# ConcurrentSkipListMap

public class **ConcurrentSkipListMap** extends [AbstractMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html)\<K, V\>  
implements [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> [Cloneable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Cloneable.html) [Serializable](https://developers.google.com/j2objc/javadoc/jre/reference/java/io/Serializable.html) A scalable concurrent `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html` implementation.
The map is sorted according to the {@linkplain Comparable natural
ordering} of its keys, or by a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html` provided at map
creation time, depending on which constructor is used.

This class implements a concurrent variant of [SkipLists](http://en.wikipedia.org/wiki/Skip_list)
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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

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, unlike in most collections, the `size`
method is *not* a constant-time operation. Because of the
asynchronous nature of these maps, determining the current number
of elements requires a traversal of the elements, and so may report
inaccurate results if this collection is modified during traversal.
Additionally, the 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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html` and `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html`
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.

### Public Constructor Summary

|---|---|
|   | [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ConcurrentSkipListMap())() Constructs a new, empty map, sorted according to the {@linkplain Comparable natural ordering} of the keys. |
|   | [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ConcurrentSkipListMap(java.util.Comparator<?%20super%20K>))([Comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html)\<? super K\> comparator) Constructs a new, empty map, sorted according to the specified comparator. |
|   | [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ConcurrentSkipListMap(java.util.Map<?%20extends%20K,%20?%20extends%20V>))([Map](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html)\<? extends K, ? extends V\> m) Constructs a new map containing the same mappings as the given map, sorted according to the {@linkplain Comparable natural ordering} of the keys. |
|   | [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ConcurrentSkipListMap(java.util.SortedMap<K,%20?%20extends%20V>))([SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, ? extends V\> m) Constructs a new map containing the same mappings and using the same ordering as the specified sorted map. |

