NavigableMap JDK 1.6)

Description

public interface NavigableMap

A SortedMap extended with navigation methods returning the closest matches for given search targets.

A SortedMap extended with navigation methods returning the closest matches for given search targets. Methods lowerEntry, 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, returning null if there is no such key. Similarly, methods lowerKey, floorKey, ceilingKey, and higherKey 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, and pollLastEntry 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), 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 overriden to return NavigableSet.

This interface is a member of the Java Collections Framework.

See also:

Methods

Hide/Show inherited methods

public 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.

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: an entry with the least key greater than or equal to {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public K ceilingKey ( K key)

Returns 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.
Returns: the least key greater than or equal to {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public NavigableSet< K> descendingKeySet ()

Returns a reverse order NavigableSet view of the keys contained in this map.

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

public NavigableMap< K, V> descendingMap ()

Returns a reverse order view of the mappings contained in this map.

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 reverse order view of this map

public Entry< K, V> firstEntry ()

Returns a key-value mapping associated with the least key in this map, or null if the map is empty.

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 {@code null} if this map is empty

public 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.

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: an entry with the greatest key less than or equal to {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public K floorKey ( K key)

Returns 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 greatest key less than or equal to {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public SortedMap< K, V> headMap ( K toKey) [Specified in SortedMap]

Returns a view of the portion of this map whose keys are strictly less than toKey.

public 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.

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.
Returns: a view of the portion of this map whose keys are less than (or equal to, if {@code inclusive} is true) {@code toKey}
Parameters:
- toKey - high endpoint of the keys in the returned map
- inclusive - {@code true} if the high endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code toKey} is not compatible with this map's comparator (or, if the map has no comparator, if {@code toKey} does not implement {@link Comparable}). Implementations may, but are not required to, throw this exception if {@code toKey} cannot be compared to keys currently in the map.
- NullPointerException - if {@code toKey} is null and this map does not permit null keys
- IllegalArgumentException - if this map itself has a restricted range, and {@code toKey} lies outside the bounds of the range

public 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.

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: an entry with the least key greater than {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public K higherKey ( K key)

Returns 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: the least key greater than {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public Entry< K, V> lastEntry ()

Returns a key-value mapping associated with the greatest key in this map, or null if the map is empty.

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 {@code null} if this map is empty

public 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.

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: an entry with the greatest key less than {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public K lowerKey ( K key)

Returns 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: the greatest key less than {@code key}, or {@code null} if there is no such key
Parameters:
- key - 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 does not permit null keys

public NavigableSet< K> navigableKeySet ()

Returns a NavigableSet view of the keys contained in this map.

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

public 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.

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 {@code null} if this map is empty

public 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.

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 {@code null} if this map is empty

public NavigableMap< K, V> subMap ( K fromKey, boolean fromInclusive, K toKey, boolean toInclusive)

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 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.
Returns: a view of the portion of this map whose keys range from {@code fromKey} to {@code toKey}
Parameters:
- fromKey - low endpoint of the keys in the returned map
- fromInclusive - {@code true} if the low endpoint is to be included in the returned view
- toKey - high endpoint of the keys in the returned map
- toInclusive - {@code true} if the high endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code fromKey} and {@code 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 {@code fromKey} or {@code toKey} cannot be compared to keys currently in the map.
- NullPointerException - if {@code fromKey} or {@code toKey} is null and this map does not permit null keys
- IllegalArgumentException - if {@code fromKey} is greater than {@code toKey}; or if this map itself has a restricted range, and {@code fromKey} or {@code toKey} lies outside the bounds of the range

public SortedMap< K, V> subMap ( K fromKey, K toKey) [Specified in SortedMap]

Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive.

public SortedMap< K, V> tailMap ( K fromKey) [Specified in SortedMap]

Returns a view of the portion of this map whose keys are greater than or equal to fromKey.

public 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.

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.
Returns: a view of the portion of this map whose keys are greater than (or equal to, if {@code inclusive} is true) {@code fromKey}
Parameters:
- fromKey - low endpoint of the keys in the returned map
- inclusive - {@code true} if the low endpoint is to be included in the returned view
Throws:
- ClassCastException - if {@code fromKey} is not compatible with this map's comparator (or, if the map has no comparator, if {@code fromKey} does not implement {@link Comparable}). Implementations may, but are not required to, throw this exception if {@code fromKey} cannot be compared to keys currently in the map.
- NullPointerException - if {@code fromKey} is null and this map does not permit null keys
- IllegalArgumentException - if this map itself has a restricted range, and {@code fromKey} lies outside the bounds of the range