Added in API level 9

ConcurrentSkipListMap

open class ConcurrentSkipListMap<K : Any!, V : Any!> : AbstractMap<K, V>, ConcurrentNavigableMap<K, V>, Cloneable, Serializable, MutableMap<K, V>

kotlin.Any
↳	java.util.AbstractMap<K, V>
	↳	java.util.concurrent.ConcurrentSkipListMap

A scalable concurrent ConcurrentNavigableMap implementation. The map is sorted according to the ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.

This class implements a concurrent variant of SkipLists providing expected average log(n) time cost for the containsKey, get, put and remove operations and their variants. Insertion, removal, update, and access operations safely execute concurrently by multiple threads.

Iterators and spliterators are weakly consistent.

Ascending key ordered views and their iterators are faster than descending ones.

All Map.Entry pairs returned by methods in this class and its views represent snapshots of mappings at the time they were produced. They do not support the Entry.setValue method. (Note however that it is possible to change mappings in the associated map using put, putIfAbsent, or replace, depending on exactly which effect you need.)

Beware that bulk operations putAll, equals, toArray, containsValue, and clear are not guaranteed to be performed atomically. For example, an iterator operating concurrently with a putAll operation might view only some of the added elements.

This class and its views and iterators implement all of the optional methods of the Map and Iterator interfaces. Like most other concurrent collections, this class does not permit the use of null keys or values because some null return values cannot be reliably distinguished from the absence of elements.

This class is a member of the Java Collections Framework.

Summary

Public constructors
`ConcurrentSkipListMap()` Constructs a new, empty map, sorted according to the natural ordering of the keys.
`ConcurrentSkipListMap(comparator: Comparator<in K>!)` Constructs a new, empty map, sorted according to the specified comparator.
`ConcurrentSkipListMap(m: MutableMap<out K, out V>!)` Constructs a new map containing the same mappings as the given map, sorted according to the natural ordering of the keys.
`ConcurrentSkipListMap(m: SortedMap<K, out V>!)` Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.

Public methods
open 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 entry.
open K?	`ceilingKey(key: K)`
open Unit	`clear()` Removes all of the mappings from this map.
open ConcurrentSkipListMap<K, V>	`clone()` Returns a shallow copy of this `ConcurrentSkipListMap` instance.
open Comparator<in K>?	`comparator()`
open V?	`compute(key: K, remappingFunction: BiFunction<in K, in V?, out V?>)` Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping).
open V	`computeIfAbsent(key: K, mappingFunction: Function<in K, out V>)` If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless `null`.
open V?	`computeIfPresent(key: K, remappingFunction: BiFunction<in K, in V, out V?>)` If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value.
open Boolean	`containsKey(key: K)` Returns `true` if this map contains a mapping for the specified key.
open Boolean	`containsKey(key: K)` Returns `true` if this map contains a mapping for the specified key.
open Boolean	`containsValue(value: V)` Returns `true` if this map maps one or more keys to the specified value.
open Boolean	`containsValue(value: V)` Returns `true` if this map maps one or more keys to the specified value.
open NavigableSet<K>	`descendingKeySet()`
open ConcurrentNavigableMap<K, V>	`descendingMap()`
open Boolean	`equals(other: Any?)` Compares the specified object with this map for equality.
open MutableEntry<K, V>?	`firstEntry()` Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
open K	`firstKey()`
open 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.
open K?	`floorKey(key: K)`
open Unit	`forEach(action: BiConsumer<in K, in V>)`
open V?	`get(key: K)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
open V?	`get(key: K)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
open V	`getOrDefault(key: K, defaultValue: V)` Returns the value to which the specified key is mapped, or the given defaultValue if this map contains no mapping for the key.
open ConcurrentNavigableMap<K, V>	`headMap(toKey: K, inclusive: Boolean)`
open ConcurrentNavigableMap<K, V>	`headMap(toKey: K)`
open 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.
open K?	`higherKey(key: K)`
open Boolean	`isEmpty()` Returns `true` if this map contains no key-value mappings.
open MutableEntry<K, V>?	`lastEntry()` Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
open K	`lastKey()`
open 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.
open K?	`lowerKey(key: K)`
open V?	`merge(key: K, value: V, remappingFunction: BiFunction<in V, in V, out V?>)` If the specified key is not already associated with a value, associates it with the given value.
open NavigableSet<K>	`navigableKeySet()`
open 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.
open 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 V?	`put(key: K, value: V)` Associates the specified value with the specified key in this map.
open V?	`putFirst(k: K, v: V)` Throws `UnsupportedOperationException`.
open V?	`putIfAbsent(key: K, value: V)` If the specified key is not already associated with a value (or is mapped to `null`) associates it with the given value and returns `null`, else returns the current value.
open V?	`putLast(k: K, v: V)` Throws `UnsupportedOperationException`.
open V?	`remove(key: K)` Removes the mapping for the specified key from this map if present.
open Boolean	`remove(key: K, value: V)` Removes the entry for the specified key only if it is currently mapped to the specified value.
open V?	`remove(key: K)` Removes the mapping for the specified key from this map if present.
open Boolean	`replace(key: K, oldValue: V, newValue: V)` Replaces the entry for the specified key only if currently mapped to the specified value.
open V?	`replace(key: K, value: V)` Replaces the entry for the specified key only if it is currently mapped to some value.
open Unit	`replaceAll(function: BiFunction<in K, in V, out V>)`
open ConcurrentNavigableMap<K, V>	`subMap(fromKey: K, fromInclusive: Boolean, toKey: K, toInclusive: Boolean)`
open ConcurrentNavigableMap<K, V>	`subMap(fromKey: K, toKey: K)`
open ConcurrentNavigableMap<K, V>	`tailMap(fromKey: K, inclusive: Boolean)`
open ConcurrentNavigableMap<K, V>	`tailMap(fromKey: K)`

