- java.lang.Object
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- java.util.AbstractMap<K,V>
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- java.util.TreeMap<K,V>
 
 
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- Type Parameters:
- K- the type of keys maintained by this map
- V- the type of mapped values
 - All Implemented Interfaces:
- Serializable,- Cloneable,- Map<K,V>,- NavigableMap<K,V>,- SortedMap<K,V>
 
 public class TreeMap<K,V> extends AbstractMap<K,V> implements NavigableMap<K,V>, Cloneable, Serializable A Red-Black tree basedNavigableMapimplementation. The map is sorted according to the natural ordering of its keys, or by aComparatorprovided at map creation time, depending on which constructor is used.This implementation provides guaranteed log(n) time cost for the containsKey,get,putandremoveoperations. 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 equalsif this sorted map is to correctly implement theMapinterface. (SeeComparableorComparatorfor a precise definition of consistent with equals.) This is so because theMapinterface is defined in terms of theequalsoperation, but a sorted map performs all key comparisons using itscompareTo(orcompare) 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 withequals; it just fails to obey the general contract of theMapinterface.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.synchronizedSortedMapmethod. 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 iteratormethod 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 ownremovemethod, the iterator will throw aConcurrentModificationException. 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 ConcurrentModificationExceptionon 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.Entrypairs returned by methods in this class and its views represent snapshots of mappings at the time they were produced. They do not support theEntry.setValuemethod. (Note however that it is possible to change mappings in the associated map usingput.)This class is a member of the Java Collections Framework. - Since:
- 1.2
- See Also:
- Map,- HashMap,- Hashtable,- Comparable,- Comparator,- Collection, Serialized Form
 
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Nested Class Summary- 
Nested classes/interfaces declared in class java.util.AbstractMapAbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
 
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Constructor SummaryConstructors Constructor Description 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.
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Method SummaryAll Methods Instance Methods Concrete Methods Modifier and Type Method Description Map.Entry<K,V>ceilingEntry(K key)Returns a key-value mapping associated with the least key greater than or equal to the given key, ornullif there is no such key.KceilingKey(K key)Returns the least key greater than or equal to the given key, ornullif there is no such key.voidclear()Removes all of the mappings from this map.Objectclone()Returns a shallow copy of thisTreeMapinstance.booleancontainsKey(Object key)Returnstrueif this map contains a mapping for the specified key.booleancontainsValue(Object value)Returnstrueif this map maps one or more keys to the specified value.NavigableSet<K>descendingKeySet()Returns a reverse orderNavigableSetview of the keys contained in this map.NavigableMap<K,V>descendingMap()Returns a reverse order view of the mappings contained in this map.Set<Map.Entry<K,V>>entrySet()Returns aSetview of the mappings contained in this map.Map.Entry<K,V>firstEntry()Returns a key-value mapping associated with the least key in this map, ornullif the map is empty.KfirstKey()Returns the first (lowest) key currently in this map.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, ornullif there is no such key.KfloorKey(K key)Returns the greatest key less than or equal to the given key, ornullif there is no such key.Vget(Object key)Returns the value to which the specified key is mapped, ornullif 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 thantoKey.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, ifinclusiveis true)toKey.Map.Entry<K,V>higherEntry(K key)Returns a key-value mapping associated with the least key strictly greater than the given key, ornullif there is no such key.KhigherKey(K key)Returns the least key strictly greater than the given key, ornullif there is no such key.Set<K>keySet()Returns aSetview of the keys contained in this map.Map.Entry<K,V>lastEntry()Returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty.KlastKey()Returns the last (highest) key currently in this map.Map.Entry<K,V>lowerEntry(K key)Returns a key-value mapping associated with the greatest key strictly less than the given key, ornullif there is no such key.KlowerKey(K key)Returns the greatest key strictly less than the given key, ornullif there is no such key.NavigableSet<K>navigableKeySet()Returns aNavigableSetview of the keys contained in this map.Map.Entry<K,V>pollFirstEntry()Removes and returns a key-value mapping associated with the least key in this map, ornullif the map is empty.Map.Entry<K,V>pollLastEntry()Removes and returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty.Vput(K key, V value)Associates the specified value with the specified key in this map.voidputAll(Map<? extends K,? extends V> map)Copies all of the mappings from the specified map to this map.Vremove(Object key)Removes the mapping for this key from this TreeMap if present.intsize()Returns the number of key-value mappings in this map.NavigableMap<K,V>subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)Returns a view of the portion of this map whose keys range fromfromKeytotoKey.SortedMap<K,V>subMap(K fromKey, K toKey)Returns a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive.SortedMap<K,V>tailMap(K fromKey)Returns a view of the portion of this map whose keys are greater than or equal tofromKey.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, ifinclusiveis true)fromKey.Collection<V>values()Returns aCollectionview of the values contained in this map.- 
Methods declared in class java.util.AbstractMapequals, hashCode, isEmpty, toString
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Methods declared in interface java.util.Mapcompute, computeIfAbsent, computeIfPresent, equals, forEach, getOrDefault, hashCode, isEmpty, merge, putIfAbsent, remove, replace, replace, replaceAll
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Methods declared in interface java.util.SortedMapcomparator
 