### Public Method Summary

|---|---|
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [ceilingEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ceilingEntry(K))(K key) Returns a key-value mapping associated with the least key greater than or equal to the given key, or `null` if there is no such entry. |
| K | [ceilingKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#ceilingKey(K))(K key) Returns the least key greater than or equal to the given key, or `null` if there is no such key. |
| void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#clear())() Removes all of the mappings from this map. |
| [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html)\<K, V\> | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#clone())() Returns a shallow copy of this `ConcurrentSkipListMap` instance. |
| [Comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html)\<? super K\> | [comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#comparator())() Returns the comparator used to order the keys in this map, or `null` if this map uses the {@linkplain Comparable natural ordering} of its keys. |
| V | [compute](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#compute(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping). |
| V | [computeIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#computeIfAbsent(K,%20java.util.function.Function<?%20super%20K,%20?%20extends%20V>))(K key, [Function](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Function.html)\<? super K, ? extends V\> mappingFunction) 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`. |
| V | [computeIfPresent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#computeIfPresent(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) If the value for the specified key is present, attempts to compute a new mapping given the key and its current mapped value. |
| boolean | [containsKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#containsKey(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns `true` if this map contains a mapping for the specified key. |
| boolean | [containsValue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#containsValue(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Returns `true` if this map maps one or more keys to the specified value. |
| [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [descendingKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#descendingKeySet())() Returns a reverse order `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [descendingMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#descendingMap())() Returns a reverse order view of the mappings contained in this map. |
| [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<[Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>\> | [entrySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#entrySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the mappings contained in this map. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Compares the specified object with this map for equality. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [firstEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#firstEntry())() Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty. |
| K | [firstKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#firstKey())() Returns the first (lowest) key currently in this map. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [floorEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#floorEntry(K))(K key) Returns a key-value mapping associated with the greatest key less than or equal to the given key, or `null` if there is no such key. |
| K | [floorKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#floorKey(K))(K key) Returns the greatest key less than or equal to the given key, or `null` if there is no such key. |
| void | [forEach](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#forEach(java.util.function.BiConsumer<?%20super%20K,%20?%20super%20V>))([BiConsumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiConsumer.html)\<? super K, ? super V\> action) Performs the given action for each entry in this map until all entries have been processed or the action throws an exception. |
| V | [get](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#get(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key. |
| V | [getOrDefault](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#getOrDefault(java.lang.Object,%20V))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, V defaultValue) Returns the value to which the specified key is mapped, or the given defaultValue if this map contains no mapping for the key. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#headMap(K))(K toKey) Returns a view of the portion of this map whose keys are strictly less than `toKey`. Equivalent to `headMap(toKey, false)`. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#headMap(K,%20boolean))(K toKey, boolean inclusive) Returns a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [higherEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#higherEntry(K))(K key) Returns a key-value mapping associated with the least key strictly greater than the given key, or `null` if there is no such key. |
| K | [higherKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#higherKey(K))(K key) Returns the least key strictly greater than the given key, or `null` if there is no such key. |
| boolean | [isEmpty](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#isEmpty())() Returns `true` if this map contains no key-value mappings. |
| [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [keySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#keySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [lastEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#lastEntry())() Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty. |
| K | [lastKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#lastKey())() Returns the last (highest) key currently in this map. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [lowerEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#lowerEntry(K))(K key) Returns a key-value mapping associated with the greatest key strictly less than the given key, or `null` if there is no such key. |
| K | [lowerKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#lowerKey(K))(K key) Returns the greatest key strictly less than the given key, or `null` if there is no such key. |
| V | [merge](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#merge(K,%20V,%20java.util.function.BiFunction<?%20super%20V,%20?%20super%20V,%20?%20extends%20V>))(K key, V value, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super V, ? super V, ? extends V\> remappingFunction) If the specified key is not already associated with a value, associates it with the given value. |
| [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [navigableKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#navigableKeySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [pollFirstEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#pollFirstEntry())() Removes and returns a key-value mapping associated with the least key in this map, or `null` if the map is empty. |
| [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [pollLastEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#pollLastEntry())() Removes and returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty. |
| V | [put](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#put(K,%20V))(K key, V value) Associates the specified value with the specified key in this map. |
| V | [putIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#putIfAbsent(K,%20V))(K key, V value) If the specified key is not already associated with a value, associates it with the given value. |
| boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#remove(java.lang.Object,%20java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Removes the entry for a key only if currently mapped to a given value. |
| V | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Removes the mapping for the specified key from this map if present. |
| boolean | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#replace(K,%20V,%20V))(K key, V oldValue, V newValue) Replaces the entry for a key only if currently mapped to a given value. |
| V | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#replace(K,%20V))(K key, V value) Replaces the entry for a key only if currently mapped to some value. |
| void | [replaceAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#replaceAll(java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))([BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> function) Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. |
| int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#size())() Returns the number of key-value mappings in this map. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#subMap(K,%20K))(K fromKey, K toKey) Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive. Equivalent to `subMap(fromKey, true, toKey, false)`. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#subMap(K,%20boolean,%20K,%20boolean))(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range from `fromKey` to `toKey`. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#tailMap(K,%20boolean))(K fromKey, boolean inclusive) Returns a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`. |
| [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#tailMap(K))(K fromKey) Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`. Equivalent to `tailMap(fromKey, true)`. |
| [Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\<V\> | [values](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#values())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` view of the values contained in this map. |

### Inherited Method Summary

From class [java.util.AbstractMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html)

|---|---|
| void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#clear())() Removes all of the mappings from this map (optional operation). |
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#clone())() Returns a shallow copy of this AbstractMap instance: the keys and values themselves are not cloned. |
| boolean | [containsKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#containsKey(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns `true` if this map contains a mapping for the specified key. |
| boolean | [containsValue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#containsValue(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Returns `true` if this map maps one or more keys to the specified value. |
| abstract [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<[Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>\> | [entrySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#entrySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the mappings contained in this map. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Compares the specified object with this map for equality. |
| V | [get](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#get(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#hashCode())() Returns the hash code value for this map. |
| boolean | [isEmpty](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#isEmpty())() Returns `true` if this map contains no key-value mappings. |
| [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<K\> | [keySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#keySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the keys contained in this map. |
| V | [put](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#put(K,%20V))(K key, V value) Associates the specified value with the specified key in this map (optional operation). |
| void | [putAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#putAll(java.util.Map<?%20extends%20K,%20?%20extends%20V>))([Map](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html)\<? extends K, ? extends V\> m) Copies all of the mappings from the specified map to this map (optional operation). |
| V | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Removes the mapping for a key from this map if it is present (optional operation). |
| int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#size())() Returns the number of key-value mappings in this map. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#toString())() Returns a string representation of this map. |
| [Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\<V\> | [values](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractMap.html#values())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` view of the values contained in this map. |

