java.lang.Object
java.util.AbstractMap<K,V>
java.util.TreeMap<K,V>
public class TreeMap<K,V>
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.synchronizedMap method. This is best done at creation time, to prevent accidental unsynchronized access to the map:
Map m = Collections.synchronizedMap(new TreeMap(...));
The iterators 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 or add methods, the iterator throws 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.
This class is a member of the Java Collections Framework.
Map, HashMap, Hashtable, Comparable, Comparator, Collection, Collections.synchronizedMap(Map), Serialized Form
TreeMap()
TreeMap(Comparator<? super K> c)
TreeMap(Map<? extends K,? extends V> m)
TreeMap(SortedMap<K,? extends V> m)
void clear()
Object clone()
Comparator<? super K> comparator()
boolean containsKey(Object key)
boolean containsValue(Object value)
Set<Map.Entry<K,V>> entrySet()
K firstKey()
V get(Object key)
SortedMap<K,V> headMap(K toKey)
Set<K> keySet()
K lastKey()
V put(K key, V value)
void putAll(Map<? extends K,? extends V> map)
V remove(Object key)
int size()
SortedMap<K,V> subMap(K fromKey, K toKey)
SortedMap<K,V> tailMap(K fromKey)
Collection<V> values()
public TreeMap()
Comparable
public TreeMap(Comparator<? super K> c)
c - the comparator that will be used to sort this map. A null value indicates that the keys' natural ordering should be used.
public TreeMap(Map<? extends K,? extends V> m)
m - the map whose mappings are to be placed in this map.
ClassCastException - the keys in t are not Comparable, or are not mutually comparable.
NullPointerException - if the specified map is null.
public TreeMap(SortedMap<K,? extends V> m)
m - the sorted map whose mappings are to be placed in this map, and whose comparator is to be used to sort this map.
NullPointerException - if the specified sorted map is null.
public int size()
size in interface Map<K,V>
size in class AbstractMap<K,V>
public boolean containsKey(Object key)
containsKey in interface Map<K,V>
containsKey in class AbstractMap<K,V>
key - key whose presence in this map is to be tested.
ClassCastException - if the key cannot be compared with the keys currently in the map.
NullPointerException - key is null and this map uses natural ordering, or its comparator does not tolerate null keys.
public boolean containsValue(Object value)
containsValue in interface Map<K,V>
containsValue in class AbstractMap<K,V>
value - value whose presence in this Map is to be tested.
public V get(Object key)
get in interface Map<K,V>
get in class AbstractMap<K,V>
key - key whose associated value is to be returned.
ClassCastException - key cannot be compared with the keys currently in the map.
NullPointerException - key is null and this map uses natural ordering, or its comparator does not tolerate null keys.
containsKey(Object)
public Comparator<? super K> comparator()
comparator in interface SortedMap<K,V>
public K firstKey()
firstKey in interface SortedMap<K,V>
NoSuchElementException - Map is empty.
public K lastKey()
lastKey in interface SortedMap<K,V>
NoSuchElementException - Map is empty.
public void putAll(Map<? extends K,? extends V> map)
putAll in interface Map<K,V>
putAll in class AbstractMap<K,V>
map - mappings to be stored in this map.
ClassCastException - class of a key or value in the specified map prevents it from being stored in this map.
NullPointerException - if the given map is null or this map does not permit null keys and a key in the specified map is null.
public V put(K key,
V value)
put in interface Map<K,V>
put in class AbstractMap<K,V>
key - key with which the specified value is to be associated.
value - value to be associated with the specified key.
ClassCastException - key cannot be compared with the keys currently in the map.
NullPointerException - key is null and this map uses natural order, or its comparator does not tolerate null keys.
public V remove(Object key)
remove in interface Map<K,V>
remove in class AbstractMap<K,V>
key - key for which mapping should be removed
ClassCastException - key cannot be compared with the keys currently in the map.
NullPointerException - key is null and this map uses natural order, or its comparator does not tolerate null keys.
public void clear()
clear in interface Map<K,V>
clear in class AbstractMap<K,V>
public Object clone()
clone in class AbstractMap<K,V>
Cloneable
public Set<K> keySet()
keySet in interface Map<K,V>
keySet in class AbstractMap<K,V>
public Collection<V> values()
values in interface Map<K,V>
values in class AbstractMap<K,V>
public Set<Map.Entry<K,V>> entrySet()
entrySet in interface Map<K,V>
entrySet in class AbstractMap<K,V>
Map.Entry
public SortedMap<K,V> subMap(K fromKey,
K toKey)
The sorted map returned by this method will throw an IllegalArgumentException if the user attempts to insert a key less than fromKey or greater than or equal to toKey.
Note: this method always returns a half-open range (which includes its low endpoint but not its high endpoint). If you need a closed range (which includes both endpoints), and the key type allows for calculation of the successor a given key, merely request the subrange from lowEndpoint to successor(highEndpoint). For example, suppose that m is a sorted map whose keys are strings. The following idiom obtains a view containing all of the key-value mappings in m whose keys are between low and high, inclusive:
SortedMap sub = m.submap(low, high+"\0");A similar technique can be used to generate an open range (which contains neither endpoint). The following idiom obtains a view containing all of the key-value mappings in m whose keys are between low and high, exclusive:
SortedMap sub = m.subMap(low+"\0", high);
subMap in interface SortedMap<K,V>
fromKey - low endpoint (inclusive) of the subMap.
toKey - high endpoint (exclusive) of the subMap.
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).
IllegalArgumentException - if fromKey is greater than toKey.
NullPointerException - if fromKey or toKey is null and this map uses natural order, or its comparator does not tolerate null keys.
public SortedMap<K,V> headMap(K toKey)
The sorted map returned by this method will throw an IllegalArgumentException if the user attempts to insert a key greater than or equal to toKey.
Note: this method always returns a view that does not contain its (high) endpoint. If you need a view that does contain this endpoint, and the key type allows for calculation of the successor a given key, merely request a headMap bounded by successor(highEndpoint). For example, suppose that suppose that m is a sorted map whose keys are strings. The following idiom obtains a view containing all of the key-value mappings in m whose keys are less than or equal to high:
SortedMap head = m.headMap(high+"\0");
headMap in interface SortedMap<K,V>
toKey - high endpoint (exclusive) of the headMap.
ClassCastException - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable).
IllegalArgumentException - if this map is itself a subMap, headMap, or tailMap, and toKey is not within the specified range of the subMap, headMap, or tailMap.
NullPointerException - if toKey is null and this map uses natural order, or its comparator does not tolerate null keys.
public SortedMap<K,V> tailMap(K fromKey)
The sorted map returned by this method will throw an IllegalArgumentException if the user attempts to insert a key less than fromKey.
Note: this method always returns a view that contains its (low) endpoint. If you need a view that does not contain this endpoint, and the element type allows for calculation of the successor a given value, merely request a tailMap bounded by successor(lowEndpoint). For example, suppose that m is a sorted map whose keys are strings. The following idiom obtains a view containing all of the key-value mappings in m whose keys are strictly greater than low:
SortedMap tail = m.tailMap(low+"\0");
tailMap in interface SortedMap<K,V>
fromKey - low endpoint (inclusive) of the tailMap.
ClassCastException - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable).
IllegalArgumentException - if this map is itself a subMap, headMap, or tailMap, and fromKey is not within the specified range of the subMap, headMap, or tailMap.
NullPointerException - if fromKey is null and this map uses natural order, or its comparator does not tolerate null keys.
Copyright © 2004, 2010 Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
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