

Specified by:

subMap in interface java.util.SortedMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException

java.lang.IllegalArgumentException

headMap

public java.util.SortedMap headMap(java.lang.Object toKey)

Equivalent to .

Specified by:

headMap in interface java.util.SortedMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException

java.lang.IllegalArgumentException

tailMap

public java.util.SortedMap tailMap(java.lang.Object fromKey)

Equivalent to .

Specified by:

tailMap in interface java.util.SortedMap

Throws:

java.lang.ClassCastException

java.lang.NullPointerException

java.lang.IllegalArgumentException