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Constructor Detail- 
TreeMappublic TreeMap() Constructs a new, empty tree map, using the natural ordering of its keys. All keys inserted into the map must implement theComparableinterface. Furthermore, all such keys must be mutually comparable:k1.compareTo(k2)must not throw aClassCastExceptionfor any keysk1andk2in 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), theput(Object key, Object value)call will throw aClassCastException.
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TreeMappublic 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 aClassCastExceptionfor any keysk1andk2in the map. If the user attempts to put a key into the map that violates this constraint, theput(Object key, Object value)call will throw aClassCastException.- Parameters:
- comparator- the comparator that will be used to order this map. If- null, the natural ordering of the keys will be used.
 
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TreeMappublic 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 theComparableinterface. Furthermore, all such keys must be mutually comparable:k1.compareTo(k2)must not throw aClassCastExceptionfor any keysk1andk2in the map. This method runs in n*log(n) time.- Parameters:
- m- 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
 
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TreeMappublic 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- 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
 
 
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Method Detail- 
sizepublic int size() Returns the number of key-value mappings in this map.
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containsKeypublic boolean containsKey(Object key) Returnstrueif this map contains a mapping for the specified key.- Specified by:
- containsKeyin interface- Map<K,V>
- Overrides:
- containsKeyin class- AbstractMap<K,V>
- Parameters:
- key- key whose presence in this map is to be tested
- Returns:
- trueif 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
 
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containsValuepublic boolean containsValue(Object value) Returnstrueif this map maps one or more keys to the specified value. More formally, returnstrueif and only if this map contains at least one mapping to a valuevsuch that(value==null ? v==null : value.equals(v)). This operation will probably require time linear in the map size for most implementations.- Specified by:
- containsValuein interface- Map<K,V>
- Overrides:
- containsValuein class- AbstractMap<K,V>
- Parameters:
- value- value whose presence in this map is to be tested
- Returns:
- trueif a mapping to- valueexists;- falseotherwise
- Since:
- 1.2
 
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getpublic V get(Object key) Returns the value to which the specified key is mapped, ornullif this map contains no mapping for the key.More formally, if this map contains a mapping from a key kto a valuevsuch thatkeycompares equal tokaccording to the map's ordering, then this method returnsv; otherwise it returnsnull. (There can be at most one such mapping.)A return value of nulldoes not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key tonull. ThecontainsKeyoperation may be used to distinguish these two cases.- Specified by:
- getin interface- Map<K,V>
- Overrides:
- getin class- AbstractMap<K,V>
- Parameters:
- key- the key whose associated value is to be returned
- Returns:
- the value to which the specified key is mapped, or
         nullif 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
 
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firstKeypublic K firstKey() Description copied from interface:SortedMapReturns the first (lowest) key currently in this map.- Specified by:
- firstKeyin interface- SortedMap<K,V>
- Returns:
- the first (lowest) key currently in this map
- Throws:
- NoSuchElementException- if this map is empty
 
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lastKeypublic K lastKey() Description copied from interface:SortedMapReturns the last (highest) key currently in this map.- Specified by:
- lastKeyin interface- SortedMap<K,V>
- Returns:
- the last (highest) key currently in this map
- Throws:
- NoSuchElementException- if this map is empty
 
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putAllpublic 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:
- putAllin interface- Map<K,V>
- Overrides:
- putAllin class- AbstractMap<K,V>
- Parameters:
- 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
 
