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Added in API level 1

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
From class java.lang.Object
From interface java.util.Map
From interface java.util.NavigableMap
From interface java.util.SortedMap

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
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