java/util/NavigableMap.java

/*
 * 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
 */

package java.util;

/**
 * A {@link SortedMap} extended with navigation methods returning the
 * closest matches for given search targets. Methods
 * <tt>lowerEntry</tt>, <tt>floorEntry</tt>, <tt>ceilingEntry</tt>,
 * and <tt>higherEntry</tt> return <tt>Map.Entry</tt> objects
 * associated with keys respectively less than, less than or equal,
 * greater than or equal, and greater than a given key, returning
 * <tt>null</tt> if there is no such key.  Similarly, methods
 * <tt>lowerKey</tt>, <tt>floorKey</tt>, <tt>ceilingKey</tt>, and
 * <tt>higherKey</tt> return only the associated keys. All of these
 * methods are designed for locating, not traversing entries.
 *
 * <p>A <tt>NavigableMap</tt> may be viewed and traversed in either
 * ascending or descending key order.  The <tt>Map</tt> methods
 * <tt>keySet</tt> and <tt>entrySet</tt> return ascending views, and
 * the additional methods <tt>descendingKeySet</tt> and
 * <tt>descendingEntrySet</tt> return descending views. The
 * performance of ascending traversals is likely to be faster than
 * descending traversals.  Notice that it is possible to perform
 * subrange traversals in either direction using <tt>navigableSubMap</tt>.
 * Methods <tt>navigableSubMap</tt>, <tt>navigableHeadMap</tt>, and
 * <tt>navigableTailMap</tt> differ from the similarly named
 * <tt>SortedMap</tt> methods only in that the returned maps
 * are guaranteed to obey the <tt>NavigableMap</tt> interface.
 *
 * <p>This interface additionally defines methods <tt>firstEntry</tt>,
 * <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and
 * <tt>pollLastEntry</tt> that return and/or remove the least and
 * greatest mappings, if any exist, else returning <tt>null</tt>.
 *
 * <p> Implementations of entry-returning methods are expected to
 * return <tt>Map.Entry</tt> pairs representing snapshots of mappings
 * at the time they were produced, and thus generally do <em>not</em>
 * support the optional <tt>Entry.setValue</tt> method. Note however
 * that it is possible to change mappings in the associated map using
 * method <tt>put</tt>.
 *
 * @author Doug Lea
 * @param <K> the type of keys maintained by this map
 * @param <V> the type of mapped values
 * @since 1.6
 */
public interface NavigableMap<K,V> extends SortedMap<K,V> {
    /**
     * Returns a key-value mapping associated with the least key
     * greater than or equal to the given key, or <tt>null</tt> if there is
     * no such entry.
     *
     * @param key the key.
     * @return an Entry associated with ceiling of given key, or <tt>null</tt>
     * 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    Map.Entry<K,V> ceilingEntry(K key);

    /**
     * Returns least key greater than or equal to the given key, or
     * <tt>null</tt> if there is no such key.
     *
     * @param key the key.
     * @return the ceiling key, or <tt>null</tt>
     * 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    K ceilingKey(K key);

    /**
     * Returns a key-value mapping associated with the greatest
     * key strictly less than the given key, or <tt>null</tt> if there is no
     * such entry.
     *
     * @param key the key.
     * @return an Entry with greatest key less than the given
     * key, or <tt>null</tt> 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    Map.Entry<K,V> lowerEntry(K key);

    /**
     * Returns the greatest key strictly less than the given key, or
     * <tt>null</tt> if there is no such key.
     *
     * @param key the key.
     * @return the greatest key less than the given
     * key, or <tt>null</tt> 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    K lowerKey(K key);

    /**
     * Returns a key-value mapping associated with the greatest key
     * less than or equal to the given key, or <tt>null</tt> if there
     * is no such entry.
     *
     * @param key the key.
     * @return an Entry associated with floor of given key, or <tt>null</tt>
     * 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    Map.Entry<K,V> floorEntry(K key);

    /**
     * Returns the greatest key
     * less than or equal to the given key, or <tt>null</tt> if there
     * is no such key.
     *
     * @param key the key.
     * @return the floor of given key, or <tt>null</tt> 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    K floorKey(K key);

    /**
     * Returns a key-value mapping associated with the least key
     * strictly greater than the given key, or <tt>null</tt> if there
     * is no such entry.
     *
     * @param key the key.
     * @return an Entry with least key greater than the given key, or
     * <tt>null</tt> 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    Map.Entry<K,V> higherEntry(K key);

