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 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
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.
Public Constructors | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Constructs a new, empty tree map, using the natural ordering of its
keys.
| |||||||||||
Constructs a new, empty tree map, ordered according to the given
comparator.
| |||||||||||
Constructs a new tree map containing the same mappings as the given
map, ordered according to the natural ordering of its keys.
| |||||||||||
Constructs a new tree map containing the same mappings and
using the same ordering as the specified sorted map.
|
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
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. | |||||||||||
Returns the least key greater than or equal to the given key,
or
null if there is no such key. | |||||||||||
Removes all of the mappings from this map.
| |||||||||||
Returns a shallow copy of this TreeMap instance.
| |||||||||||
Returns the comparator used to order the keys in this map, or
null if this map uses the
natural ordering of its keys. | |||||||||||
Returns true if this map contains a mapping for the specified
key.
| |||||||||||
Returns true if this map maps one or more keys to the
specified value.
| |||||||||||
Returns a reverse order
NavigableSet view of the keys contained in this map. | |||||||||||
Returns a reverse order view of the mappings contained in this map.
| |||||||||||
Returns a
Set view of the mappings contained in this map. | |||||||||||
Returns a key-value mapping associated with the least
key in this map, or
null if the map is empty. | |||||||||||
Returns the first (lowest) key currently in this map.
| |||||||||||
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. | |||||||||||
Returns the greatest key less than or equal to the given key,
or
null if there is no such key. | |||||||||||
Returns the value to which the specified key is mapped,
or
null if this map contains no mapping for the key. | |||||||||||
Returns a view of the portion of this map whose keys are less than (or
equal to, if
inclusive is true) toKey . | |||||||||||
Returns a view of the portion of this map whose keys are
strictly less than toKey.
Equivalent to | |||||||||||
Returns a key-value mapping associated with the least key
strictly greater than the given key, or
null if there
is no such key. | |||||||||||
Returns the least key strictly greater than the given key, or
null if there is no such key. | |||||||||||
Returns a
Set view of the keys contained in this map. | |||||||||||
Returns a key-value mapping associated with the greatest
key in this map, or
null if the map is empty. | |||||||||||
Returns the last (highest) key currently in this map.
| |||||||||||
Returns a key-value mapping associated with the greatest key
strictly less than the given key, or
null if there is
no such key. | |||||||||||
Returns the greatest key strictly less than the given key, or
null if there is no such key. | |||||||||||
Returns a
NavigableSet view of the keys contained in this map. | |||||||||||
Removes and returns a key-value mapping associated with
the least key in this map, or
null if the map is empty. | |||||||||||
Removes and returns a key-value mapping associated with
the greatest key in this map, or
null if the map is empty. | |||||||||||
Associates the specified value with the specified key in this map.
| |||||||||||
Copies all of the mappings from the specified map to this map.
| |||||||||||
Removes the mapping for this key from this TreeMap if present.
| |||||||||||
Returns the number of key-value mappings in this map.
| |||||||||||
Returns a view of the portion of this map whose keys range from
fromKey, inclusive, to toKey, exclusive.
Equivalent to | |||||||||||
Returns a view of the portion of this map whose keys range from
fromKey to toKey . | |||||||||||
Returns a view of the portion of this map whose keys are greater than (or
equal to, if
inclusive is true) fromKey . | |||||||||||
Returns a view of the portion of this map whose keys are
greater than or equal to fromKey.
Equivalent to | |||||||||||
Returns a
Collection view of the values contained in this map. |
[Expand]
Inherited Methods | |||||||||||
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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
|
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.
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.
comparator | the comparator that will be used to order this map.
If null, the natural
ordering of the keys will be used.
|
---|
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.
m | the map whose mappings are to be placed in this map |
---|
ClassCastException | if the keys in m are not Comparable ,
or are not mutually comparable |
---|---|
NullPointerException | if the specified map is null |
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.
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 map is null |
---|
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.
key | the key |
---|
key
, or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Returns the least key greater than or equal to the given key,
or null
if there is no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Removes all of the mappings from this map. The map will be empty after this call returns.
Returns a shallow copy of this TreeMap instance. (The keys and values themselves are not cloned.)
Returns the comparator used to order the keys in this map, or
null if this map uses the natural ordering
of its keys.
Returns true if this map contains a mapping for the specified key.
key | key whose presence in this map is to be tested |
---|
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 |
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.
value | value whose presence in this map is to be tested |
---|
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 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 a Set
view of the mappings contained in this map.
The set's iterator returns the entries in 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 a key-value mapping associated with the least
key in this map, or null
if the map is empty.
null
if this map is empty
Returns the first (lowest) key currently in this map.
NoSuchElementException |
---|
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.
key | the key |
---|
key
, or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Returns the greatest key less than or equal to the given key,
or null
if there is no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
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.
key | the key whose associated value is to be returned |
---|
null
if this map contains no mapping for the keyClassCastException | 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 |
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.
toKey | high endpoint of the keys in the returned map |
---|---|
inclusive | true if the high endpoint
is to be included in the returned view |
inclusive
is true) toKey
ClassCastException | |
---|---|
NullPointerException | if toKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
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)
.
toKey | high endpoint (exclusive) of the keys in the returned map |
---|
ClassCastException | |
---|---|
NullPointerException | if toKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
Returns a key-value mapping associated with the least key
strictly greater than the given key, or null
if there
is no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Returns the least key strictly greater than the given key, or
null
if there is no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Returns a Set
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 a key-value mapping associated with the greatest
key in this map, or null
if the map is empty.
null
if this map is empty
Returns the last (highest) key currently in this map.
NoSuchElementException |
---|
Returns a key-value mapping associated with the greatest key
strictly less than the given key, or null
if there is
no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
Returns the greatest key strictly less than the given key, or
null
if there is no such key.
key | the key |
---|
key
,
or null
if there is no such keyClassCastException | |
---|---|
NullPointerException | if the specified key is null and this map uses natural ordering, or its comparator does not permit null keys |
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.
Removes and returns a key-value mapping associated with
the least key in this map, or null
if the map is empty.
null
if this map is empty
Removes and returns a key-value mapping associated with
the greatest key in this map, or null
if the map is empty.
null
if this map is empty
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.
key | key with which the specified value is to be associated |
---|---|
value | value to be associated with the specified key |
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 |
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.
map | mappings to be stored in this map |
---|
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 |
Removes the mapping for this key from this TreeMap if present.
key | key for which mapping should be removed |
---|
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 |
Returns the number of key-value mappings in this map.
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)
.
fromKey | low endpoint (inclusive) of the keys in the returned map |
---|---|
toKey | high endpoint (exclusive) of the keys in the returned map |
ClassCastException | |
---|---|
NullPointerException | if fromKey or toKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
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
fromExclusive
and toExclusive
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.
fromKey | low endpoint of the keys in the returned map |
---|---|
fromInclusive | true if the low endpoint
is to be included in the returned view |
toKey | high endpoint of the keys in the returned map |
toInclusive | true if the high endpoint
is to be included in the returned view |
fromKey
to toKey
ClassCastException | |
---|---|
NullPointerException | if fromKey or toKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
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.
fromKey | low endpoint of the keys in the returned map |
---|---|
inclusive | true if the low endpoint
is to be included in the returned view |
inclusive
is true) fromKey
ClassCastException | |
---|---|
NullPointerException | if fromKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
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)
.
fromKey | low endpoint (inclusive) of the keys in the returned map |
---|
ClassCastException | |
---|---|
NullPointerException | if fromKey is null and this map uses natural ordering, or its comparator does not permit null keys |
IllegalArgumentException |
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 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.