Added in API level 9

NavigableMap

interface NavigableMap<K : Any!, V : Any!> : SortedMap<K, V>

java.util.NavigableMap

Known Direct Subclasses

ConcurrentNavigableMap, TreeMap

ConcurrentNavigableMap	A `ConcurrentMap` supporting `NavigableMap` operations, and recursively so for its navigable sub-maps.
TreeMap	A Red-Black tree based `NavigableMap` implementation.

Known Indirect Subclasses

ConcurrentSkipListMap

A scalable concurrent ConcurrentNavigableMap implementation.

A SortedMap extended with navigation methods returning the closest matches for given search targets. Methods 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, 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(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, firstEntry, floorEntry, higherEntry, lastEntry, lowerEntry, 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, keySet() can be overridden to return NavigableSet.

Summary

Public methods
abstract MutableEntry<K, V>?	`ceilingEntry(key: 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.
abstract K?	`ceilingKey(key: K)` Returns the least key greater than or equal to the given key, or `null` if there is no such key.
abstract NavigableSet<K>	`descendingKeySet()` Returns a reverse order `NavigableSet` view of the keys contained in this map.
abstract NavigableMap<K, V>	`descendingMap()` Returns a reverse order view of the mappings contained in this map.
abstract MutableEntry<K, V>?	`firstEntry()` Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
abstract MutableEntry<K, V>?	`floorEntry(key: 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.
abstract K?	`floorKey(key: K)` Returns the greatest key less than or equal to the given key, or `null` if there is no such key.
abstract SortedMap<K, V>	`headMap(toKey: K)` Returns a view of the portion of this map whose keys are strictly less than `toKey`.
abstract NavigableMap<K, V>	`headMap(toKey: K, inclusive: Boolean)` Returns a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`.
abstract MutableEntry<K, V>?	`higherEntry(key: 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.
abstract K?	`higherKey(key: K)` Returns the least key strictly greater than the given key, or `null` if there is no such key.
abstract MutableEntry<K, V>?	`lastEntry()` Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
abstract MutableEntry<K, V>?	`lowerEntry(key: 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.
abstract K?	`lowerKey(key: K)` Returns the greatest key strictly less than the given key, or `null` if there is no such key.
abstract NavigableSet<K>	`navigableKeySet()` Returns a `NavigableSet` view of the keys contained in this map.
abstract MutableEntry<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.
abstract MutableEntry<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.
open NavigableMap<K, V>	`reversed()` Returns a reverse-ordered view of this map.
abstract NavigableMap<K, V>	`subMap(fromKey: K, fromInclusive: Boolean, toKey: K, toInclusive: Boolean)` Returns a view of the portion of this map whose keys range from `fromKey` to `toKey`.
abstract SortedMap<K, V>	`subMap(fromKey: K, toKey: K)` Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive.
abstract SortedMap<K, V>	`tailMap(fromKey: K)` Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`.
abstract NavigableMap<K, V>	`tailMap(fromKey: K, inclusive: Boolean)` Returns a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`.

Inherited functions

From class SortedMap

`Comparator<in K>?`	`comparator()` Returns the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys.
`K`	`firstKey()` Returns the first (lowest) key currently in this map.
`K`	`lastKey()` Returns the last (highest) key currently in this map.
`V?`	`putFirst(k: K, v: V)` Throws `UnsupportedOperationException`. The encounter order induced by this map's comparison method determines the position of mappings, so explicit positioning is not supported.
`V?`	`putLast(k: K, v: V)` Throws `UnsupportedOperationException`. The encounter order induced by this map's comparison method determines the position of mappings, so explicit positioning is not supported.

From class SequencedMap

`MutableEntry<K, V>!`	`firstEntry()` Returns the first key-value mapping in this map, or `null` if the map is empty.
`MutableEntry<K, V>!`	`lastEntry()` Returns the last key-value mapping in this map, or `null` if the map is empty.
`MutableEntry<K, V>!`	`pollFirstEntry()` Removes and returns the first key-value mapping in this map, or `null` if the map is empty (optional operation).
`MutableEntry<K, V>!`	`pollLastEntry()` Removes and returns the last key-value mapping in this map, or `null` if the map is empty (optional operation).
`SequencedSet<MutableEntry<K, V>!>!`	`sequencedEntrySet()` Returns a `SequencedSet` view of this map's `entrySet`.
`SequencedSet<K>!`	`sequencedKeySet()` Returns a `SequencedSet` view of this map's `keySet`.
`SequencedCollection<V>!`	`sequencedValues()` Returns a `SequencedCollection` view of this map's `values` collection.

Inherited properties

From class SortedMap

MutableSet<MutableEntry<K, V>>

entries

Returns a Set view of the mappings contained in this map. The set's iterator returns the entries in ascending key 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, or through the setValue operation on a map entry returned by the iterator) 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.

MutableSet<K>

keys

Returns a Set 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.

MutableCollection<V>

values

Returns a Collection view of the values contained in this map. The collection's iterator returns the values in ascending order of the corresponding keys. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Public methods

ceilingEntry

Added in API level 9

abstract fun ceilingEntry(key: K): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the least key greater than or equal to `key`, or `null` if there is no such key

Exceptions
`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

Added in API level 9

abstract fun ceilingKey(key: K): K?