From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. |
| void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. |
| final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\<?\> | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. |
| final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. |

From interface [java.util.Map](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html)

|---|---|
| abstract void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#clear())() Removes all of the mappings from this map (optional operation). |
| V | [compute](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#compute(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping). |
| V | [computeIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#computeIfAbsent(K,%20java.util.function.Function<?%20super%20K,%20?%20extends%20V>))(K key, [Function](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Function.html)\<? super K, ? extends V\> mappingFunction) If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into this map unless `null`. |
| V | [computeIfPresent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#computeIfPresent(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value. |
| abstract boolean | [containsKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#containsKey(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns `true` if this map contains a mapping for the specified key. |
| abstract boolean | [containsValue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#containsValue(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Returns `true` if this map maps one or more keys to the specified value. |
| abstract [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<[Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>\> | [entrySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#entrySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the mappings contained in this map. |
| abstract boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Compares the specified object with this map for equality. |
| void | [forEach](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#forEach(java.util.function.BiConsumer<?%20super%20K,%20?%20super%20V>))([BiConsumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiConsumer.html)\<? super K, ? super V\> action) Performs the given action for each entry in this map until all entries have been processed or the action throws an exception. |
| abstract V | [get](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#get(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key. |
| V | [getOrDefault](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#getOrDefault(java.lang.Object,%20V))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, V defaultValue) Returns the value to which the specified key is mapped, or `defaultValue` if this map contains no mapping for the key. |
| abstract int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#hashCode())() Returns the hash code value for this map. |
| abstract boolean | [isEmpty](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#isEmpty())() Returns `true` if this map contains no key-value mappings. |
| abstract [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<K\> | [keySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#keySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the keys contained in this map. |
| V | [merge](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#merge(K,%20V,%20java.util.function.BiFunction<?%20super%20V,%20?%20super%20V,%20?%20extends%20V>))(K key, V value, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super V, ? super V, ? extends V\> remappingFunction) If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. |
| abstract V | [put](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#put(K,%20V))(K key, V value) Associates the specified value with the specified key in this map (optional operation). |
| abstract void | [putAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#putAll(java.util.Map<?%20extends%20K,%20?%20extends%20V>))([Map](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html)\<? extends K, ? extends V\> m) Copies all of the mappings from the specified map to this map (optional operation). |
| V | [putIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#putIfAbsent(K,%20V))(K key, V value) 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. |
| boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#remove(java.lang.Object,%20java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Removes the entry for the specified key only if it is currently mapped to the specified value. |
| abstract V | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key) Removes the mapping for a key from this map if it is present (optional operation). |
| boolean | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#replace(K,%20V,%20V))(K key, V oldValue, V newValue) Replaces the entry for the specified key only if currently mapped to the specified value. |
| V | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#replace(K,%20V))(K key, V value) Replaces the entry for the specified key only if it is currently mapped to some value. |
| void | [replaceAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#replaceAll(java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))([BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> function) Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. |
| abstract int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#size())() Returns the number of key-value mappings in this map. |
| abstract [Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\<V\> | [values](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html#values())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` view of the values contained in this map. |

From interface [java.util.concurrent.ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)

|---|---|
| abstract [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [descendingKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#descendingKeySet())() Returns a reverse order `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [descendingMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#descendingMap())() Returns a reverse order view of the mappings contained in this map. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#headMap(K))(K toKey) Returns a view of the portion of this map whose keys are strictly less than `toKey`. Equivalent to `headMap(toKey, false)`. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#headMap(K,%20boolean))(K toKey, boolean inclusive) Returns a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`. |
| abstract [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [keySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#keySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| abstract [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [navigableKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#navigableKeySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#subMap(K,%20K))(K fromKey, K toKey) Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive. Equivalent to `subMap(fromKey, true, toKey, false)`. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#subMap(K,%20boolean,%20K,%20boolean))(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range from `fromKey` to `toKey`. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#tailMap(K,%20boolean))(K fromKey, boolean inclusive) Returns a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`. |
| abstract [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html#tailMap(K))(K fromKey) Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`. Equivalent to `tailMap(fromKey, true)`. |

