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Added in API level 1

Summary: Ctors | Methods | Inherited Methods | [Expand All]

TreeMap

public class TreeMap
extends AbstractMap<K, V> implements NavigableMap<K, V>, Cloneable, Serializable

java.lang.Object
↳	java.util.AbstractMap<K, V>
	↳	java.util.TreeMap<K, V>

A Red-Black tree based NavigableMap implementation. The map is sorted according to the natural ordering of its keys, or by a Comparator provided at map creation time, depending on which constructor is used.

This implementation provides guaranteed log(n) time cost for the containsKey, get, put and remove operations. Algorithms are adaptations of those in Cormen, Leiserson, and Rivest's Introduction to Algorithms.

Note that the ordering maintained by a tree map, like any sorted map, and whether or not an explicit comparator is provided, must be consistent with equals if this sorted map is to correctly implement the Map interface. (See Comparable or Comparator for a precise definition of consistent with equals.) This is so because the Map interface is defined in terms of the equals operation, but a sorted map performs all key comparisons using its compareTo (or compare) method, so two keys that are deemed equal by this method are, from the standpoint of the sorted map, equal. The behavior of a sorted map is well-defined even if its ordering is inconsistent with equals; it just fails to obey the general contract of the Map interface.

Note that this implementation is not synchronized. If multiple threads access a map concurrently, and at least one of the threads modifies the map structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more mappings; merely changing the value associated with an existing key is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the map. If no such object exists, the map should be "wrapped" using the Collections.synchronizedSortedMap method. This is best done at creation time, to prevent accidental unsynchronized access to the map:

   SortedMap m = Collections.synchronizedSortedMap(new TreeMap(...));

The iterators returned by the iterator method of the collections returned by all of this class's "collection view methods" are fail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove method, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.

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.)

This class is a member of the Java Collections Framework.

See also:

Summary

Public constructors
`TreeMap()` Constructs a new, empty tree map, using the natural ordering of its keys.
`TreeMap(Comparator<? super K> comparator)` Constructs a new, empty tree map, ordered according to the given comparator.
`TreeMap(Map<? extends K, ? extends V> m)` Constructs a new tree map containing the same mappings as the given map, ordered according to the natural ordering of its keys.
`TreeMap(SortedMap<K, ? extends V> m)` Constructs a new tree map containing the same mappings and using the same ordering as the specified sorted map.

Public methods
`Entry<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 key.
`K`	`ceilingKey(K key)` Returns the least key greater than or equal to the given key, or `null` if there is no such key.
`void`	`clear()` Removes all of the mappings from this map.
`Object`	`clone()` Returns a shallow copy of this `TreeMap` instance.
`Comparator<? super K>`	`comparator()` Returns the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys.
`boolean`	`containsKey(Object key)` Returns `true` if this map contains a mapping for the specified key.
`boolean`	`containsValue(Object value)` Returns `true` if this map maps one or more keys to the specified value.
`NavigableSet<K>`	`descendingKeySet()` Returns a reverse order `NavigableSet` view of the keys contained in this map.
`NavigableMap<K, V>`	`descendingMap()` Returns a reverse order view of the mappings contained in this map.
`Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`Entry<K, V>`	`firstEntry()` Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
`K`	`firstKey()` Returns the first (lowest) key currently in this map.
`Entry<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.
`K`	`floorKey(K key)` Returns the greatest key less than or equal to the given key, or `null` if there is no such key.
`void`	`forEach(BiConsumer<? 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(Object key)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
`SortedMap<K, V>`	`headMap(K toKey)` Returns a view of the portion of this map whose keys are strictly less than `toKey`. Equivalent to `headMap(toKey, false)`.
`NavigableMap<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`.
`Entry<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.
`K`	`higherKey(K key)` Returns the least key strictly greater than the given key, or `null` if there is no such key.
`Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`Entry<K, V>`	`lastEntry()` Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
`K`	`lastKey()` Returns the last (highest) key currently in this map.
`Entry<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.
`K`	`lowerKey(K key)` Returns the greatest key strictly less than the given key, or `null` if there is no such key.
`NavigableSet<K>`	`navigableKeySet()` Returns a `NavigableSet` view of the keys contained in this map.
`Entry<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.
`Entry<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.
`V`	`put(K key, V value)` Associates the specified value with the specified key in this map.
`void`	`putAll(Map<? extends K, ? extends V> map)` Copies all of the mappings from the specified map to this map.
`V`	`remove(Object key)` Removes the mapping for this key from this TreeMap if present.
`boolean`	`replace(K key, V oldValue, V newValue)` Replaces the entry for the specified key only if currently mapped to the specified value.
`V`	`replace(K key, V value)` Replaces the entry for the specified key only if it is currently mapped to some value.
`void`	`replaceAll(BiFunction<? 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()` Returns the number of key-value mappings in this map.
`SortedMap<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. Equivalent to `subMap(fromKey, true, toKey, false)`.
`NavigableMap<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`.
`NavigableMap<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`.
`SortedMap<K, V>`	`tailMap(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<V>`	`values()` Returns a `Collection` view of the values contained in this map.