Inherited functions

From class AbstractMap

Int

hashCode()

Returns the hash code value for this map. The hash code of a map is defined to be the sum of the hash codes of each entry in the map's entrySet() view. This ensures that m1.equals(m2) implies that m1.hashCode()==m2.hashCode() for any two maps m1 and m2, as required by the general contract of Object#hashCode.

Unit

putAll(from: Map<out K, V>)

Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

String

toString()

Returns a string representation of this map. The string representation consists of a list of key-value mappings in the order returned by the map's entrySet view's iterator, enclosed in braces ("{}"). Adjacent mappings are separated by the characters ", " (comma and space). Each key-value mapping is rendered as the key followed by an equals sign ("=") followed by the associated value. Keys and values are converted to strings as by String#valueOf(Object).

Properties
open MutableSet<MutableEntry<K, V>>	`entries` Returns a `Set` view of the mappings contained in this map.
open NavigableSet<K>	`keys` Returns a `NavigableSet` view of the keys contained in this map.
open Int	`size` Returns the number of key-value mappings in this map.
open MutableCollection<V>	`values` Returns a `Collection` view of the values contained in this map.

Public constructors

ConcurrentSkipListMap

Added in API level 9

ConcurrentSkipListMap()

Constructs a new, empty map, sorted according to the natural ordering of the keys.

ConcurrentSkipListMap

Added in API level 9

ConcurrentSkipListMap(comparator: Comparator<in K>!)

Constructs a new, empty map, sorted according to the specified comparator.

Parameters
`comparator`	Comparator<in K>!: the comparator that will be used to order this map. If `null`, the ordering of the keys will be used.

ConcurrentSkipListMap

Added in API level 9

ConcurrentSkipListMap(m: MutableMap<out K, out V>!)

Constructs a new map containing the same mappings as the given map, sorted according to the natural ordering of the keys.

Parameters
`m`	MutableMap<out K, out V>!: the map whose mappings are to be placed in this map

Exceptions
`java.lang.ClassCastException`	if the keys in `m` are not `Comparable`, or are not mutually comparable
`java.lang.NullPointerException`	if the specified map or any of its keys or values are null

ConcurrentSkipListMap

Added in API level 9

ConcurrentSkipListMap(m: SortedMap<K, out V>!)