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putpublic 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.- Specified by:
- putin interface- Map<K,V>
- Overrides:
- putin class- AbstractMap<K,V>
- Parameters:
- key- key with which the specified value is to be associated
- value- value to be associated with the specified key
- Returns:
- the previous value associated with key, ornullif there was no mapping forkey. (Anullreturn can also indicate that the map previously associatednullwithkey.)
- 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
 
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removepublic V remove(Object key) Removes the mapping for this key from this TreeMap if present.- Specified by:
- removein interface- Map<K,V>
- Overrides:
- removein class- AbstractMap<K,V>
- Parameters:
- key- key for which mapping should be removed
- Returns:
- the previous value associated with key, ornullif there was no mapping forkey. (Anullreturn can also indicate that the map previously associatednullwithkey.)
- 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
 
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clearpublic void clear() Removes all of the mappings from this map. The map will be empty after this call returns.
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clonepublic Object clone() Returns a shallow copy of thisTreeMapinstance. (The keys and values themselves are not cloned.)- Overrides:
- clonein class- AbstractMap<K,V>
- Returns:
- a shallow copy of this map
- See Also:
- Cloneable
 
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firstEntrypublic Map.Entry<K,V> firstEntry() Description copied from interface:NavigableMapReturns a key-value mapping associated with the least key in this map, ornullif the map is empty.- Specified by:
- firstEntryin interface- NavigableMap<K,V>
- Returns:
- an entry with the least key,
         or nullif this map is empty
- Since:
- 1.6
 
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lastEntrypublic Map.Entry<K,V> lastEntry() Description copied from interface:NavigableMapReturns a key-value mapping associated with the greatest key in this map, ornullif the map is empty.- Specified by:
- lastEntryin interface- NavigableMap<K,V>
- Returns:
- an entry with the greatest key,
         or nullif this map is empty
- Since:
- 1.6
 
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pollFirstEntrypublic Map.Entry<K,V> pollFirstEntry() Description copied from interface:NavigableMapRemoves and returns a key-value mapping associated with the least key in this map, ornullif the map is empty.- Specified by:
- pollFirstEntryin interface- NavigableMap<K,V>
- Returns:
- the removed first entry of this map,
         or nullif this map is empty
- Since:
- 1.6
 
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pollLastEntrypublic Map.Entry<K,V> pollLastEntry() Description copied from interface:NavigableMapRemoves and returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty.- Specified by:
- pollLastEntryin interface- NavigableMap<K,V>
- Returns:
- the removed last entry of this map,
         or nullif this map is empty
- Since:
- 1.6
 
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lowerEntrypublic Map.Entry<K,V> lowerEntry(K key) Description copied from interface:NavigableMapReturns a key-value mapping associated with the greatest key strictly less than the given key, ornullif there is no such key.- Specified by:
- lowerEntryin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- an entry with the greatest key less than key, ornullif 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
 
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lowerKeypublic K lowerKey(K key) Description copied from interface:NavigableMapReturns the greatest key strictly less than the given key, ornullif there is no such key.- Specified by:
- lowerKeyin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- the greatest key less than key, ornullif 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
 
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floorEntrypublic Map.Entry<K,V> floorEntry(K key) Description copied from interface:NavigableMapReturns a key-value mapping associated with the greatest key less than or equal to the given key, ornullif there is no such key.- Specified by:
- floorEntryin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- an entry with the greatest key less than or equal to
         key, ornullif 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
 
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floorKeypublic K floorKey(K key) Description copied from interface:NavigableMapReturns the greatest key less than or equal to the given key, ornullif there is no such key.- Specified by:
- floorKeyin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- the greatest key less than or equal to key, ornullif 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
 
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ceilingEntrypublic Map.Entry<K,V> ceilingEntry(K key) Description copied from interface:NavigableMapReturns a key-value mapping associated with the least key greater than or equal to the given key, ornullif there is no such key.- Specified by:
- ceilingEntryin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- an entry with the least key greater than or equal to
         key, ornullif 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
 
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ceilingKeypublic K ceilingKey(K key) Description copied from interface:NavigableMapReturns the least key greater than or equal to the given key, ornullif there is no such key.- Specified by:
- ceilingKeyin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- the least key greater than or equal to key, ornullif 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
 