Inherited methods

From class


  
    java.util.AbstractMap

`void`	`clear()` Removes all of the mappings from this map (optional operation). This implementation calls `entrySet().clear()`.
`Object`	`clone()` Returns a shallow copy of this `AbstractMap` instance: the keys and values themselves are not cloned.
`boolean`	`containsKey(Object key)` Returns `true` if this map contains a mapping for the specified key. This implementation iterates over `entrySet()` searching for an entry with the specified key.
`boolean`	`containsValue(Object value)` Returns `true` if this map maps one or more keys to the specified value. This implementation iterates over `entrySet()` searching for an entry with the specified value.
`abstract Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`V`	`get(Object key)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key. This implementation iterates over `entrySet()` searching for an entry with the specified key.
`int`	`hashCode()` Returns the hash code value for this map.
`boolean`	`isEmpty()` Returns `true` if this map contains no key-value mappings. This implementation returns `size() == 0`.
`Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map. This implementation returns a set that subclasses `AbstractSet`.
`V`	`put(K key, V value)` Associates the specified value with the specified key in this map (optional operation). This implementation always throws an `UnsupportedOperationException`.
`void`	`putAll(Map<? extends K, ? extends V> m)` Copies all of the mappings from the specified map to this map (optional operation). This implementation iterates over the specified map's `entrySet()` collection, and calls this map's `put` operation once for each entry returned by the iteration.
`V`	`remove(Object key)` Removes the mapping for a key from this map if it is present (optional operation). This implementation iterates over `entrySet()` searching for an entry with the specified key.
`int`	`size()` Returns the number of key-value mappings in this map. This implementation returns `entrySet().size()`.
`String`	`toString()` Returns a string representation of this map.
`Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map. This implementation returns a collection that subclasses `AbstractCollection`.

From class


  
    java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long millis, int nanos)` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
`final void`	`wait(long millis)` Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.
`final void`	`wait()` Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.

From interface


  
    java.util.Map

`abstract void`	`clear()` Removes all of the mappings from this map (optional operation).
`default V`	`compute(K key, BiFunction<? 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).
`default V`	`computeIfAbsent(K key, Function<? 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`.
`default V`	`computeIfPresent(K key, BiFunction<? 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(Object key)` Returns `true` if this map contains a mapping for the specified key.
`abstract boolean`	`containsValue(Object value)` Returns `true` if this map maps one or more keys to the specified value.
`abstract Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`abstract boolean`	`equals(Object o)` Compares the specified object with this map for equality.
`default void`	`forEach(BiConsumer<? 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(Object key)` Returns the value to which the specified key is mapped, or `null` if this map contains no mapping for the key.
`default V`	`getOrDefault(Object 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()` Returns the hash code value for this map.
`abstract boolean`	`isEmpty()` Returns `true` if this map contains no key-value mappings.
`abstract Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`default V`	`merge(K key, V value, BiFunction<? 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(K key, V value)` Associates the specified value with the specified key in this map (optional operation).
`abstract void`	`putAll(Map<? extends K, ? extends V> m)` Copies all of the mappings from the specified map to this map (optional operation).
`default V`	`putIfAbsent(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.
`default boolean`	`remove(Object key, Object value)` Removes the entry for the specified key only if it is currently mapped to the specified value.
`abstract V`	`remove(Object key)` Removes the mapping for a key from this map if it is present (optional operation).
`default boolean`	`replace(K key, V oldValue, V newValue)` Replaces the entry for the specified key only if currently mapped to the specified value.
`default V`	`replace(K key, V value)` Replaces the entry for the specified key only if it is currently mapped to some value.
`default void`	`replaceAll(BiFunction<? 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()` Returns the number of key-value mappings in this map.
`abstract Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map.