Constructs a new map containing the same mappings and using the same ordering as the specified sorted map.

Parameters
`m`	SortedMap<K, out V>!: the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map

Exceptions
`java.lang.NullPointerException`	if the specified sorted map or any of its keys or values are null

Public methods

ceilingEntry

Added in API level 9

open 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 entry. The returned entry does not support the Entry.setValue method.

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

ceilingKey

Added in API level 9

open fun ceilingKey(key: K): K?

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

clear

Added in API level 9

open fun clear(): Unit

Removes all of the mappings from this map.

Exceptions
`java.lang.UnsupportedOperationException`	if the `clear` operation is not supported by this map

clone

Added in API level 9

open fun clone(): ConcurrentSkipListMap<K, V>

Returns a shallow copy of this ConcurrentSkipListMap instance. (The keys and values themselves are not cloned.)

Return
`ConcurrentSkipListMap<K, V>`	a shallow copy of this map

Exceptions
`java.lang.CloneNotSupportedException`	if the object's class does not support the `Cloneable` interface. Subclasses that override the `clone` method can also throw this exception to indicate that an instance cannot be cloned.

comparator

Added in API level 9

open fun comparator(): Comparator<in K>?

Return
`Comparator<in K>?`	the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys

compute

Added in API level 24

open fun compute(
    key: K, 
    remappingFunction: BiFunction<in K, in V?, out V?>
): V?

Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). The function is NOT guaranteed to be applied once atomically.

Parameters
`key`	K: key with which the specified value is to be associated
`remappingFunction`	BiFunction<in K, in V?, out V?>: the function to compute a value

Return
`V?`	the new value associated with the specified key, or null if none

Exceptions
`java.lang.NullPointerException`	if the specified key is null or the remappingFunction is null
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map (optional)
`java.lang.ClassCastException`	if the class of the specified key or value prevents it from being stored in this map (optional)
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map (optional)

computeIfAbsent

Added in API level 24

open fun computeIfAbsent(
    key: K, 
    mappingFunction: Function<in K, out V>
): V

If the specified key is not already associated with a value, attempts to compute its value using the given mapping function and enters it into this map unless null. The function is NOT guaranteed to be applied once atomically only if the value is not present.

Parameters
`key`	K: key with which the specified value is to be associated
`mappingFunction`	Function<in K, out V>: the function to compute a value

Return
`V`	the current (existing or computed) value associated with the specified key, or null if the computed value is null

Exceptions
`java.lang.NullPointerException`	if the specified key is null or the mappingFunction is null
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map (optional)
`java.lang.ClassCastException`	if the class of the specified key or value prevents it from being stored in this map (optional)
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map (optional)

computeIfPresent

Added in API level 24

open fun computeIfPresent(
    key: K, 
    remappingFunction: BiFunction<in K, in V, out V?>
): V?

If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value. The function is NOT guaranteed to be applied once atomically.

Parameters
`key`	K: key with which a value may be associated
`remappingFunction`	BiFunction<in K, in V, out V?>: the function to compute a value

Return
`V?`	the new value associated with the specified key, or null if none

Exceptions
`java.lang.NullPointerException`	if the specified key is null or the remappingFunction is null
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map (optional)
`java.lang.ClassCastException`	if the class of the specified key or value prevents it from being stored in this map (optional)
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map (optional)

containsKey

Added in API level 9

open fun containsKey(key: K): Boolean

Returns true if this map contains a mapping for the specified key.

Parameters
`key`	K: key whose presence in this map is to be tested

Return
`Boolean`	`true` if this map contains a mapping for the specified 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

containsKey

Added in API level 9

open fun containsKey(key: K): Boolean

Returns true if this map contains a mapping for the specified key.

Parameters
`key`	K: key whose presence in this map is to be tested

Return
`Boolean`	`true` if this map contains a mapping for the specified 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

containsValue

Added in API level 9

open fun containsValue(value: V): Boolean

Returns true if this map maps one or more keys to the specified value. This operation requires time linear in the map size. Additionally, it is possible for the map to change during execution of this method, in which case the returned result may be inaccurate.