From interface [java.util.concurrent.ConcurrentMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html)

|---|---|
| V | [compute](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#compute(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (or `null` if there is no current mapping). |
| V | [computeIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#computeIfAbsent(K,%20java.util.function.Function<?%20super%20K,%20?%20extends%20V>))(K key, [Function](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Function.html)\<? super K, ? extends V\> mappingFunction) If the specified key is not already associated with a value (or is mapped to `null`), attempts to compute its value using the given mapping function and enters it into this map unless `null`. |
| V | [computeIfPresent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#computeIfPresent(K,%20java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction) If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value. |
| void | [forEach](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#forEach(java.util.function.BiConsumer<?%20super%20K,%20?%20super%20V>))([BiConsumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiConsumer.html)\<? super K, ? super V\> action) Performs the given action for each entry in this map until all entries have been processed or the action throws an exception. |
| V | [getOrDefault](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#getOrDefault(java.lang.Object,%20V))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, V defaultValue) Returns the value to which the specified key is mapped, or `defaultValue` if this map contains no mapping for the key. |
| V | [merge](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#merge(K,%20V,%20java.util.function.BiFunction<?%20super%20V,%20?%20super%20V,%20?%20extends%20V>))(K key, V value, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super V, ? super V, ? extends V\> remappingFunction) If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. |
| abstract V | [putIfAbsent](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#putIfAbsent(K,%20V))(K key, V value) If the specified key is not already associated with a value, associates it with the given value. |
| abstract boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#remove(java.lang.Object,%20java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value) Removes the entry for a key only if currently mapped to a given value. |
| abstract boolean | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#replace(K,%20V,%20V))(K key, V oldValue, V newValue) Replaces the entry for a key only if currently mapped to a given value. |
| abstract V | [replace](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#replace(K,%20V))(K key, V value) Replaces the entry for a key only if currently mapped to some value. |
| void | [replaceAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentMap.html#replaceAll(java.util.function.BiFunction<?%20super%20K,%20?%20super%20V,%20?%20extends%20V>))([BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> function) Replaces each entry's value with the result of invoking the given function on that entry until all entries have been processed or the function throws an exception. |

From interface [java.util.NavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html)

|---|---|
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [ceilingEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#ceilingEntry(K))(K key) Returns a key-value mapping associated with the least key greater than or equal to the given key, or `null` if there is no such key. |
| abstract K | [ceilingKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#ceilingKey(K))(K key) Returns the least key greater than or equal to the given key, or `null` if there is no such key. |
| abstract [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [descendingKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#descendingKeySet())() Returns a reverse order `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| abstract [NavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html)\<K, V\> | [descendingMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#descendingMap())() Returns a reverse order view of the mappings contained in this map. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [firstEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#firstEntry())() Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [floorEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#floorEntry(K))(K key) Returns a key-value mapping associated with the greatest key less than or equal to the given key, or `null` if there is no such key. |
| abstract K | [floorKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#floorKey(K))(K key) Returns the greatest key less than or equal to the given key, or `null` if there is no such key. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#headMap(K))(K toKey) Returns a view of the portion of this map whose keys are strictly less than `toKey`. Equivalent to `headMap(toKey, false)`. |
| abstract [NavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#headMap(K,%20boolean))(K toKey, boolean inclusive) Returns a view of the portion of this map whose keys are less than (or equal to, if `inclusive` is true) `toKey`. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [higherEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#higherEntry(K))(K key) Returns a key-value mapping associated with the least key strictly greater than the given key, or `null` if there is no such key. |
| abstract K | [higherKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#higherKey(K))(K key) Returns the least key strictly greater than the given key, or `null` if there is no such key. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [lastEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#lastEntry())() Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [lowerEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#lowerEntry(K))(K key) Returns a key-value mapping associated with the greatest key strictly less than the given key, or `null` if there is no such key. |
| abstract K | [lowerKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#lowerKey(K))(K key) Returns the greatest key strictly less than the given key, or `null` if there is no such key. |
| abstract [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\> | [navigableKeySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#navigableKeySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [pollFirstEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#pollFirstEntry())() Removes and returns a key-value mapping associated with the least key in this map, or `null` if the map is empty. |
| abstract [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\> | [pollLastEntry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#pollLastEntry())() Removes and returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#subMap(K,%20K))(K fromKey, K toKey) Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive. Equivalent to `subMap(fromKey, true, toKey, false)`. |
| abstract [NavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#subMap(K,%20boolean,%20K,%20boolean))(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range from `fromKey` to `toKey`. |
| abstract [NavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#tailMap(K,%20boolean))(K fromKey, boolean inclusive) Returns a view of the portion of this map whose keys are greater than (or equal to, if `inclusive` is true) `fromKey`. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableMap.html#tailMap(K))(K fromKey) Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`. Equivalent to `tailMap(fromKey, true)`. |

