java.util
Class TreeMap<K,V>

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

Type Parameters: All Implemented Interfaces:

K - the type of keys maintained by this map

V - the type of mapped values Serializable , Cloneable , Map <K,V>, SortedMap <K,V>

All Implemented Interfaces:

Serializable , Cloneable , Map <K,V>, NavigableMap <K,V>, SortedMap <K,V>

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

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. Red-Black tree based implementation of the SortedMap interface. This class guarantees that the map will be in ascending key order, sorted according to the natural order for the key's class (see Comparable ), or by the comparator provided at 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 sorted map (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 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 Collections.synchronizedMap method. This is best done at creation time, to prevent accidental unsynchronized access to the map:

 SortedMap Map m = Collections.synchronizedSortedMap(new Collections.synchronizedMap(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 or ConcurrentModificationException add 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 methods, the iterator throws a Map.Entry ConcurrentModificationException 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 . 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 Entry.setValue ConcurrentModificationException method. (Note however that it is possible to change mappings in the associated map using put .) 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.

This class is a member of the Java Collections Framework .

Since:

1.2

See Also:

Map , HashMap , Hashtable , Comparable , Comparator , Collection , Collections.synchronizedMap(Map) , Serialized Form

Nested Class Summary

 

Nested classes/interfaces inherited from class java.util. AbstractMap
AbstractMap.SimpleEntry < K , V >, AbstractMap.SimpleImmutableEntry < K , V

 

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

 

Method Summary
Map.Entry < K , V	ceilingEntry ( K           Returns a key-value mapping associated with the least key greater than or equal to the given key, or null if there is no such key.
void	clear ()           Removes all mappings from this TreeMap.
K	ceilingKey ( K           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 its keys' natural order.
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.
Set < Map.Entry < K , V	descendingEntrySet entrySet ()           Returns a Set set view of the mappings contained in this map.
Set < K	descendingKeySet firstKey ()           Returns a Set the first (lowest) key currently in this sorted map.
Set < Map.Entry < K , V	entrySet ()           Returns a Set
V	get ( Object           Returns the value to which this map maps the specified key.
Map.Entry SortedMap < K , V	firstEntry headMap () ( K           Returns a key-value mapping associated with view of the least key in portion of this map, or map whose keys are strictly less than null toKey if the map is empty. .
Set < K	firstKey keySet ()           Returns a Set view of the first (lowest) key currently keys contained in this map.
Map.Entry < K , V	floorEntry ( K           Returns a key-value mapping associated with the greatest key less than or equal to the given key, or null if there is no such key.
K	lastKey ()           Returns the last (highest) key currently in this sorted map.
K	floorKey ( K           Returns the greatest key less than or equal to the given key, or null if there is no such key.
V	get ( Object           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           Equivalent to navigableHeadMap(K) SortedMap interface.
Map.Entry < K , V	higherEntry ( K           Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.
K	higherKey ( K           Returns the least key strictly greater than the given key, or null if there is no such key.
Set < K	keySet ()           Returns a Set
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.
Map.Entry < K , V	lowerEntry ( K           Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.
K	lowerKey ( K           Returns the greatest key strictly less than the given key, or null if there is no such key.
NavigableMap < K , V	navigableHeadMap ( K           Returns a view of the portion of this map whose keys are strictly less than toKey .
NavigableMap < K , V	navigableSubMap ( K  fromKey, K           Returns a view of the portion of this map whose keys range from fromKey , inclusive, to toKey , exclusive.
NavigableMap < K , V	navigableTailMap ( K           Returns a view of the portion of this map whose keys are greater than or equal to fromKey .
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.
Map.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.
int	size ()           Returns the number of key-value mappings in this map.
SortedMap < K , V	subMap ( K  fromKey, K           Equivalent           Returns a view of the portion of this map whose keys range from fromKey , inclusive, to navigableSubMap(K, K) SortedMap toKey interface. , exclusive.
SortedMap < K , V	tailMap ( K           Equivalent           Returns a view of the portion of this map whose keys are greater than or equal to navigableTailMap(K) SortedMap fromKey interface. .
Collection < V	values ()           Returns a Collection collection view of the values contained in this map.

 

Methods inherited from class java.util. AbstractMap
equals , hashCode , isEmpty , toString

 

Methods inherited from class java.lang. Object
finalize , getClass , notify , notifyAll , wait , wait , wait

 

Methods inherited from interface java.util. Map
equals , hashCode , isEmpty

 

Constructor Detail

TreeMap

public TreeMap()

Constructs a new, empty tree map, using sorted according to the keys' natural ordering of its keys. order. All keys inserted into the map must implement the Comparable Comparable interface. Furthermore, all such keys must be mutually comparable : k1.compareTo(k2) must not throw a ClassCastException for any elements 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 .