Parameters
`value`	V: value whose presence in this map is to be tested

Return
`Boolean`	`true` if a mapping to `value` exists; `false` otherwise

Exceptions
`java.lang.ClassCastException`	if the value is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified value is null

containsValue

Added in API level 9

open fun containsValue(value: V): Boolean

Parameters
`value`	V: value whose presence in this map is to be tested

Return
`Boolean`	`true` if a mapping to `value` exists; `false` otherwise

Exceptions
`java.lang.ClassCastException`	if the value is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified value is null

descendingKeySet

Added in API level 9

open fun descendingKeySet(): NavigableSet<K>

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

descendingMap

Added in API level 9

open fun descendingMap(): ConcurrentNavigableMap<K, V>

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

equals

Added in API level 9

open fun equals(other: Any?): Boolean

Compares the specified object with this map for equality. Returns true if the given object is also a map and the two maps represent the same mappings. More formally, two maps m1 and m2 represent the same mappings if m1.entrySet().equals(m2.entrySet()). This operation may return misleading results if either map is concurrently modified during execution of this method.

Parameters
`obj`	the reference object with which to compare.
`o`	object to be compared for equality with this map

Return
`Boolean`	`true` if the specified object is equal to this map

firstEntry

Added in API level 9

open 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. The returned entry does not support the Entry.setValue method.

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

firstKey

Added in API level 9

open fun firstKey(): K

Return
`K`	the first (lowest) key currently in this map

Exceptions
`java.util.NoSuchElementException`	if this map is empty

floorEntry

Added in API level 9

open 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. The returned entry does not support the Entry.setValue method.

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

floorKey

Added in API level 9

open fun floorKey(key: K): K?

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

forEach

Added in API level 24

open fun forEach(action: BiConsumer<in K, in V>): Unit

Parameters
`action`	BiConsumer<in K, in V>: The action to be performed for each entry

Exceptions
`java.lang.NullPointerException`	if the specified action is null
`java.util.ConcurrentModificationException`	if an entry is found to be removed during iteration

get

Added in API level 9

open fun get(key: K): V?

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

More formally, if this map contains a mapping from a key k to a value v such that key compares equal to k according to the map's ordering, then this method returns v; otherwise it returns null. (There can be at most one such mapping.)

Parameters
`key`	K: the key whose associated value is to be returned

Return
`V?`	the value to which the specified key is mapped, or `null` if this map contains no mapping for the 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

get

Added in API level 9

open fun get(key: K): V?

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

Parameters
`key`	K: the key whose associated value is to be returned

Return
`V?`	the value to which the specified key is mapped, or `null` if this map contains no mapping for the 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

getOrDefault

Added in API level 24

open fun getOrDefault(
    key: K, 
    defaultValue: V
): V

Returns the value to which the specified key is mapped, or the given defaultValue if this map contains no mapping for the key.

Parameters
`key`	K: the key
`defaultValue`	V: the value to return if this map contains no mapping for the given key

Return
`V`	the mapping for the key, if present; else the defaultValue

Exceptions
`java.lang.ClassCastException`	if the key is of an inappropriate type for this map (optional)
`java.lang.NullPointerException`	if the specified key is null

headMap

Added in API level 9

open fun headMap(
    toKey: K, 
    inclusive: Boolean
): ConcurrentNavigableMap<K, V>

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
`ConcurrentNavigableMap<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
`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

open fun headMap(toKey: K): ConcurrentNavigableMap<K, V>

Parameters
`toKey`	K: high endpoint (exclusive) of the keys in the returned map

Return
`ConcurrentNavigableMap<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
`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

open 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. The returned entry does not support the Entry.setValue method.

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

higherKey

Added in API level 9

open fun higherKey(key: K): K?

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

isEmpty

Added in API level 9

open fun isEmpty(): Boolean

Returns true if this map contains no key-value mappings.

Return
`Boolean`	`true` if this map contains no key-value mappings

lastEntry

Added in API level 9

open 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. The returned entry does not support the Entry.setValue method.