From interface [java.util.SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)

|---|---|
| abstract [Comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html)\<? super K\> | [comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#comparator())() Returns the comparator used to order the keys in this map, or `null` if this map uses the {@linkplain Comparable natural ordering} of its keys. |
| abstract [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<[Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>\> | [entrySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#entrySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the mappings contained in this map. |
| abstract K | [firstKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#firstKey())() Returns the first (lowest) key currently in this map. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [headMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#headMap(K))(K toKey) Returns a view of the portion of this map whose keys are strictly less than `toKey`. |
| abstract [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<K\> | [keySet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#keySet())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` view of the keys contained in this map. |
| abstract K | [lastKey](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#lastKey())() Returns the last (highest) key currently in this map. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [subMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#subMap(K,%20K))(K fromKey, K toKey) Returns a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive. |
| abstract [SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, V\> | [tailMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#tailMap(K))(K fromKey) Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`. |
| abstract [Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\<V\> | [values](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html#values())() Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` view of the values contained in this map. |

## Public Constructors

#### public
**ConcurrentSkipListMap**
()

Constructs a new, empty map, sorted according to the
{@linkplain Comparable natural ordering} of the keys.

#### public
**ConcurrentSkipListMap**
([Comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html)\<? super K\> comparator)

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

##### Parameters

| comparator | the comparator that will be used to order this map. If `null`, the {@linkplain Comparable natural ordering} of the keys will be used. |
|---|---|

#### public
**ConcurrentSkipListMap**
([Map](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.html)\<? extends K, ? extends V\> m)

Constructs a new map containing the same mappings as the given map,
sorted according to the {@linkplain Comparable natural ordering} of
the keys.

##### Parameters

| m | the map whose mappings are to be placed in this map |
|---|---|

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the keys in `m` are not `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Comparable.html`, or are not mutually comparable |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified map or any of its keys or values are null |
|---|---|

#### public
**ConcurrentSkipListMap**
([SortedMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/SortedMap.html)\<K, ? extends V\> m)

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

##### Parameters

| m | the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map |
|---|---|

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified sorted map or any of its keys or values are null |
|---|---|

## Public Methods

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**ceilingEntry**
(K key)

Returns a key-value mapping associated with the least key
greater than or equal to the given key, or `null` if
there is no such entry. The returned entry does *not*
support the `Entry.setValue` method.

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public K
**ceilingKey**
(K key)

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

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public void
**clear**
()

Removes all of the mappings from this map.

#### public [ConcurrentSkipListMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html)\<K, V\>
**clone**
()

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

##### Returns

- a shallow copy of this map

#### public [Comparator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Comparator.html)\<? super K\>
**comparator**
()

Returns the comparator used to order the keys in this map, or
`null` if this map uses the {@linkplain Comparable
natural ordering} of its keys.