From interface


  
    java.util.NavigableMap

`abstract Entry<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 key.
`abstract K`	`ceilingKey(K key)` Returns the least key greater than or equal to the given key, or `null` if there is no such key.
`abstract NavigableSet<K>`	`descendingKeySet()` Returns a reverse order `NavigableSet` view of the keys contained in this map.
`abstract NavigableMap<K, V>`	`descendingMap()` Returns a reverse order view of the mappings contained in this map.
`abstract Entry<K, V>`	`firstEntry()` Returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
`abstract Entry<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.
`abstract K`	`floorKey(K key)` Returns the greatest key less than or equal to the given key, or `null` if there is no such key.
`abstract SortedMap<K, V>`	`headMap(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<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`.
`abstract Entry<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.
`abstract K`	`higherKey(K key)` Returns the least key strictly greater than the given key, or `null` if there is no such key.
`abstract Entry<K, V>`	`lastEntry()` Returns a key-value mapping associated with the greatest key in this map, or `null` if the map is empty.
`abstract Entry<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.
`abstract K`	`lowerKey(K key)` Returns the greatest key strictly less than the given key, or `null` if there is no such key.
`abstract NavigableSet<K>`	`navigableKeySet()` Returns a `NavigableSet` view of the keys contained in this map.
`abstract Entry<K, V>`	`pollFirstEntry()` Removes and returns a key-value mapping associated with the least key in this map, or `null` if the map is empty.
`abstract Entry<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.
`abstract SortedMap<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. Equivalent to `subMap(fromKey, true, toKey, false)`.
`abstract NavigableMap<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`.
`abstract NavigableMap<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`.
`abstract SortedMap<K, V>`	`tailMap(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

`abstract Comparator<? super K>`	`comparator()` Returns the comparator used to order the keys in this map, or `null` if this map uses the natural ordering of its keys.
`abstract Set<Entry<K, V>>`	`entrySet()` Returns a `Set` view of the mappings contained in this map.
`abstract K`	`firstKey()` Returns the first (lowest) key currently in this map.
`abstract SortedMap<K, V>`	`headMap(K toKey)` Returns a view of the portion of this map whose keys are strictly less than `toKey`.
`abstract Set<K>`	`keySet()` Returns a `Set` view of the keys contained in this map.
`abstract K`	`lastKey()` Returns the last (highest) key currently in this map.
`abstract SortedMap<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.
`abstract SortedMap<K, V>`	`tailMap(K fromKey)` Returns a view of the portion of this map whose keys are greater than or equal to `fromKey`.
`abstract Collection<V>`	`values()` Returns a `Collection` view of the values contained in this map.

Public constructors

TreeMap

Added in API level 1

TreeMap ()

Constructs a new, empty tree map, using the natural ordering of its keys. All keys inserted into the map must implement the Comparable interface. Furthermore, all such keys must be mutually comparable: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and k2 in the map. If the user attempts to put a key into the map that violates this constraint (for example, the user attempts to put a string key into a map whose keys are integers), the put(Object key, Object value) call will throw a ClassCastException.

TreeMap

Added in API level 1

TreeMap (Comparator<? super K> comparator)

Constructs a new, empty tree map, ordered according to the given comparator. All keys inserted into the map must be mutually comparable by the given comparator: comparator.compare(k1, k2) must not throw a ClassCastException for any keys k1 and k2 in the map. If the user attempts to put a key into the map that violates this constraint, the put(Object key, Object value) call will throw a ClassCastException.