    /**
     * Returns the least key strictly greater than the given key, or
     * <tt>null</tt> if there is no such key.
     *
     * @param key the key.
     * @return the least key greater than the given key, or
     * <tt>null</tt> 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 <tt>null</tt> and this map
     * does not support <tt>null</tt> keys.
     */
    K higherKey(K key);

    /**
     * Returns a key-value mapping associated with the least
     * key in this map, or <tt>null</tt> if the map is empty.
     *
     * @return an Entry with least key, or <tt>null</tt>
     * if the map is empty.
     */
    Map.Entry<K,V> firstEntry();

    /**
     * Returns a key-value mapping associated with the greatest
     * key in this map, or <tt>null</tt> if the map is empty.
     *
     * @return an Entry with greatest key, or <tt>null</tt>
     * if the map is empty.
     */
    Map.Entry<K,V> lastEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the least key in this map, or <tt>null</tt> if the map is empty.
     *
     * @return the removed first entry of this map, or <tt>null</tt>
     * if the map is empty.
     */
    Map.Entry<K,V> pollFirstEntry();

    /**
     * Removes and returns a key-value mapping associated with
     * the greatest key in this map, or <tt>null</tt> if the map is empty.
     *
     * @return the removed last entry of this map, or <tt>null</tt>
     * if the map is empty.
     */
    Map.Entry<K,V> 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 <tt>remove</tt> operation),
     * the results of the iteration are undefined.  The set supports
     * element removal, which removes the corresponding mapping from
     * the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
     * <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt>
     * operations.  It does not support the add or <tt>addAll</tt>
     * operations.
     *
     * @return a set view of the keys contained in this map.
     */
    Set<K> descendingKeySet();

    /**
     * Returns a set view of the mappings contained in this map, in
     * descending key order.  Each element in the returned set is a
     * <tt>Map.Entry</tt>.  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 <tt>remove</tt> operation,
     * or through the <tt>setValue</tt> 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
     * <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
     * <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt>
     * operations.  It does not support the <tt>add</tt> or
     * <tt>addAll</tt> operations.
     *
     * @return a set view of the mappings contained in this map.
     */
    Set<Map.Entry<K, V>> descendingEntrySet();

    /**
     * Returns a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.  (If
     * <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned
     * navigable map is empty.)  The returned navigable map is backed
     * by this map, so changes in the returned navigable 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.
     *
     * @return a view of the portion of this map whose keys range from
     * <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
     *
     * @throws ClassCastException if <tt>fromKey</tt> and
     * <tt>toKey</tt> cannot be compared to one another using this
     * map's comparator (or, if the map has no comparator, using
     * natural ordering).
     * @throws IllegalArgumentException if <tt>fromKey</tt> is greater
     * than <tt>toKey</tt>.
     * @throws NullPointerException if <tt>fromKey</tt> or
     * <tt>toKey</tt> is <tt>null</tt> and this map does not support
     * <tt>null</tt> keys.
     */
    NavigableMap<K,V> navigableSubMap(K fromKey, K toKey);

    /**
     * Returns a view of the portion of this map whose keys are strictly less
     * than <tt>toKey</tt>.  The returned navigable map is backed by this map, so
     * changes in the returned navigable map are reflected in this map, and
     * 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 <tt>toKey</tt>.
     *
     * @throws ClassCastException if <tt>toKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    NavigableMap<K,V> navigableHeadMap(K toKey);