##### Returns

- the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys

#### public V
**compute**
(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction)

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 | key with which the specified value is to be associated |
| remappingFunction | the function to compute a value |
|---|---|

##### Returns

- the new value associated with the specified key, or null if none

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null or the remappingFunction is null |
|---|---|

#### public V
**computeIfAbsent**
(K key, [Function](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Function.html)\<? super K, ? extends V\> mappingFunction)

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 | key with which the specified value is to be associated |
| mappingFunction | the function to compute a value |
|---|---|

##### Returns

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

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null or the mappingFunction is null |
|---|---|

#### public V
**computeIfPresent**
(K key, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> remappingFunction)

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 | key with which a value may be associated |
| remappingFunction | the function to compute a value |
|---|---|

##### Returns

- the new value associated with the specified key, or null if none

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null or the remappingFunction is null |
|---|---|

#### public boolean
**containsKey**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key)

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

##### Parameters

| key | key whose presence in this map is to be tested |
|---|---|

##### Returns

- `true` if this map contains a mapping for the specified key

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public boolean
**containsValue**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value)

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 | value whose presence in this map is to be tested |
|---|---|

##### Returns

- `true` if a mapping to `value` exists; `false` otherwise

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified value is null |
|---|---|

#### public [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\>
**descendingKeySet**
()

Returns a reverse order `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` 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. 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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

##### Returns

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

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**descendingMap**
()

Returns a reverse order view of the mappings contained in this map.
The descending map is backed by this map, so changes to the map are
reflected in the descending map, and vice-versa.

The returned map has an ordering equivalent to
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collections.html#reverseOrder(java.util.Comparator<T>)``(comparator())`.
The expression `m.descendingMap().descendingMap()` returns a
view of `m` essentially equivalent to `m`.

##### Returns

- a reverse order view of this map

#### public [Set](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html)\<[Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>\>
**entrySet**
()

Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Set.html` 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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#CONCURRENT`,
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#NONNULL`, `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#SORTED` and
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

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

##### Returns

- a set view of the mappings contained in this map, sorted in ascending key order

#### public boolean
**equals**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o)

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

| o | object to be compared for equality with this map |
|---|---|

##### Returns

- `true` if the specified object is equal to this map

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**firstEntry**
()

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.

##### Returns

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

#### public K
**firstKey**
()

Returns the first (lowest) key currently in this map.

##### Returns

- the first (lowest) key currently in this map

##### Throws

| [NoSuchElementException](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NoSuchElementException.html) |   |
|---|---|

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**floorEntry**
(K key)

Returns a key-value mapping associated with the greatest key
less than or equal to the given key, or `null` if there
is no such key. The returned entry does *not* support
the `Entry.setValue` method.

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public K
**floorKey**
(K key)

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

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public void
**forEach**
([BiConsumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiConsumer.html)\<? super K, ? super V\> action)

Performs the given action for each entry in this map until all entries
have been processed or the action throws an exception. Unless
otherwise specified by the implementing class, actions are performed in
the order of entry set iteration (if an iteration order is specified.)
Exceptions thrown by the action are relayed to the caller.

##### Parameters

| action | The action to be performed for each entry |
|---|---|

#### public V
**get**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key)

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 | the key whose associated value is to be returned |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public V
**getOrDefault**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, V defaultValue)

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 | the key |
| defaultValue | the value to return if this map contains no mapping for the given key |
|---|---|

##### Returns

- the mapping for the key, if present; else the defaultValue

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**headMap**
(K toKey)

Returns a view of the portion of this map whose keys are
strictly less than `toKey`. The returned map is backed
by this map, so changes in the returned map are reflected in
this map, and vice-versa. The returned map supports all
optional map operations that this map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside its range.

Equivalent to `headMap(toKey, false)`.

##### Parameters

| toKey | high endpoint (exclusive) of the keys in the returned map |
|---|---|

##### Returns

- a view of the portion of this map whose keys are strictly less than `toKey`

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `toKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**headMap**
(K toKey, boolean inclusive)

Returns a view of the portion of this map whose keys are less than (or
equal to, if `inclusive` is true) `toKey`. The returned
map is backed by this map, so changes in the returned map are reflected
in this map, and vice-versa. The returned map supports all optional
map operations that this map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside its range.