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

lastKey

Added in API level 9

open fun lastKey(): K

Return
`K`	the last (highest) key currently in this map

Exceptions
`java.util.NoSuchElementException`	if this map is empty

lowerEntry

Added in API level 9

open 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. The returned entry does not support the Entry.setValue method.

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

lowerKey

Added in API level 9

open fun lowerKey(key: K): K?

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

merge

Added in API level 24

open fun merge(
    key: K, 
    value: V, 
    remappingFunction: BiFunction<in V, in V, out V?>
): V?

If the specified key is not already associated with a value, associates it with the given value. Otherwise, replaces the value with the results of the given remapping function, or removes if null. The function is NOT guaranteed to be applied once atomically.

Parameters
`key`	K: key with which the specified value is to be associated
`value`	V: the value to use if absent
`remappingFunction`	BiFunction<in V, in V, out V?>: the function to recompute a value if present

Return
`V?`	the new value associated with the specified key, or null if none

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map (optional)
`java.lang.ClassCastException`	if the class of the specified key or value prevents it from being stored in this map (optional)
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map (optional)
`java.lang.NullPointerException`	if the specified key or value is null or the remappingFunction is null

navigableKeySet

Added in API level 9

open fun navigableKeySet(): NavigableSet<K>

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

pollFirstEntry

Added in API level 9

open 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. The returned entry does not support the Entry.setValue method.

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

open 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. The returned entry does not support the Entry.setValue method.

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

put

Added in API level 9

open fun put(
    key: K, 
    value: V
): V?

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced.

Parameters
`key`	K: key with which the specified value is to be associated
`value`	V: value to be associated with the specified key

Return
`V?`	the previous value associated with the specified key, or `null` if there was no mapping for the key

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map
`java.lang.ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`java.lang.NullPointerException`	if the specified key or value is null
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map

putFirst

Added in API level 35

open fun putFirst(
    k: K, 
    v: 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.

Parameters
`k`	K: the key
`v`	V: the value

Return
`V?`	the value previously associated with k, or null if none

Exceptions
`java.lang.UnsupportedOperationException`	always

putIfAbsent

Added in API level 9

open fun putIfAbsent(
    key: K, 
    value: V
): V?

If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.

Parameters
`key`	K: key with which the specified value is to be associated
`value`	V: value to be associated with the specified key

Return
`V?`	the previous value associated with the specified key, or `null` if there was no mapping for the key

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map
`java.lang.ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`java.lang.NullPointerException`	if the specified key or value is null
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map

putLast

Added in API level 35

open fun putLast(
    k: K, 
    v: 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.

Parameters
`k`	K: the key
`v`	V: the value

Return
`V?`	the value previously associated with k, or null if none

Exceptions
`java.lang.UnsupportedOperationException`	always

remove

Added in API level 9

open fun remove(key: K): V?

Removes the mapping for the specified key from this map if present.

Parameters
`key`	K: key for which mapping should be removed

Return
`V?`	the previous value associated with the specified key, or `null` if there was no mapping for the key

Exceptions
`java.lang.UnsupportedOperationException`	if the `remove` operation is not supported by this map
`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

remove

Added in API level 9

open fun remove(
    key: K, 
    value: V
): Boolean

Removes the entry for the specified key only if it is currently mapped to the specified value.

Parameters
`key`	K: key with which the specified value is associated
`value`	V: value expected to be associated with the specified key

Return
`Boolean`	`true` if the value was removed

Exceptions
`java.lang.UnsupportedOperationException`	if the `remove` operation is not supported by this map
`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

remove

Added in API level 9

open fun remove(key: K): V?

Removes the mapping for the specified key from this map if present.

Parameters
`key`	K: key for which mapping should be removed

Return
`V?`	the previous value associated with the specified key, or `null` if there was no mapping for the key

Exceptions
`java.lang.UnsupportedOperationException`	if the `remove` operation is not supported by this map
`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

replace

Added in API level 9

open fun replace(
    key: K, 
    oldValue: V, 
    newValue: V
): Boolean

Replaces the entry for the specified key only if currently mapped to the specified value.