    /**
     * Returns a view of the portion of this map whose keys are
     * greater than or equal to <tt>fromKey</tt>.  The returned navigable
     * map is backed by this map, so changes in the returned navigable
     * map are reflected in this map, and vice-versa.
     * @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 <tt>fromKey</tt>.
     * @throws ClassCastException if <tt>fromKey</tt> is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
     * @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
     * and this map does not support <tt>null</tt> keys.
     */
    NavigableMap<K,V>  navigableTailMap(K fromKey);
}
Revision:	1.6
Committed:	Mon May 2 22:34:56 2005 UTC (19 years ago) by jsr166
Branch:	MAIN
Changes since 1.5:	+1 -0 lines
Log Message:	Add missing @since 1.6
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/licenses/publicdomain
5			*/
6
7			package java.util;
8
9			/**
10			* A {@link SortedMap} extended with navigation methods returning the
11			* closest matches for given search targets. Methods
12			* <tt>lowerEntry</tt>, <tt>floorEntry</tt>, <tt>ceilingEntry</tt>,
13			* and <tt>higherEntry</tt> return <tt>Map.Entry</tt> objects
14			* associated with keys respectively less than, less than or equal,
15			* greater than or equal, and greater than a given key, returning
16			* <tt>null</tt> if there is no such key. Similarly, methods
17			* <tt>lowerKey</tt>, <tt>floorKey</tt>, <tt>ceilingKey</tt>, and
18			* <tt>higherKey</tt> return only the associated keys. All of these
19			* methods are designed for locating, not traversing entries.
20			*
21			* <p>A <tt>NavigableMap</tt> may be viewed and traversed in either
22			* ascending or descending key order. The <tt>Map</tt> methods
23			* <tt>keySet</tt> and <tt>entrySet</tt> return ascending views, and
24			* the additional methods <tt>descendingKeySet</tt> and
25			* <tt>descendingEntrySet</tt> return descending views. The
26			* performance of ascending traversals is likely to be faster than
27			* descending traversals. Notice that it is possible to perform
28	dl	1.4	* subrange traversals in either direction using <tt>navigableSubMap</tt>.
29			* Methods <tt>navigableSubMap</tt>, <tt>navigableHeadMap</tt>, and
30			* <tt>navigableTailMap</tt> differ from the similarly named
31			* <tt>SortedMap</tt> methods only in that the returned maps
32			* are guaranteed to obey the <tt>NavigableMap</tt> interface.
33	jsr166	1.5	*
34	dl	1.1	* <p>This interface additionally defines methods <tt>firstEntry</tt>,
35			* <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and
36			* <tt>pollLastEntry</tt> that return and/or remove the least and
37			* greatest mappings, if any exist, else returning <tt>null</tt>.
38			*
39			* <p> Implementations of entry-returning methods are expected to
40			* return <tt>Map.Entry</tt> pairs representing snapshots of mappings
41			* at the time they were produced, and thus generally do <em>not</em>
42			* support the optional <tt>Entry.setValue</tt> method. Note however
43			* that it is possible to change mappings in the associated map using
44			* method <tt>put</tt>.
45			*
46			* @author Doug Lea
47			* @param <K> the type of keys maintained by this map
48	jsr166	1.5	* @param <V> the type of mapped values
49	jsr166	1.6	* @since 1.6
50	dl	1.1	*/
51			public interface NavigableMap<K,V> extends SortedMap<K,V> {
52			/**
53			* Returns a key-value mapping associated with the least key
54			* greater than or equal to the given key, or <tt>null</tt> if there is
55	jsr166	1.5	* no such entry.
56			*
57	dl	1.1	* @param key the key.
58			* @return an Entry associated with ceiling of given key, or <tt>null</tt>
59			* if there is no such Entry.
60			* @throws ClassCastException if key cannot be compared with the keys
61			* currently in the map.
62			* @throws NullPointerException if key is <tt>null</tt> and this map
63			* does not support <tt>null</tt> keys.
64			*/
65	dl	1.3	Map.Entry<K,V> ceilingEntry(K key);
66	dl	1.1
67			/**
68			* Returns least key greater than or equal to the given key, or
69			* <tt>null</tt> if there is no such key.
70	jsr166	1.5	*
71	dl	1.1	* @param key the key.
72			* @return the ceiling key, or <tt>null</tt>
73			* if there is no such key.
74			* @throws ClassCastException if key cannot be compared with the keys
75			* currently in the map.
76			* @throws NullPointerException if key is <tt>null</tt> and this map
77			* does not support <tt>null</tt> keys.
78			*/
79	dl	1.3	K ceilingKey(K key);
80	dl	1.1
81			/**
82			* Returns a key-value mapping associated with the greatest
83			* key strictly less than the given key, or <tt>null</tt> if there is no
84	jsr166	1.5	* such entry.
85			*
86	dl	1.1	* @param key the key.