Parameters
`comparator`	`Comparator`: the comparator that will be used to order this map. If `null`, the natural ordering of the keys will be used.

TreeMap

Added in API level 1

TreeMap (Map<? extends K, ? extends V> m)

Constructs a new tree map containing the same mappings as the given map, ordered according to the natural ordering of its keys. All keys inserted into the new map must implement the Comparable interface. Furthermore, all such keys must be mutually comparable: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and k2 in the map. This method runs in n*log(n) time.

Parameters
`m`	`Map`: the map whose mappings are to be placed in this map

Throws
`ClassCastException`	if the keys in m are not `Comparable`, or are not mutually comparable
`NullPointerException`	if the specified map is null

TreeMap

Added in API level 1

TreeMap (SortedMap<K, ? extends V> m)

Constructs a new tree map containing the same mappings and using the same ordering as the specified sorted map. This method runs in linear time.

Parameters
`m`	`SortedMap`: 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`	if the specified map is null

Public methods

ceilingEntry

Added in API level 9

Entry<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 key.

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

ceilingKey

Added in API level 9

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`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

clear

Added in API level 1

void clear ()

Removes all of the mappings from this map. The map will be empty after this call returns.

clone

Added in API level 1

Object clone ()

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

Returns
`Object`	a shallow copy of this map

comparator

Added in API level 1

Comparator<? super K> comparator ()

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

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

containsKey

Added in API level 1

boolean containsKey (Object key)

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

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

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

Throws
`ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

containsValue

Added in API level 1

boolean containsValue (Object value)

Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that (value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations.

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

Returns
`boolean`	`true` if a mapping to `value` exists; `false` otherwise

descendingKeySet

Added in API level 9

NavigableSet<K> descendingKeySet ()

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

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

descendingMap

Added in API level 9

NavigableMap<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. If either map is modified while an iteration over a collection view of either map is in progress (except through the iterator's own remove operation), the results of the iteration are undefined.

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

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

entrySet

Added in API level 1

Set<Entry<K, V>> entrySet ()

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

The set's iterator returns the entries in ascending key order. The sets's spliterator is late-binding, fail-fast, and additionally reports SORTED and 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. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation, or through the setValue operation on a map entry returned by the iterator) the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Returns
`Set<Entry<K, V>>`	a set view of the mappings contained in this map

firstEntry

Added in API level 9

Entry<K, V> firstEntry ()

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

Returns
`Entry<K, V>`	an entry with the least key, or `null` if this map is empty

firstKey

Added in API level 1

K firstKey ()

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

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

Throws
`NoSuchElementException`

floorEntry

Added in API level 9

Entry<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.

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

floorKey

Added in API level 9

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`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

forEach

Added in API level 24

void forEach (BiConsumer<? 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`	`BiConsumer`: The action to be performed for each entry

get

Added in API level 1

V get (Object 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.)

A return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

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

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

Throws
`ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

headMap

Added in API level 1

SortedMap<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`	`K`: high endpoint (exclusive) of the keys in the returned map

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

Throws
`ClassCastException`
`NullPointerException`	if `toKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

headMap

Added in API level 9

NavigableMap<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`	`K`: high endpoint of the keys in the returned map
`inclusive`	`boolean`: `true` if the high endpoint is to be included in the returned view

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

Throws
`ClassCastException`
`NullPointerException`	if `toKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

higherEntry

Added in API level 9

Entry<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.

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

higherKey

Added in API level 9

K higherKey (K key)

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

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

keySet

Added in API level 1

Set<K> keySet ()

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

The set's iterator returns the keys in ascending order. The set's spliterator is late-binding, fail-fast, and additionally reports SORTED and ORDERED with an encounter order that is ascending key order. The spliterator's comparator (see getComparator()) is null if the tree map's comparator (see comparator()) is null. Otherwise, the spliterator's comparator is the same as or imposes the same total ordering as the tree map's comparator.

