--- jsr166/src/jsr166x/NavigableMap.java 2004/09/06 17:01:54 1.1
+++ jsr166/src/jsr166x/NavigableMap.java 2012/12/29 23:55:19 1.10
@@ -1,7 +1,7 @@
/*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
- * http://creativecommons.org/licenses/publicdomain
+ * http://creativecommons.org/publicdomain/zero/1.0/
*/
package jsr166x;
@@ -9,150 +9,255 @@ package jsr166x;
import java.util.*;
/**
- * A {@link SortedMap} extended with methods returning key-value pairs
- * holding the closest matches for given search targets. Methods
+ * A {@link SortedMap} extended with navigation methods returning the
+ * closest matches for given search targets. Methods
* lowerEntry, floorEntry, ceilingEntry,
- * and higherEntry return {@link Map.Entry} objects
+ * 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. These methods are designed
- * for locating, not traversing entries. To traverse, use view
- * iterators and/or submap. 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.
+ * 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.
*
- * Implementations of these 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.
+ *
A NavigableMap may be viewed and traversed in either
+ * ascending or descending key order. The Map methods
+ * keySet and entrySet return ascending views, and
+ * the additional methods descendingKeySet and
+ * descendingEntrySet return descending views. The
+ * performance of ascending traversals is likely to be faster than
+ * descending traversals. Notice that it is possible to perform
+ * subrannge traversals in either direction using SubMap.
+ *
+ *
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.
*
* @author Doug Lea
* @param the type of keys maintained by this map
- * @param the type of mapped values
+ * @param the type of mapped values
*/
public interface NavigableMap extends SortedMap {
/**
* 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 entry.
- *
- * @param key the key.
- * @return an Entry associated with ceiling of given key, or null
- * if there is no such Entry.
+ * greater than or equal to the given key, or null if there is
+ * no such entry.
+ *
+ * @param key the key
+ * @return an Entry associated with ceiling of given key, or null
+ * if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
+ * currently in the map
* @throws NullPointerException if key is null and this map
- * does not support null keys.
+ * does not support null keys
*/
public Map.Entry ceilingEntry(K key);
/**
+ * Returns least key greater than or equal to the given key, or
+ * null if there is no such key.
+ *
+ * @param key the key
+ * @return the ceiling key, or null
+ * if there is no such key
+ * @throws ClassCastException if key cannot be compared with the keys
+ * currently in the map
+ * @throws NullPointerException if key is null and this map
+ * does not support null keys
+ */
+ public K ceilingKey(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 entry.
- *
- * @param key the key.
+ * key strictly less than the given key, or null if there is no
+ * such entry.
+ *
+ * @param key the key
* @return an Entry with greatest key less than the given
- * key, or null if there is no such Entry.
+ * key, or null if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
+ * currently in the map
* @throws NullPointerException if key is null and this map
- * does not support null keys.
+ * does not support null keys
*/
public Map.Entry lowerEntry(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 entry.
- *
- * @param key the key.
- * @return an Entry associated with floor of given key, or null
- * if there is no such Entry.
+ * Returns the greatest key strictly less than the given key, or
+ * null if there is no such key.
+ *
+ * @param key the key
+ * @return the greatest key less than the given
+ * key, or null if there is no such key
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
+ * currently in the map
* @throws NullPointerException if key is null and this map
- * does not support null keys.
+ * does not support null keys
+ */
+ public K lowerKey(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 entry.
+ *
+ * @param key the key
+ * @return an Entry associated with floor of given key, or null
+ * if there is no such Entry
+ * @throws ClassCastException if key cannot be compared with the keys
+ * currently in the map
+ * @throws NullPointerException if key is null and this map
+ * does not support null keys
*/
public Map.Entry floorEntry(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 entry.
- *
- * @param key the key.
+ * Returns the greatest key
+ * less than or equal to the given key, or null if there
+ * is no such key.
+ *
+ * @param key the key
+ * @return the floor of given key, or null if there is no
+ * such key
+ * @throws ClassCastException if key cannot be compared with the keys
+ * currently in the map
+ * @throws NullPointerException if key is null and this map
+ * does not support null keys
+ */
+ public K floorKey(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 entry.
+ *
+ * @param key the key
* @return an Entry with least key greater than the given key, or
- * null if there is no such Entry.
+ * null if there is no such Entry
* @throws ClassCastException if key cannot be compared with the keys
- * currently in the map.
+ * currently in the map
* @throws NullPointerException if key is null and this map
- * does not support null keys.
+ * does not support null keys
*/
public Map.Entry higherEntry(K key);
/**
+ * Returns the least key strictly greater than the given key, or
+ * null if there is no such key.