Parameters
`key`	K: key with which the specified value is associated
`oldValue`	V: value expected to be associated with the specified key
`newValue`	V: value to be associated with the specified key

Return
`Boolean`	`true` if the value was replaced

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map
`java.lang.ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`java.lang.NullPointerException`	if any of the arguments are null
`java.lang.IllegalArgumentException`	if some property of a specified key or value prevents it from being stored in this map

replace

Added in API level 9

open fun replace(
    key: K, 
    value: V
): V?

Replaces the entry for the specified key only if it is currently mapped to some value.

Parameters
`key`	K: key with which the specified value is associated
`value`	V: value to be associated with the specified key

Return
`V?`	the previous value associated with the specified key, or `null` if there was no mapping for the key

Exceptions
`java.lang.UnsupportedOperationException`	if the `put` operation is not supported by this map
`java.lang.ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`java.lang.NullPointerException`	if the specified key or value is null
`java.lang.IllegalArgumentException`	if some property of the specified key or value prevents it from being stored in this map

replaceAll

Added in API level 24

open fun replaceAll(function: BiFunction<in K, in V, out V>): Unit

Parameters
`function`	BiFunction<in K, in V, out V>: the function to apply to each entry

Exceptions
`java.lang.UnsupportedOperationException`	if the `set` operation is not supported by this map's entry set iterator.
`java.lang.ClassCastException`	if the class of a replacement value prevents it from being stored in this map
`java.lang.NullPointerException`	if the specified function is null, or the specified replacement value is null, and this map does not permit null values
`java.lang.IllegalArgumentException`	if some property of a replacement value prevents it from being stored in this map (optional)
`java.util.ConcurrentModificationException`	if an entry is found to be removed during iteration

subMap

Added in API level 9

open fun subMap(
    fromKey: K, 
    fromInclusive: Boolean, 
    toKey: K, 
    toInclusive: Boolean
): ConcurrentNavigableMap<K, V>

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
`ConcurrentNavigableMap<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
`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

open fun subMap(
    fromKey: K, 
    toKey: K
): ConcurrentNavigableMap<K, V>

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
`ConcurrentNavigableMap<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
`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

open fun tailMap(
    fromKey: K, 
    inclusive: Boolean
): ConcurrentNavigableMap<K, V>

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
`ConcurrentNavigableMap<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
`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

open fun tailMap(fromKey: K): ConcurrentNavigableMap<K, V>

Parameters
`fromKey`	K: low endpoint (inclusive) of the keys in the returned map

Return
`ConcurrentNavigableMap<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
`java.lang.IllegalArgumentException`	if this map itself has a restricted range, and `fromKey` lies outside the bounds of the range

Properties

entries

Added in API level 9

open val entries: MutableSet<MutableEntry<K, V>>

Returns a Set view of the mappings contained in this map.

The set's iterator returns the entries in ascending key order. The set's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL, Spliterator#SORTED and Spliterator#ORDERED, with an encounter order that is ascending key order.

The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. 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.

The view's iterators and spliterators are weakly consistent.

The Map.Entry elements traversed by the iterator or spliterator do not support the setValue operation.

Return
`MutableSet<MutableEntry<K, V>>`	a set view of the mappings contained in this map, sorted in ascending key order

keys

Added in API level 9

open val keys: 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's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL, Spliterator#SORTED and Spliterator#ORDERED, with an encounter order that is ascending key order.

The spliterator's comparator is null if the map's comparator is null. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the map's comparator.

The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. 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.

The view's iterators and spliterators are weakly consistent.

This method is equivalent to method navigableKeySet.

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

size

Added in API level 9

open val size: Int

Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Return
`Int`	the number of key-value mappings in this map

values

Added in API level 9

open val values: MutableCollection<V>

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 collections's spliterator additionally reports Spliterator#CONCURRENT, Spliterator#NONNULL and Spliterator#ORDERED, with an encounter order that is 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. 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.

The view's iterators and spliterators are weakly consistent.

Return
`MutableCollection<V>`	a collection view of the values contained in this map, sorted in ascending key order