See Also:

Comparable

TreeMap

public TreeMap(Comparator<? super K> comparator) > c) 

Constructs a new, empty tree map, ordered sorted 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 c - the comparator that will be used to order sort this map. If A null , the natural ordering of the keys will be used. value indicates that the keys' natural ordering should be used.

TreeMap

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

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

Parameters:

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

Throws:

ClassCastException - if the keys in m t are not Comparable , Comparable, or are not mutually comparable comparable.

NullPointerException - if the specified map is null null.

TreeMap

public TreeMap(SortedMap<K,? extends V> m)

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

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 map.

Throws:

NullPointerException - if the specified sorted map is null null.

size

public int size()

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

Specified by:

size in interface Map < K , V >

Overrides:

size in class AbstractMap < K , V >

Returns:

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

containsKey

public boolean containsKey(Object key)

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

Specified by:

containsKey in interface Map < K , V >

Overrides:

containsKey in class AbstractMap < K , V >

Parameters:

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

Returns:

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

Throws:

ClassCastException - if the specified key cannot be compared with the keys currently in the map map.

NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit tolerate null keys keys.

containsValue

public 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 Map size for most implementations. implementations of Map.

Specified by:

containsValue in interface Map < K , V >

Overrides:

containsValue in class AbstractMap < K , V >

Parameters:

value - value whose presence in this map Map is to be tested tested.

Returns:

true if a mapping to value exists; false otherwise otherwise.

Since:

1.2

get

public 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 Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key. 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. null . The containsKey containsKey operation may be used to distinguish these two cases.

Specified by:

get in interface Map < K , V >

Overrides:

get in class AbstractMap < K , V >

Parameters:

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

Returns:

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

Throws:

ClassCastException - if the specified key cannot be compared with the keys currently in the map map.

NullPointerException - if the specified key is null and this map uses natural ordering, or its comparator does not permit tolerate null keys keys.

See Also:

containsKey(Object)

comparator

public Comparator<? super K> comparator()

Description copied from interface: SortedMap

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

Specified by:

comparator in interface SortedMap < K , V >

Returns:

the comparator used to order the keys in associated with this sorted map, or null if this map uses the natural ordering of its keys if it uses its keys' natural sort method.

firstKey

public K firstKey()

Description copied from interface: SortedMap

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

Specified by:

firstKey in interface SortedMap < K , V >

Returns:

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

Throws:

NoSuchElementException - if this map is empty - Map is empty.

lastKey

public K lastKey()

Description copied from interface: SortedMap

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

Specified by:

lastKey in interface SortedMap < K , V >

Returns:

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

Throws:

NoSuchElementException - if this map is empty - Map is empty.

putAll

public 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.

Specified by:

putAll in interface Map < K , V >

Overrides:

putAll in class AbstractMap < K , V >

Parameters:

map - mappings to be stored in this map map.

Throws:

ClassCastException - if the class of a key or value in the specified map prevents it from being stored in this map map.

NullPointerException - if the specified given map is null or the specified map contains a null key and this map does not permit null keys and a key in the specified map is null .

put

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 this key, the old value is replaced.

Specified by:

put in interface Map < K , V >

Overrides:

put in class AbstractMap < K , V >

Parameters:

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

value - value to be associated with the specified key key.

Returns:

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

Throws:

ClassCastException - if the specified key cannot be compared with the keys currently in the map map.

NullPointerException - if the specified key is null and this map uses natural ordering, order, or its comparator does not permit tolerate null keys keys.

remove

public V remove(Object key)

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

Specified by:

remove in interface Map < K , V >

Overrides:

remove in class AbstractMap < K , V >

Parameters:

key - key for which mapping should be removed

Returns:

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

Throws:

ClassCastException - if the specified key cannot be compared with the keys currently in the map map.

NullPointerException - if the specified key is null and this map uses natural ordering, order, or its comparator does not permit tolerate null keys keys.

clear

public void clear()

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

Specified by:

clear in interface Map < K , V >

Overrides:

clear in class AbstractMap < K , V >

clone

public Object clone()

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

Overrides:

clone in class AbstractMap < K , V >

Returns:

a shallow copy of this map Map.