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higherEntrypublic Map.Entry<K,V> higherEntry(K key) Description copied from interface:NavigableMapReturns a key-value mapping associated with the least key strictly greater than the given key, ornullif there is no such key.- Specified by:
- higherEntryin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- an entry with the least key greater than key, ornullif 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
 
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higherKeypublic K higherKey(K key) Description copied from interface:NavigableMapReturns the least key strictly greater than the given key, ornullif there is no such key.- Specified by:
- higherKeyin interface- NavigableMap<K,V>
- Parameters:
- key- the key
- Returns:
- the least key greater than key, ornullif 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
 
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keySetpublic Set<K> keySet() Returns aSetview 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 Spliterator.SORTEDandSpliterator.ORDEREDwith an encounter order that is ascending key order. The spliterator's comparator (seeSpliterator.getComparator()) isnullif the tree map's comparator (seeSortedMap.comparator()) isnull. 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 removeoperation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Set.remove,removeAll,retainAll, andclearoperations. It does not support theaddoraddAlloperations.
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navigableKeySetpublic NavigableSet<K> navigableKeySet() Description copied from interface:NavigableMapReturns aNavigableSetview 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 ownremoveoperation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Set.remove,removeAll,retainAll, andclearoperations. It does not support theaddoraddAlloperations.- Specified by:
- navigableKeySetin interface- NavigableMap<K,V>
- Returns:
- a navigable set view of the keys in this map
- Since:
- 1.6
 
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descendingKeySetpublic NavigableSet<K> descendingKeySet() Description copied from interface:NavigableMapReturns a reverse orderNavigableSetview 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 ownremoveoperation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Set.remove,removeAll,retainAll, andclearoperations. It does not support theaddoraddAlloperations.- Specified by:
- descendingKeySetin interface- NavigableMap<K,V>
- Returns:
- a reverse order navigable set view of the keys in this map
- Since:
- 1.6
 
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valuespublic Collection<V> values() Returns aCollectionview 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 Spliterator.ORDEREDwith 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 removeoperation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via theIterator.remove,Collection.remove,removeAll,retainAllandclearoperations. It does not support theaddoraddAlloperations.
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entrySetpublic Set<Map.Entry<K,V>> entrySet() Returns aSetview of the mappings contained in this map.The set's iterator returns the entries in ascending key order. The set's spliterator is late-binding, fail-fast, and additionally reports Spliterator.SORTEDandSpliterator.ORDEREDwith 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 removeoperation, or through thesetValueoperation 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 theIterator.remove,Set.remove,removeAll,retainAllandclearoperations. It does not support theaddoraddAlloperations.
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descendingMappublic NavigableMap<K,V> descendingMap() Description copied from interface:NavigableMapReturns 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 ownremoveoperation), the results of the iteration are undefined.The returned map has an ordering equivalent to Collections.reverseOrder(comparator()). The expressionm.descendingMap().descendingMap()returns a view ofmessentially equivalent tom.- Specified by:
- descendingMapin interface- NavigableMap<K,V>
- Returns:
- a reverse order view of this map
- Since:
- 1.6
 
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subMappublic NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys range fromfromKeytotoKey. IffromKeyandtoKeyare equal, the returned map is empty unlessfromInclusiveandtoInclusiveare 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 IllegalArgumentExceptionon an attempt to insert a key outside of its range, or to construct a submap either of whose endpoints lie outside its range.- Specified by:
- subMapin interface- NavigableMap<K,V>
- Parameters:
- fromKey- low endpoint of the keys in the returned map
- fromInclusive-- trueif the low endpoint is to be included in the returned view
- toKey- high endpoint of the keys in the returned map
- toInclusive-- trueif the high endpoint is to be included in the returned view
- Returns:
- a view of the portion of this map whose keys range from
         fromKeytotoKey
- Throws:
- ClassCastException- if- fromKeyand- toKeycannot 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- fromKeyor- toKeycannot be compared to keys currently in the map.
- NullPointerException- if- fromKeyor- toKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if- fromKeyis greater than- toKey; or if this map itself has a restricted range, and- fromKeyor- toKeylies outside the bounds of the range
- Since:
- 1.6
 
