NavigableMap (Java Platform SE 6) (original) (raw)
java.util
Interface NavigableMap<K,V>
Type Parameters:
K - the type of keys maintained by this map
V - the type of mapped values
All Superinterfaces:
All Known Subinterfaces:
All Known Implementing Classes:
ConcurrentSkipListMap, TreeMap
public interface NavigableMap<K,V>
extends SortedMap<K,V>
A SortedMap extended with navigation methods returning the closest matches for given search targets. MethodslowerEntry, floorEntry, ceilingEntry, and higherEntry return Map.Entry objects associated with keys respectively less than, less than or equal, greater than or equal, and greater than a given key, returningnull if there is no such key. Similarly, methodslowerKey, floorKey, ceilingKey, andhigherKey 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, headMap, and tailMap 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, andpollLastEntry that return and/or remove the least and greatest mappings, if any exist, else returning null.
Implementations of entry-returning methods are expected to return Map.Entry pairs representing snapshots of mappings at the time they were produced, and thus generally do not support the optional Entry.setValue method. Note however that it is possible to change mappings in the associated map using method put.
Methods[subMap(K, K)](../../java/util/NavigableMap.html#subMap%28K, K%29),headMap(K), andtailMap(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 returnNavigableMap. Similarly,SortedMap.keySet() can be overriden to return NavigableSet.
This interface is a member of the Java Collections Framework.
Since:
1.6
| Nested Class Summary |
|---|
| Nested classes/interfaces inherited from interface java.util.Map |
|---|
| Map.Entry<K,V> |
| Method Summary | |
|---|---|
| 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, or null if there is no such key. |
| K | ceilingKey(K key) Returns the least key greater than or equal to the given key, or null if there is no such key. |
| NavigableSet<K> | descendingKeySet() Returns a reverse order NavigableSet view of the keys contained in this map. |
| NavigableMap<K,V> | descendingMap() Returns a reverse order view 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, or null if the map is empty. |
| 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, or null if there is no such key. |
| K | floorKey(K key) Returns the greatest key less than or equal to the given key, or null if there is no such key. |
| SortedMap<K,V> | headMap(K toKey) Returns a view of the portion of this map whose keys are strictly less than toKey. |
| NavigableMap<K,V> | [headMap](../../java/util/NavigableMap.html#headMap%28K, boolean%29)(K toKey, boolean inclusive) Returns a view of the portion of this map whose keys are less than (or equal to, if inclusive is 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, or null if there is no such key. |
| K | higherKey(K key) Returns the least key strictly greater than the given key, ornull if there is no such key. |
| Map.Entry<K,V> | lastEntry() Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. |
| Map.Entry<K,V> | lowerEntry(K key) Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key. |
| K | lowerKey(K key) Returns the greatest key strictly less than the given key, ornull if there is no such key. |
| NavigableSet<K> | navigableKeySet() Returns a NavigableSet view 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, or null if the map is empty. |
| Map.Entry<K,V> | pollLastEntry() Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty. |
| NavigableMap<K,V> | [subMap](../../java/util/NavigableMap.html#subMap%28K, boolean, K, boolean%29)(K fromKey, boolean fromInclusive,K toKey, boolean toInclusive) Returns a view of the portion of this map whose keys range fromfromKey to toKey. |
| SortedMap<K,V> | [subMap](../../java/util/NavigableMap.html#subMap%28K, K%29)(K fromKey,K toKey) Returns a view of the portion of this map whose keys range fromfromKey, inclusive, to toKey, exclusive. |
| SortedMap<K,V> | tailMap(K fromKey) Returns a view of the portion of this map whose keys are greater than or equal to fromKey. |
| NavigableMap<K,V> | [tailMap](../../java/util/NavigableMap.html#tailMap%28K, boolean%29)(K fromKey, boolean inclusive) Returns a view of the portion of this map whose keys are greater than (or equal to, if inclusive is true) fromKey. |
| Methods inherited from interface java.util.SortedMap |
|---|
| comparator, entrySet, firstKey, keySet, lastKey, values |
| Methods inherited from interface java.util.Map |
|---|
| clear, containsKey, containsValue, equals, get, hashCode, isEmpty, [put](../../java/util/Map.html#put%28K, V%29), putAll, remove, size |
| Method Detail |
|---|
lowerEntry
Map.Entry<K,V> lowerEntry(K key)
Returns a key-value mapping associated with the greatest key strictly less than the given key, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the greatest key less than key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
lowerKey
Returns the greatest key strictly less than the given key, ornull if there is no such key.
Parameters:
key - the key
Returns:
the greatest key less than key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
floorEntry
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, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the greatest key less than or equal tokey, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
floorKey
Returns the greatest key less than or equal to the given key, or null if there is no such key.
Parameters:
key - the key
Returns:
the greatest key less than or equal to key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
ceilingEntry
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, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the least key greater than or equal tokey, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
ceilingKey
Returns the least key greater than or equal to the given key, or null if there is no such key.
