Interface NavigableMap<K,V>
- Type Parameters:
K- the type of keys maintained by this mapV- the type of mapped values
- All Superinterfaces:
Map<K,,V> SequencedMap<K,,V> SortedMap<K,V>
- All Known Subinterfaces:
ConcurrentNavigableMap<K,V>
- All Known Implementing Classes:
ConcurrentSkipListMap,TreeMap
SortedMap extended with navigation methods returning the
closest matches for given search targets. Methods
lowerEntry(K), floorEntry(K), ceilingEntry(K),
and higherEntry(K) return Map.Entry objects
associated with keys respectively less than, less than or equal,
greater than or equal, and greater than a given key, returning
null if there is no such key. Similarly, methods
lowerKey(K), floorKey(K), ceilingKey(K), and
higherKey(K) return only the associated keys. All of these
methods are designed for locating, not traversing entries.
A NavigableMap may be accessed and traversed in either
ascending or descending key order. The descendingMap()
method returns a view of the map with the senses of all relational
and directional methods inverted. The performance of ascending
operations and views is likely to be faster than that of descending
ones. Methods
subMap(K, boolean, K, boolean),
headMap(K, boolean), and
tailMap(K, boolean)
differ from the like-named SortedMap methods in accepting
additional arguments describing whether lower and upper bounds are
inclusive versus exclusive. Submaps of any NavigableMap
must implement the NavigableMap interface.
This interface additionally defines methods firstEntry(),
pollFirstEntry(), lastEntry(), and
pollLastEntry() that return and/or remove the least and
greatest mappings, if any exist, else returning null.
The methods
ceilingEntry(K),
firstEntry(),
floorEntry(K),
higherEntry(K),
lastEntry(),
lowerEntry(K),
pollFirstEntry(), and
pollLastEntry()
return Map.Entry instances that represent snapshots of mappings as
of the time of the call. They do not support mutation of the
underlying map via the optional setValue method.
Methods
subMap(K, K),
headMap(K), and
tailMap(K)
are specified to return SortedMap to allow existing
implementations of SortedMap to be compatibly retrofitted to
implement NavigableMap, but extensions and implementations
of this interface are encouraged to override these methods to return
NavigableMap. Similarly,
SortedMap.keySet() can be overridden to return NavigableSet.
This interface is a member of the Java Collections Framework.
- Since:
- 1.6
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Nested Class Summary
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Method Summary
Modifier and TypeMethodDescriptionceilingEntry(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.ceilingKey(K key) Returns the least key greater than or equal to the given key, ornullif there is no such key.Returns a reverse orderNavigableSetview of the keys contained in this map.Returns a reverse order view of the mappings contained in this map.Returns a key-value mapping associated with the least key in this map, ornullif the map is empty.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.Returns the greatest key less than or equal to the given key, ornullif there is no such key.Returns a view of the portion of this map whose keys are strictly less thantoKey.Returns a view of the portion of this map whose keys are less than (or equal to, ifinclusiveis true)toKey.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.Returns the least key strictly greater than the given key, ornullif there is no such key.Returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty.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.Returns the greatest key strictly less than the given key, ornullif there is no such key.Returns aNavigableSetview of the keys contained in this map.Removes and returns a key-value mapping associated with the least key in this map, ornullif the map is empty (optional operation).Removes and returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty (optional operation).default NavigableMap<K, V> reversed()Returns a reverse-ordered view of this map.Returns a view of the portion of this map whose keys range fromfromKeytotoKey.Returns a view of the portion of this map whose keys range fromfromKey, inclusive, totoKey, exclusive.Returns a view of the portion of this map whose keys are greater than or equal tofromKey.Returns a view of the portion of this map whose keys are greater than (or equal to, ifinclusiveis true)fromKey.Methods declared in interface java.util.Map
clear, compute, computeIfAbsent, computeIfPresent, containsKey, containsValue, equals, forEach, get, getOrDefault, hashCode, isEmpty, merge, put, putAll, putIfAbsent, remove, remove, replace, replace, replaceAll, sizeMethods declared in interface java.util.SequencedMap
sequencedEntrySet, sequencedKeySet, sequencedValues
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Method Details
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lowerEntry
Returns a key-value mapping associated with the greatest key strictly less than the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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lowerKey
Returns the greatest key strictly less than the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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floorEntry
Returns a key-value mapping associated with the greatest key less than or equal to the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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floorKey
Returns the greatest key less than or equal to the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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ceilingEntry
Returns a key-value mapping associated with the least key greater than or equal to the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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ceilingKey
Returns the least key greater than or equal to the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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higherEntry
Returns a key-value mapping associated with the least key strictly greater than the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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higherKey
Returns the least key strictly greater than the given key, ornullif there is no such key.- 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 mapNullPointerException- if the specified key is null and this map does not permit null keys
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firstEntry
Returns a key-value mapping associated with the least key in this map, ornullif the map is empty.- Specified by:
firstEntryin interfaceSequencedMap<K,V> - Returns:
- an entry with the least key,
or
nullif this map is empty
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lastEntry
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pollFirstEntry
Removes and returns a key-value mapping associated with the least key in this map, ornullif the map is empty (optional operation).- Specified by:
pollFirstEntryin interfaceSequencedMap<K,V> - Returns:
- the removed first entry of this map,
or
nullif this map is empty - Throws:
UnsupportedOperationException- if thepollFirstEntryoperation is not supported by this map
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pollLastEntry
Removes and returns a key-value mapping associated with the greatest key in this map, ornullif the map is empty (optional operation).- Specified by:
pollLastEntryin interfaceSequencedMap<K,V> - Returns:
- the removed last entry of this map,
or
nullif this map is empty - Throws:
UnsupportedOperationException- if thepollLastEntryoperation is not supported by this map
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descendingMap
NavigableMap<K,V> descendingMap()Returns a reverse order view of the mappings contained in this map. The descending map is backed by this map, so changes to the map are reflected in the descending map, and vice-versa. If either map is modified while an iteration over a collection view of either map is in progress (except through the iterator's 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.- Returns:
- a reverse order view of this map
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descendingKeySet
NavigableSet<K> descendingKeySet()Returns 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.- Returns:
- a reverse order navigable set view of the keys in this map
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subMap
Returns 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.- Parameters:
fromKey- low endpoint of the keys in the returned mapfromInclusive-trueif the low endpoint is to be included in the returned viewtoKey- high endpoint of the keys in the returned maptoInclusive-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- iffromKeyandtoKeycannot 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 iffromKeyortoKeycannot be compared to keys currently in the map.NullPointerException- iffromKeyortoKeyis null and this map does not permit null keysIllegalArgumentException- iffromKeyis greater thantoKey; or if this map itself has a restricted range, andfromKeyortoKeylies outside the bounds of the range
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headMap
Returns 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.- Parameters:
toKey- high endpoint of the keys in the returned mapinclusive-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- iftoKeyis not compatible with this map's comparator (or, if the map has no comparator, iftoKeydoes not implementComparable). Implementations may, but are not required to, throw this exception iftoKeycannot be compared to keys currently in the map.NullPointerException- iftoKeyis null and this map does not permit null keysIllegalArgumentException- if this map itself has a restricted range, andtoKeylies outside the bounds of the range
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tailMap
Returns 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.- Parameters:
fromKey- low endpoint of the keys in the returned mapinclusive-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- iffromKeyis not compatible with this map's comparator (or, if the map has no comparator, iffromKeydoes not implementComparable). Implementations may, but are not required to, throw this exception iffromKeycannot be compared to keys currently in the map.NullPointerException- iffromKeyis null and this map does not permit null keysIllegalArgumentException- if this map itself has a restricted range, andfromKeylies outside the bounds of the range
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subMap
Returns 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 interfaceSortedMap<K,V> - Parameters:
fromKey- low endpoint (inclusive) of the keys in the returned maptoKey- 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- iffromKeyandtoKeycannot 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 iffromKeyortoKeycannot be compared to keys currently in the map.NullPointerException- iffromKeyortoKeyis null and this map does not permit null keysIllegalArgumentException- iffromKeyis greater thantoKey; or if this map itself has a restricted range, andfromKeyortoKeylies outside the bounds of the range
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headMap
Returns 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 interfaceSortedMap<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- iftoKeyis not compatible with this map's comparator (or, if the map has no comparator, iftoKeydoes not implementComparable). Implementations may, but are not required to, throw this exception iftoKeycannot be compared to keys currently in the map.NullPointerException- iftoKeyis null and this map does not permit null keysIllegalArgumentException- if this map itself has a restricted range, andtoKeylies outside the bounds of the range
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tailMap
Returns 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 interfaceSortedMap<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- iffromKeyis not compatible with this map's comparator (or, if the map has no comparator, iffromKeydoes not implementComparable). Implementations may, but are not required to, throw this exception iffromKeycannot be compared to keys currently in the map.NullPointerException- iffromKeyis null and this map does not permit null keysIllegalArgumentException- if this map itself has a restricted range, andfromKeylies outside the bounds of the range
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reversed
Returns a reverse-ordered view of this map. The encounter order of mappings in the returned view is the inverse of the encounter order of mappings in this map. The reverse ordering affects all order-sensitive operations, including those on the view collections of the returned view. If the implementation permits modifications to this view, the modifications "write through" to the underlying map. Changes to the underlying map might or might not be visible in this reversed view, depending upon the implementation.This method is equivalent to
descendingMap.
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