87			* @return an Entry with greatest key less than the given
88			* key, or <tt>null</tt> if there is no such Entry.
89			* @throws ClassCastException if key cannot be compared with the keys
90			* currently in the map.
91			* @throws NullPointerException if key is <tt>null</tt> and this map
92			* does not support <tt>null</tt> keys.
93			*/
94	dl	1.3	Map.Entry<K,V> lowerEntry(K key);
95	dl	1.1
96			/**
97			* Returns the greatest key strictly less than the given key, or
98			* <tt>null</tt> if there is no such key.
99	jsr166	1.5	*
100	dl	1.1	* @param key the key.
101			* @return the greatest key less than the given
102			* key, or <tt>null</tt> if there is no such key.
103			* @throws ClassCastException if key cannot be compared with the keys
104			* currently in the map.
105			* @throws NullPointerException if key is <tt>null</tt> and this map
106			* does not support <tt>null</tt> keys.
107			*/
108	dl	1.3	K lowerKey(K key);
109	dl	1.1
110			/**
111			* Returns a key-value mapping associated with the greatest key
112			* less than or equal to the given key, or <tt>null</tt> if there
113			* is no such entry.
114	jsr166	1.5	*
115	dl	1.1	* @param key the key.
116			* @return an Entry associated with floor of given key, or <tt>null</tt>
117			* if there is no such Entry.
118			* @throws ClassCastException if key cannot be compared with the keys
119			* currently in the map.
120			* @throws NullPointerException if key is <tt>null</tt> and this map
121			* does not support <tt>null</tt> keys.
122			*/
123	dl	1.3	Map.Entry<K,V> floorEntry(K key);
124	dl	1.1
125			/**
126			* Returns the greatest key
127			* less than or equal to the given key, or <tt>null</tt> if there
128			* is no such key.
129	jsr166	1.5	*
130	dl	1.1	* @param key the key.
131			* @return the floor of given key, or <tt>null</tt> if there is no
132			* such key.
133			* @throws ClassCastException if key cannot be compared with the keys
134			* currently in the map.
135			* @throws NullPointerException if key is <tt>null</tt> and this map
136			* does not support <tt>null</tt> keys.
137			*/
138	dl	1.3	K floorKey(K key);
139	dl	1.1
140			/**
141			* Returns a key-value mapping associated with the least key
142			* strictly greater than the given key, or <tt>null</tt> if there
143			* is no such entry.
144	jsr166	1.5	*
145	dl	1.1	* @param key the key.
146			* @return an Entry with least key greater than the given key, or
147			* <tt>null</tt> if there is no such Entry.
148			* @throws ClassCastException if key cannot be compared with the keys
149			* currently in the map.
150			* @throws NullPointerException if key is <tt>null</tt> and this map
151			* does not support <tt>null</tt> keys.
152			*/
153	dl	1.3	Map.Entry<K,V> higherEntry(K key);
154	dl	1.1
155			/**
156			* Returns the least key strictly greater than the given key, or
157			* <tt>null</tt> if there is no such key.
158	jsr166	1.5	*
159	dl	1.1	* @param key the key.
160			* @return the least key greater than the given key, or
161			* <tt>null</tt> if there is no such key.
162			* @throws ClassCastException if key cannot be compared with the keys
163			* currently in the map.
164			* @throws NullPointerException if key is <tt>null</tt> and this map
165			* does not support <tt>null</tt> keys.
166			*/
167	dl	1.3	K higherKey(K key);
168	dl	1.1
169			/**
170			* Returns a key-value mapping associated with the least
171			* key in this map, or <tt>null</tt> if the map is empty.
172	jsr166	1.5	*
173			* @return an Entry with least key, or <tt>null</tt>
174	dl	1.1	* if the map is empty.
175			*/
176	dl	1.3	Map.Entry<K,V> firstEntry();
177	dl	1.1
178			/**
179			* Returns a key-value mapping associated with the greatest
180			* key in this map, or <tt>null</tt> if the map is empty.
181	jsr166	1.5	*
182	dl	1.1	* @return an Entry with greatest key, or <tt>null</tt>
183			* if the map is empty.
184			*/
185	dl	1.3	Map.Entry<K,V> lastEntry();
186	dl	1.1
187			/**
188			* Removes and returns a key-value mapping associated with
189			* the least key in this map, or <tt>null</tt> if the map is empty.
190	jsr166	1.5	*
191	dl	1.1	* @return the removed first entry of this map, or <tt>null</tt>
192			* if the map is empty.
193			*/
194	dl	1.3	Map.Entry<K,V> pollFirstEntry();
195	dl	1.1
196			/**
197			* Removes and returns a key-value mapping associated with
198			* the greatest key in this map, or <tt>null</tt> if the map is empty.
199	jsr166	1.5	*
200	dl	1.1	* @return the removed last entry of this map, or <tt>null</tt>
201			* if the map is empty.
202			*/
203	dl	1.3	Map.Entry<K,V> pollLastEntry();
204	dl	1.1
205			/**
206			* Returns a set view of the keys contained in this map, in
207			* descending key order. The set is backed by the map, so changes