+ *
+ * @param key the key
+ * @return the least key greater than the given key, or
+ * null if there is no such key
+ * @throws ClassCastException if key cannot be compared with the keys
+ * currently in the map
+ * @throws NullPointerException if key is null and this map
+ * does not support null keys
+ */
+ public K higherKey(K key);
+
+ /**
* Returns a key-value mapping associated with the least
- * key in this map, or null if the map is empty.
- *
- * @return an Entry with least key, or null
- * if the map is empty.
+ * key in this map, or null if the map is empty.
+ *
+ * @return an Entry with least key, or null
+ * if the map is empty
*/
public Map.Entry firstEntry();
/**
* Returns a key-value mapping associated with the greatest
- * key in this map, or null if the map is empty.
- *
- * @return an Entry with greatest key, or null
- * if the map is empty.
+ * key in this map, or null if the map is empty.
+ *
+ * @return an Entry with greatest key, or null
+ * if the map is empty
*/
public Map.Entry lastEntry();
/**
* Removes and returns a key-value mapping associated with
- * the least key in this map, or null if the map is empty.
- *
- * @return the removed first entry of this map, or null
- * if the map is empty.
+ * the least key in this map, or null if the map is empty.
+ *
+ * @return the removed first entry of this map, or null
+ * if the map is empty
*/
public Map.Entry pollFirstEntry();
/**
* Removes and returns a key-value mapping associated with
- * the greatest key in this map, or null if the map is empty.
- *
- * @return the removed last entry of this map, or null
- * if the map is empty.
+ * the greatest key in this map, or null if the map is empty.
+ *
+ * @return the removed last entry of this map, or null
+ * if the map is empty
*/
public Map.Entry pollLastEntry();
/**
+ * Returns a set view of the keys contained in this map, in
+ * descending 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),
+ * 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.
+ *
+ * @return a set view of the keys contained in this map
+ */
+ Set descendingKeySet();
+
+ /**
+ * Returns a set view of the mappings contained in this map, in
+ * descending key order. Each element in the returned set is a
+ * Map.Entry. 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.
+ *
+ * @return a set view of the mappings contained in this map
+ */
+ Set> descendingEntrySet();
+
+ /**
* 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 sorted map
* is empty.) The returned sorted map is backed by this map, so changes
* in the returned sorted map are reflected in this map, and vice-versa.
-
- * @param fromKey low endpoint (inclusive) of the subMap.
- * @param toKey high endpoint (exclusive) of the subMap.
+ *
+ * @param fromKey low endpoint (inclusive) of the subMap
+ * @param toKey high endpoint (exclusive) of the subMap
*
* @return a view of the portion of this map whose keys range from
- * fromKey, inclusive, to toKey, exclusive.
+ * fromKey, inclusive, to toKey, exclusive
*
* @throws 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).
+ * natural ordering)
* @throws IllegalArgumentException if fromKey is greater
- * than toKey.
+ * than toKey
* @throws NullPointerException if fromKey or
* toKey is null and this map does not support
- * null keys.
+ * null keys
*/
public NavigableMap subMap(K fromKey, K toKey);
@@ -160,16 +265,16 @@ public interface NavigableMap exten
* Returns a view of the portion of this map whose keys are strictly less
* than toKey. The returned sorted map is backed by this map, so
* changes in the returned sorted map are reflected in this map, and
- * vice-versa.
- * @param toKey high endpoint (exclusive) of the headMap.
+ * vice-versa.
+ * @param toKey high endpoint (exclusive) of the headMap
* @return a view of the portion of this map whose keys are strictly
- * less than toKey.
+ * less than toKey
*
* @throws ClassCastException if toKey is not compatible
* with this map's comparator (or, if the map has no comparator,
- * if toKey does not implement Comparable).
+ * if toKey does not implement Comparable)
* @throws NullPointerException if toKey is null
- * and this map does not support null keys.
+ * and this map does not support null keys
*/
public NavigableMap headMap(K toKey);
@@ -178,14 +283,14 @@ public interface NavigableMap exten
* greater than or equal to fromKey. The returned sorted
* map is backed by this map, so changes in the returned sorted
* map are reflected in this map, and vice-versa.
- * @param fromKey low endpoint (inclusive) of the tailMap.
+ * @param fromKey low endpoint (inclusive) of the tailMap
* @return a view of the portion of this map whose keys are greater
- * than or equal to fromKey.
+ * than or equal to fromKey
* @throws ClassCastException if fromKey is not compatible
* with this map's comparator (or, if the map has no comparator,
- * if fromKey does not implement Comparable).
+ * if fromKey does not implement Comparable)
* @throws NullPointerException if fromKey is null
- * and this map does not support null keys.
+ * and this map does not support null keys
*/
- public NavigableMap tailMap(K fromKey);
+ public NavigableMap tailMap(K fromKey);
}