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

Return
`K?`	the least key greater than or equal to `key`, or `null` if there is no such key

Exceptions
`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

descendingKeySet

Added in API level 9

abstract fun descendingKeySet(): NavigableSet<K>

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.

Return
`NavigableSet<K>`	a reverse order navigable set view of the keys in this map

descendingMap

Added in API level 9

abstract fun descendingMap(): NavigableMap<K, V>

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.

Return
`NavigableMap<K, V>`	a reverse order view of this map

firstEntry

Added in API level 9

abstract fun firstEntry(): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the least key, or `null` if this map is empty

floorEntry

Added in API level 9

abstract fun floorEntry(key: K): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the greatest key less than or equal to `key`, or `null` if there is no such key

Exceptions
`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

Added in API level 9

abstract fun floorKey(key: K): K?

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

Return
`K?`	the greatest key less than or equal to `key`, or `null` if there is no such key

Exceptions
`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

headMap

Added in API level 9

abstract fun headMap(toKey: K): SortedMap<K, V>

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

Return
`SortedMap<K, V>`	a view of the portion of this map whose keys are strictly less than `toKey`

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `toKey` is null and this map does not permit null keys
`java.lang.IllegalArgumentException`	if this map itself has a restricted range, and `toKey` lies outside the bounds of the range

headMap

Added in API level 9

abstract fun headMap(
    toKey: K, 
    inclusive: Boolean
): NavigableMap<K, V>

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

Return
`NavigableMap<K, V>`	a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `toKey` is null and this map does not permit null keys
`java.lang.IllegalArgumentException`	if this map itself has a restricted range, and `toKey` lies outside the bounds of the range

higherEntry

Added in API level 9

abstract fun higherEntry(key: K): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the least key greater than `key`, or `null` if there is no such key

Exceptions
`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

Added in API level 9

abstract fun higherKey(key: K): K?

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

Parameters
`key`	K: the key

Return
`K?`	the least key greater than `key`, or `null` if there is no such key

Exceptions
`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

lastEntry

Added in API level 9

abstract fun lastEntry(): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the greatest key, or `null` if this map is empty

lowerEntry

Added in API level 9

abstract fun lowerEntry(key: K): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	an entry with the greatest key less than `key`, or `null` if there is no such key

Exceptions
`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

Added in API level 9

abstract fun lowerKey(key: K): K?

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

Parameters
`key`	K: the key

Return
`K?`	the greatest key less than `key`, or `null` if there is no such key

Exceptions
`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

navigableKeySet

Added in API level 9

abstract fun navigableKeySet(): NavigableSet<K>

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.

Return
`NavigableSet<K>`	a navigable set view of the keys in this map

pollFirstEntry

Added in API level 9

abstract fun pollFirstEntry(): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	the removed first entry of this map, or `null` if this map is empty

Exceptions
`java.lang.UnsupportedOperationException`	if this collection implementation does not support this operation

pollLastEntry

Added in API level 9

abstract fun pollLastEntry(): MutableEntry<K, V>?

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

Return
`MutableEntry<K, V>?`	the removed last entry of this map, or `null` if this map is empty

Exceptions
`java.lang.UnsupportedOperationException`	if this collection implementation does not support this operation

reversed

Added in API level 35

open fun reversed(): NavigableMap<K, V>

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.

Return
`NavigableMap<K, V>`	a reverse-ordered view of this map, as a `NavigableMap`

subMap

Added in API level 9

abstract fun subMap(
    fromKey: K, 
    fromInclusive: Boolean, 
    toKey: K, 
    toInclusive: Boolean
): NavigableMap<K, V>

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

Return
`NavigableMap<K, V>`	a view of the portion of this map whose keys range from `fromKey` to `toKey`

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `fromKey` or `toKey` is null and this map does not permit null keys
`java.lang.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

subMap

Added in API level 9

abstract fun subMap(
    fromKey: K, 
    toKey: K
): SortedMap<K, V>

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

Return
`SortedMap<K, V>`	a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `fromKey` or `toKey` is null and this map does not permit null keys
`java.lang.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

tailMap

Added in API level 9

abstract fun tailMap(fromKey: K): SortedMap<K, V>

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

Return
`SortedMap<K, V>`	a view of the portion of this map whose keys are greater than or equal to `fromKey`

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `fromKey` is null and this map does not permit null keys
`java.lang.IllegalArgumentException`	if this map itself has a restricted range, and `fromKey` lies outside the bounds of the range

tailMap

Added in API level 9

abstract fun tailMap(
    fromKey: K, 
    inclusive: Boolean
): NavigableMap<K, V>

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

Return
`NavigableMap<K, V>`	a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`

Exceptions
`java.lang.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.
`java.lang.NullPointerException`	if `fromKey` is null and this map does not permit null keys
`java.lang.IllegalArgumentException`	if this map itself has a restricted range, and `fromKey` lies outside the bounds of the range