208			* to the map are reflected in the set, and vice-versa. If the
209			* map is modified while an iteration over the set is in progress
210			* (except through the iterator's own <tt>remove</tt> operation),
211			* the results of the iteration are undefined. The set supports
212			* element removal, which removes the corresponding mapping from
213			* the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
214			* <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt>
215			* operations. It does not support the add or <tt>addAll</tt>
216			* operations.
217			*
218			* @return a set view of the keys contained in this map.
219			*/
220			Set<K> descendingKeySet();
221
222			/**
223			* Returns a set view of the mappings contained in this map, in
224			* descending key order. Each element in the returned set is a
225			* <tt>Map.Entry</tt>. The set is backed by the map, so changes to
226			* the map are reflected in the set, and vice-versa. If the map
227			* is modified while an iteration over the set is in progress
228			* (except through the iterator's own <tt>remove</tt> operation,
229			* or through the <tt>setValue</tt> operation on a map entry
230			* returned by the iterator) the results of the iteration are
231			* undefined. The set supports element removal, which removes the
232			* corresponding mapping from the map, via the
233			* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
234			* <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt>
235			* operations. It does not support the <tt>add</tt> or
236			* <tt>addAll</tt> operations.
237			*
238			* @return a set view of the mappings contained in this map.
239			*/
240			Set<Map.Entry<K, V>> descendingEntrySet();
241
242			/**
243			* Returns a view of the portion of this map whose keys range from
244			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If
245	dl	1.3	* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned
246			* navigable map is empty.) The returned navigable map is backed
247			* by this map, so changes in the returned navigable map are
248	jsr166	1.5	* reflected in this map, and vice-versa.
249	dl	1.3	*
250	dl	1.1	* @param fromKey low endpoint (inclusive) of the subMap.
251			* @param toKey high endpoint (exclusive) of the subMap.
252			*
253			* @return a view of the portion of this map whose keys range from
254			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
255			*
256			* @throws ClassCastException if <tt>fromKey</tt> and
257			* <tt>toKey</tt> cannot be compared to one another using this
258			* map's comparator (or, if the map has no comparator, using
259			* natural ordering).
260			* @throws IllegalArgumentException if <tt>fromKey</tt> is greater
261			* than <tt>toKey</tt>.
262			* @throws NullPointerException if <tt>fromKey</tt> or
263			* <tt>toKey</tt> is <tt>null</tt> and this map does not support
264			* <tt>null</tt> keys.
265			*/
266	dl	1.3	NavigableMap<K,V> navigableSubMap(K fromKey, K toKey);
267	dl	1.1
268			/**
269			* Returns a view of the portion of this map whose keys are strictly less
270	dl	1.3	* than <tt>toKey</tt>. The returned navigable map is backed by this map, so
271			* changes in the returned navigable map are reflected in this map, and
272	jsr166	1.5	* vice-versa.
273	dl	1.1	* @param toKey high endpoint (exclusive) of the headMap.
274			* @return a view of the portion of this map whose keys are strictly
275			* less than <tt>toKey</tt>.
276			*
277			* @throws ClassCastException if <tt>toKey</tt> is not compatible
278			* with this map's comparator (or, if the map has no comparator,
279			* if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
280			* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
281			* and this map does not support <tt>null</tt> keys.
282			*/
283	dl	1.3	NavigableMap<K,V> navigableHeadMap(K toKey);
284	dl	1.1
285			/**
286			* Returns a view of the portion of this map whose keys are
287	dl	1.3	* greater than or equal to <tt>fromKey</tt>. The returned navigable
288			* map is backed by this map, so changes in the returned navigable
289	dl	1.1	* map are reflected in this map, and vice-versa.
290			* @param fromKey low endpoint (inclusive) of the tailMap.
291			* @return a view of the portion of this map whose keys are greater
292			* than or equal to <tt>fromKey</tt>.
293			* @throws ClassCastException if <tt>fromKey</tt> is not compatible
294			* with this map's comparator (or, if the map has no comparator,
295			* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
296			* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
297			* and this map does not support <tt>null</tt> keys.
298			*/
299	dl	1.3	NavigableMap<K,V> navigableTailMap(K fromKey);
300	dl	1.1	}