##### Parameters

| toKey | high endpoint of the keys in the returned map |
| inclusive | `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 `inclusive` is true) `toKey`

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `toKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**higherEntry**
(K key)

Returns a key-value mapping associated with the least key
strictly greater than the given key, or `null` if there
is no such key. The returned entry does *not* support
the `Entry.setValue` method.

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public K
**higherKey**
(K key)

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

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public boolean
**isEmpty**
()

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

##### Returns

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

#### public [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\>
**keySet**
()

Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` view of the keys contained in this map.

The set's iterator returns the keys in ascending order.
The set's spliterator additionally reports `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#CONCURRENT`,
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#NONNULL`, `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#SORTED` and
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#ORDERED`, with an encounter order that is ascending
key order. The spliterator's comparator (see
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#getComparator()`) is `null` if
the map's comparator (see `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentSkipListMap.html#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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

This method is equivalent to method `navigableKeySet`.

##### Returns

- a navigable set view of the keys in this map

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**lastEntry**
()

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.

##### Returns

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

#### public K
**lastKey**
()

Returns the last (highest) key currently in this map.

##### Returns

- the last (highest) key currently in this map

##### Throws

| [NoSuchElementException](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NoSuchElementException.html) |   |
|---|---|

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<K, V\>
**lowerEntry**
(K key)

Returns a key-value mapping associated with the greatest key
strictly less than the given key, or `null` if there is
no such key. The returned entry does *not* support the
`Entry.setValue` method.

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public K
**lowerKey**
(K key)

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

##### Parameters

| key | the key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public V
**merge**
(K key, V value, [BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super V, ? super V, ? extends V\> remappingFunction)

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 | key with which the specified value is to be associated |
| value | the value to use if absent |
| remappingFunction | the function to recompute a value if present |
|---|---|

##### Returns

- the new value associated with the specified key, or null if none

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key or value is null or the remappingFunction is null |
|---|---|

#### public [NavigableSet](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html)\<K\>
**navigableKeySet**
()

Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/NavigableSet.html` 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. 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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

##### Returns

- a navigable set view of the keys in this map

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<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.
The returned entry does *not* support
the `Entry.setValue` method.

##### Returns

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

#### public [Entry](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Map.Entry.html)\<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.
The returned entry does *not* support
the `Entry.setValue` method.

##### Returns

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

#### public V
**put**
(K key, V value)

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 | key with which the specified value is to be associated |
| value | value to be associated with the specified key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key or value is null |
|---|---|

#### public V
**putIfAbsent**
(K key, V value)

If the specified key is not already associated
with a value, associates it with the given value.
This is equivalent to, for this `map`:

     if (!map.containsKey(key))
       return map.put(key, value);
     else
       return map.get(key);

except that the action is performed atomically.

<br />

##### Parameters

| key | key with which the specified value is to be associated |
| value | value to be associated with the specified key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key or value is null |
|---|---|

#### public boolean
**remove**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key, [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) value)

Removes the entry for a key only if currently mapped to a given value.
This is equivalent to, for this `map`:

     if (map.containsKey(key)
         && Objects.equals(map.get(key), value)) {
       map.remove(key);
       return true;
     } else {
       return false;
     }

except that the action is performed atomically.

<br />

##### Parameters

| key | key with which the specified value is associated |
| value | value expected to be associated with the specified key |
|---|---|

##### Returns

- `true` if the value was removed

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public V
**remove**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) key)

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

##### Parameters

| key | key for which mapping should be removed |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key is null |
|---|---|

#### public boolean
**replace**
(K key, V oldValue, V newValue)

Replaces the entry for a key only if currently mapped to a given value.
This is equivalent to, for this `map`:

     if (map.containsKey(key)
         && Objects.equals(map.get(key), oldValue)) {
       map.put(key, newValue);
       return true;
     } else {
       return false;
     }

except that the action is performed atomically.

<br />

##### Parameters

| key | key with which the specified value is associated |
| oldValue | value expected to be associated with the specified key |
| newValue | value to be associated with the specified key |
|---|---|

##### Returns

- `true` if the value was replaced

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if any of the arguments are null |
|---|---|

#### public V
**replace**
(K key, V value)

Replaces the entry for a key only if currently mapped to some value.
This is equivalent to, for this `map`:

     if (map.containsKey(key))
       return map.put(key, value);
     else
       return null;

except that the action is performed atomically.