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headMappublic NavigableMap<K,V> headMap(K toKey, boolean inclusive) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys are less than (or equal to, ifinclusiveis 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 IllegalArgumentExceptionon an attempt to insert a key outside its range.- Specified by:
- headMapin interface- NavigableMap<K,V>
- Parameters:
- toKey- high endpoint of the keys in the returned map
- inclusive-- trueif the high endpoint is to be included in the returned view
- Returns:
- a view of the portion of this map whose keys are less than
         (or equal to, if inclusiveis true)toKey
- Throws:
- ClassCastException- if- toKeyis not compatible with this map's comparator (or, if the map has no comparator, if- toKeydoes not implement- Comparable). Implementations may, but are not required to, throw this exception if- toKeycannot be compared to keys currently in the map.
- NullPointerException- if- toKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if this map itself has a restricted range, and- toKeylies outside the bounds of the range
- Since:
- 1.6
 
 - 
tailMappublic NavigableMap<K,V> tailMap(K fromKey, boolean inclusive) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys are greater than (or equal to, ifinclusiveis 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 IllegalArgumentExceptionon an attempt to insert a key outside its range.- Specified by:
- tailMapin interface- NavigableMap<K,V>
- Parameters:
- fromKey- low endpoint of the keys in the returned map
- inclusive-- trueif the low endpoint is to be included in the returned view
- Returns:
- a view of the portion of this map whose keys are greater than
         (or equal to, if inclusiveis true)fromKey
- Throws:
- ClassCastException- if- fromKeyis not compatible with this map's comparator (or, if the map has no comparator, if- fromKeydoes not implement- Comparable). Implementations may, but are not required to, throw this exception if- fromKeycannot be compared to keys currently in the map.
- NullPointerException- if- fromKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if this map itself has a restricted range, and- fromKeylies outside the bounds of the range
- Since:
- 1.6
 
 - 
subMappublic SortedMap<K,V> subMap(K fromKey, K toKey) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive. (IffromKeyandtoKeyare 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 IllegalArgumentExceptionon an attempt to insert a key outside its range.Equivalent to subMap(fromKey, true, toKey, false).- Specified by:
- subMapin interface- NavigableMap<K,V>
- Specified by:
- subMapin interface- SortedMap<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, totoKey, exclusive
- Throws:
- ClassCastException- if- fromKeyand- toKeycannot 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- fromKeyor- toKeycannot be compared to keys currently in the map.
- NullPointerException- if- fromKeyor- toKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if- fromKeyis greater than- toKey; or if this map itself has a restricted range, and- fromKeyor- toKeylies outside the bounds of the range
 
 - 
headMappublic SortedMap<K,V> headMap(K toKey) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys are strictly less thantoKey. 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 IllegalArgumentExceptionon an attempt to insert a key outside its range.Equivalent to headMap(toKey, false).- Specified by:
- headMapin interface- NavigableMap<K,V>
- Specified by:
- headMapin interface- SortedMap<K,V>
- Parameters:
- toKey- high endpoint (exclusive) of the keys in the returned map
- Returns:
- a view of the portion of this map whose keys are strictly
         less than toKey
- Throws:
- ClassCastException- if- toKeyis not compatible with this map's comparator (or, if the map has no comparator, if- toKeydoes not implement- Comparable). Implementations may, but are not required to, throw this exception if- toKeycannot be compared to keys currently in the map.
- NullPointerException- if- toKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if this map itself has a restricted range, and- toKeylies outside the bounds of the range
 
 - 
tailMappublic SortedMap<K,V> tailMap(K fromKey) Description copied from interface:NavigableMapReturns a view of the portion of this map whose keys are greater than or equal tofromKey. 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 IllegalArgumentExceptionon an attempt to insert a key outside its range.Equivalent to tailMap(fromKey, true).- Specified by:
- tailMapin interface- NavigableMap<K,V>
- Specified by:
- tailMapin interface- SortedMap<K,V>
- Parameters:
- fromKey- low endpoint (inclusive) of the keys in the returned map
- Returns:
- a view of the portion of this map whose keys are greater
         than or equal to fromKey
- Throws:
- ClassCastException- if- fromKeyis not compatible with this map's comparator (or, if the map has no comparator, if- fromKeydoes not implement- Comparable). Implementations may, but are not required to, throw this exception if- fromKeycannot be compared to keys currently in the map.
- NullPointerException- if- fromKeyis null and this map uses natural ordering, or its comparator does not permit null keys
- IllegalArgumentException- if this map itself has a restricted range, and- fromKeylies outside the bounds of the range
 
 
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