Parameters:
key - the key
Returns:
the least key greater than or equal to key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
higherEntry
Map.Entry<K,V> higherEntry(K key)
Returns a key-value mapping associated with the least key strictly greater than the given key, or null if there is no such key.
Parameters:
key - the key
Returns:
an entry with the least key greater than key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
higherKey
Returns the least key strictly greater than the given key, ornull if there is no such key.
Parameters:
key - the key
Returns:
the least key greater than key, or null if there is no such key
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if the specified key cannot be compared with the keys currently in the map
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if the specified key is null and this map does not permit null keys
firstEntry
Returns a key-value mapping associated with the least key in this map, or null if the map is empty.
Returns:
an entry with the least key, or null if this map is empty
lastEntry
Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
Returns:
an entry with the greatest key, or null if this map is empty
pollFirstEntry
Map.Entry<K,V> pollFirstEntry()
Removes and returns a key-value mapping associated with the least key in this map, or null if the map is empty.
Returns:
the removed first entry of this map, or null if this map is empty
pollLastEntry
Map.Entry<K,V> pollLastEntry()
Removes and returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.
Returns:
the removed last entry of this map, or null if this map is empty
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 own remove operation), the results of the iteration are undefined.
The returned map has an ordering equivalent toCollections.reverseOrder(comparator()). The expression m.descendingMap().descendingMap() returns a view of m essentially equivalent to m.
Returns:
a reverse order view of this map
navigableKeySet
NavigableSet<K> navigableKeySet()
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.
Returns:
a navigable set view of the keys in this map
descendingKeySet
NavigableSet<K> descendingKeySet()
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 navigable set view of the keys in this map
subMap
NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)
Returns a view of the portion of this map whose keys range fromfromKey to toKey. If fromKey andtoKey are equal, the returned map is empty unlessfromExclusive 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.
Parameters:
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
Returns:
a view of the portion of this map whose keys range fromfromKey to toKey
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if fromKey or toKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if fromKey is greater thantoKey; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range
headMap
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, 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.
Parameters:
toKey - high endpoint of the keys in the returned map
inclusive - true if 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 inclusive is true) toKey
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if toKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if this map itself has a restricted range, and toKey lies outside the bounds of the range
tailMap
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, 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.
Parameters:
fromKey - low endpoint of the keys in the returned map
inclusive - true if 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 inclusive is true) fromKey
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if fromKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if this map itself has a restricted range, and fromKey lies outside the bounds of the range
subMap
SortedMap<K,V> subMap(K fromKey, K toKey)
Returns a view of the portion of this map whose keys range fromfromKey, inclusive, to toKey, exclusive. (IffromKey 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).
Specified by:
[subMap](../../java/util/SortedMap.html#subMap%28K, K%29) in interface [SortedMap](../../java/util/SortedMap.html "interface in java.util")<[K](../../java/util/NavigableMap.html "type parameter in NavigableMap"),[V](../../java/util/NavigableMap.html "type parameter in NavigableMap")>
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 fromfromKey, inclusive, to toKey, exclusive
Throws:
[ClassCastException](../../java/lang/ClassCastException.html "class in java.lang") - if fromKey and toKey cannot be compared to one another using this map's comparator (or, if the map has no comparator, using natural ordering). Implementations may, but are not required to, throw this exception if fromKey or toKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if fromKey or toKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if fromKey is greater thantoKey; or if this map itself has a restricted range, and fromKey or toKey lies outside the bounds of the range
headMap
SortedMap<K,V> headMap(K toKey)
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).
Specified by:
[headMap](../../java/util/SortedMap.html#headMap%28K%29) in interface [SortedMap](../../java/util/SortedMap.html "interface in java.util")<[K](../../java/util/NavigableMap.html "type parameter in NavigableMap"),[V](../../java/util/NavigableMap.html "type parameter in NavigableMap")>
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](../../java/lang/ClassCastException.html "class in java.lang") - if toKey is not compatible with this map's comparator (or, if the map has no comparator, if toKey does not implement Comparable). Implementations may, but are not required to, throw this exception if toKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if toKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if this map itself has a restricted range, and toKey lies outside the bounds of the range
tailMap
SortedMap<K,V> tailMap(K fromKey)
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).
Specified by:
[tailMap](../../java/util/SortedMap.html#tailMap%28K%29) in interface [SortedMap](../../java/util/SortedMap.html "interface in java.util")<[K](../../java/util/NavigableMap.html "type parameter in NavigableMap"),[V](../../java/util/NavigableMap.html "type parameter in NavigableMap")>
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](../../java/lang/ClassCastException.html "class in java.lang") - if fromKey is not compatible with this map's comparator (or, if the map has no comparator, if fromKey does not implement Comparable). Implementations may, but are not required to, throw this exception if fromKey cannot be compared to keys currently in the map.
[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang") - if fromKey is null and this map does not permit null keys
[IllegalArgumentException](../../java/lang/IllegalArgumentException.html "class in java.lang") - if this map itself has a restricted range, and fromKey lies outside the bounds of the range
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