See Also:

Cloneable

firstEntry

 
public Map.Entry< K, V> firstEntry () 

Description copied from interface: NavigableMap

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

Specified by:

firstEntry in interface NavigableMap < K , V >

Returns:

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

Since:

1.6

lastEntry

 
public Map.Entry< K, V> lastEntry () 

Description copied from interface: NavigableMap

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

Specified by:

lastEntry in interface NavigableMap < K , V >

Returns:

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

Since:

1.6

pollFirstEntry

 
public Map.Entry< K, V> pollFirstEntry () 

Description copied from interface: NavigableMap

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

Specified by:

pollFirstEntry in interface NavigableMap < K , V >

Returns:

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

Since:

1.6

pollLastEntry

 
public Map.Entry< K, V> pollLastEntry () 

Description copied from interface: NavigableMap

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

Specified by:

pollLastEntry in interface NavigableMap < K , V >

Returns:

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

Since:

1.6

lowerEntry

 
public Map.Entry< K, V> lowerEntry ( K key) 

Description copied from interface: NavigableMap

Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.

Specified by:

lowerEntry in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

lowerKey

 
public KlowerKey ( K key) 

Description copied from interface: NavigableMap

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

Specified by:

lowerKey in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

floorEntry

 
public Map.Entry< K, V> floorEntry ( K key) 

Description copied from interface: NavigableMap

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.

Specified by:

floorEntry in interface NavigableMap < K , V >

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 - 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

Since:

1.6

floorKey

 
public KfloorKey ( K key) 

Description copied from interface: NavigableMap

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

Specified by:

floorKey in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

ceilingEntry

 
public Map.Entry< K, V> ceilingEntry ( K key) 

Description copied from interface: NavigableMap

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.

Specified by:

ceilingEntry in interface NavigableMap < K , V >

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 - 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

Since:

1.6

ceilingKey

 
public KceilingKey ( K key) 

Description copied from interface: NavigableMap

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

Specified by:

ceilingKey in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

higherEntry

 
public Map.Entry< K, V> higherEntry ( K key) 

Description copied from interface: NavigableMap

Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.

Specified by:

higherEntry in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

higherKey

 
public KhigherKey ( K key) 

Description copied from interface: NavigableMap

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

Specified by:

higherKey in interface NavigableMap < K , V >

Parameters:

key - the key

Returns:

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

Since:

1.6

keySet

public Set<K> keySet()

Returns a Set Set view of the keys contained in this map. The set's iterator returns will return the keys in ascending order. The set map 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 this remove TreeMap operation), instance, so changes to this map are reflected in the results of the iteration are undefined. Set, and vice-versa. The set 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.

Specified by:

keySet in interface Map < K , V >

Specified by:

keySet in interface SortedMap < K , V >

Overrides:

keySet in class AbstractMap < K , V >

Returns:

a set view of the keys contained in this map TreeMap.

values

public 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 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 Returns a collection view of the values contained in this map. The collection's iterator will return the values in the order that their corresponding keys appear in the tree. The collection is backed by this remove TreeMap operation), instance, so changes to this map are reflected in the results of the iteration are undefined. collection, and vice-versa. The collection supports element removal, which removes the corresponding mapping from the map, via map through the Iterator.remove , Collection.remove , removeAll , retainAll , and clear operations. It does not support the add or addAll operations.

Specified by:

values in interface Map < K , V >

Specified by:

values in interface SortedMap < K , V >

Overrides:

values in class AbstractMap < K , V >

Returns:

a collection view of the values contained in this map map.

entrySet

public Set<Map.Entry<K,V>> entrySet()

Returns a Set set view of the mappings contained in this map. The set's iterator returns the entries mappings in ascending key order. The set is backed by the map, so changes to the map are reflected Each element in the set, and vice-versa. If the map is modified while an iteration over the returned set is in progress (except through the iterator's own a remove Map.Entry operation, or through the . The set is backed by this map, so changes to this map are reflected in the set, and vice-versa. The set supports element removal, which removes the corresponding mapping from the TreeMap, 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.

Specified by:

entrySet in interface Map < K , V >

Specified by:

entrySet in interface SortedMap < K , V >

Specified by:

entrySet in class AbstractMap < K , V >

Returns:

a set view of the mappings contained in this map map.

See Also:

Map.Entry

descendingEntrySet

 
public Set< Map.Entry< K, V>> descendingEntrySet () 

Description copied from interface: NavigableMap

Returns a Set view of the mappings contained in this map. The set's iterator returns the entries in descending 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.

Specified by:

descendingEntrySet in interface NavigableMap < K , V >

Returns:

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

Since:

1.6

descendingKeySet

 
public Set< K> descendingKeySet () 

Description copied from interface: NavigableMap

Returns a Set 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.

Specified by:

descendingKeySet in interface NavigableMap < K , V >

Returns:

a set view of the keys contained in this map, sorted in descending order

Since:

1.6

navigableSubMap

 
public NavigableMap< K, V> navigableSubMap ( K fromKey,
 K toKey) 

Description copied from interface: NavigableMap

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.

Specified by:

navigableSubMap in interface NavigableMap < K , V >

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 - if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.

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

IllegalArgumentException - if fromKey is greater than toKey ; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range

Since:

1.6