<br />

##### Parameters

| key | key with which the specified value is associated |
| value | value to be associated with the specified key |
|---|---|

##### Returns

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

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | if the specified key cannot be compared with the keys currently in the map |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified key or value is null |
|---|---|

#### public void
**replaceAll**
([BiFunction](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/BiFunction.html)\<? super K, ? super V, ? extends V\> function)

Replaces each entry's value with the result of invoking the given
function on that entry until all entries have been processed or the
function throws an exception. Exceptions thrown by the function are
relayed to the caller.

##### Parameters

| function | the function to apply to each entry |
|---|---|

#### public int
**size**
()

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

Beware that, unlike in most collections, this method is
*NOT* a constant-time operation. Because of the
asynchronous nature of these maps, determining the current
number of elements requires traversing them all to count them.
Additionally, it is possible for the size to change during
execution of this method, in which case the returned result
will be inaccurate. Thus, this method is typically not very
useful in concurrent applications.

##### Returns

- the number of elements in this map

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**subMap**
(K fromKey, K toKey)

Returns a view of the portion of this map whose keys range from
`fromKey`, inclusive, to `toKey`, exclusive. (If
`fromKey` and `toKey` are equal, the returned map
is empty.) The returned map is backed by this map, so changes
in the returned map are reflected in this map, and vice-versa.
The returned map supports all optional map operations that this
map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside its range.

Equivalent to `subMap(fromKey, true, toKey, false)`.

##### Parameters

| fromKey | low endpoint (inclusive) of the keys in the returned map |
| toKey | high endpoint (exclusive) of the keys in the returned map |
|---|---|

##### Returns

- a view of the portion of this map whose keys range from `fromKey`, inclusive, to `toKey`, exclusive

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `fromKey` or `toKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**subMap**
(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)

Returns a view of the portion of this map whose keys range from
`fromKey` to `toKey`. If `fromKey` and
`toKey` are equal, the returned map is empty unless
`fromInclusive` and `toInclusive` are both true. The
returned map is backed by this map, so changes in the returned map are
reflected in this map, and vice-versa. The returned map supports all
optional map operations that this map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside of its range, or to construct a
submap either of whose endpoints lie outside its range.

##### Parameters

| fromKey | low endpoint of the keys in the returned map |
| fromInclusive | `true` if the low endpoint is to be included in the returned view |
| toKey | high endpoint of the keys in the returned map |
| toInclusive | `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 `fromKey` to `toKey`

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `fromKey` or `toKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**tailMap**
(K fromKey, boolean inclusive)

Returns a view of the portion of this map whose keys are greater than (or
equal to, if `inclusive` is true) `fromKey`. The returned
map is backed by this map, so changes in the returned map are reflected
in this map, and vice-versa. The returned map supports all optional
map operations that this map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside its range.

##### Parameters

| fromKey | low endpoint of the keys in the returned map |
| inclusive | `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 `inclusive` is true) `fromKey`

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `fromKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [ConcurrentNavigableMap](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/ConcurrentNavigableMap.html)\<K, V\>
**tailMap**
(K fromKey)

Returns a view of the portion of this map whose keys are
greater than or equal to `fromKey`. The returned map is
backed by this map, so changes in the returned map are
reflected in this map, and vice-versa. The returned map
supports all optional map operations that this map supports.

The returned map will throw an `IllegalArgumentException`
on an attempt to insert a key outside its range.

Equivalent to `tailMap(fromKey, true)`.

##### Parameters

| fromKey | low endpoint (inclusive) of the keys in the returned map |
|---|---|

##### Returns

- a view of the portion of this map whose keys are greater than or equal to `fromKey`

##### Throws

| [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) |   |
| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `fromKey` is null |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) |   |
|---|---|

#### public [Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\<V\>
**values**
()

Returns a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` 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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#CONCURRENT`, `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#NONNULL` and
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html#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*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly).

##### Returns

- a collection view of the values contained in this map