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

Returns
`Set<K>`	a set view of the keys contained in this map

lastEntry

Added in API level 9

Entry<K, V> lastEntry ()

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

Returns
`Entry<K, V>`	an entry with the greatest key, or `null` if this map is empty

lastKey

Added in API level 1

K lastKey ()

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

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

Throws
`NoSuchElementException`

lowerEntry

Added in API level 9

Entry<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.

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

lowerKey

Added in API level 9

K lowerKey (K key)

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

Parameters
`key`	`K`: the key

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

Throws
`ClassCastException`
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

navigableKeySet

Added in API level 9

NavigableSet<K> navigableKeySet ()

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

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

pollFirstEntry

Added in API level 9

Entry<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.

Returns
`Entry<K, V>`	the removed first entry of this map, or `null` if this map is empty

pollLastEntry

Added in API level 9

Entry<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.

Returns
`Entry<K, V>`	the removed last entry of this map, or `null` if this map is empty

put

Added in API level 1

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

Returns
`V`	the previous value associated with `key`, or `null` if there was no mapping for `key`. (A `null` return can also indicate that the map previously associated `null` with `key`.)

Throws
`ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

putAll

Added in API level 1

void putAll (Map<? extends K, ? extends V> map)

Copies all of the mappings from the specified map to this map. These mappings replace any mappings that this map had for any of the keys currently in the specified map.

Parameters
`map`	`Map`: mappings to be stored in this map

Throws
`ClassCastException`	if the class of a key or value in the specified map prevents it from being stored in this map
`NullPointerException`	if the specified map is null or the specified map contains a null key and this map does not permit null keys

remove

Added in API level 1

V remove (Object key)

Removes the mapping for this key from this TreeMap if present.

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

Returns
`V`	the previous value associated with `key`, or `null` if there was no mapping for `key`. (A `null` return can also indicate that the map previously associated `null` with `key`.)

Throws
`ClassCastException`	if the specified key cannot be compared with the keys currently in the map
`NullPointerException`	if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys

replace

Added in API level 24

boolean replace (K key, 
                V oldValue, 
                V newValue)

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

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

Returns
`boolean`	`true` if the value was replaced

replace

Added in API level 24

V replace (K key, 
                V value)

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

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

Returns
`V`	the previous value associated with the specified key, or `null` if there was no mapping for the key. (A `null` return can also indicate that the map previously associated `null` with the key, if the implementation supports null values.)

replaceAll

Added in API level 24

void replaceAll (BiFunction<? 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`	`BiFunction`: the function to apply to each entry

size

Added in API level 1

int size ()

Returns the number of key-value mappings in this map.

Returns
`int`	the number of key-value mappings in this map

subMap

Added in API level 1

SortedMap<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`	`K`: low endpoint (inclusive) of the keys in the returned map
`toKey`	`K`: high endpoint (exclusive) of the keys in the returned map

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

Throws
`ClassCastException`
`NullPointerException`	if `fromKey` or `toKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

subMap

Added in API level 9

NavigableMap<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`	`K`: low endpoint of the keys in the returned map
`fromInclusive`	`boolean`: `true` if the low endpoint is to be included in the returned view
`toKey`	`K`: high endpoint of the keys in the returned map
`toInclusive`	`boolean`: `true` if the high endpoint is to be included in the returned view

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

Throws
`ClassCastException`
`NullPointerException`	if `fromKey` or `toKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

tailMap

Added in API level 9

NavigableMap<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`	`K`: low endpoint of the keys in the returned map
`inclusive`	`boolean`: `true` if the low endpoint is to be included in the returned view

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

Throws
`ClassCastException`
`NullPointerException`	if `fromKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

tailMap

Added in API level 1

SortedMap<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`	`K`: low endpoint (inclusive) of the keys in the returned map

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

Throws
`ClassCastException`
`NullPointerException`	if `fromKey` is null and this map uses natural ordering, or its comparator does not permit null keys
`IllegalArgumentException`

values

Added in API level 1

Collection<V> values ()

Returns a Collection view of the values contained in this map.

The collection's iterator returns the values in ascending order of the corresponding keys. The collection's spliterator is late-binding, fail-fast, and additionally reports 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. If the map is modified while an iteration over the collection is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

Returns
`Collection<V>`	a collection view of the values contained in this map