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
 */
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:	1.5
Committed:	Mon May 2 18:38:53 2005 UTC (19 years ago) by jsr166
Branch:	MAIN
Changes since 1.4:	+19 -19 lines
Log Message:	remove trailing whitespace
#	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	dl	1.1	*/
50			public interface NavigableMap<K,V> extends SortedMap<K,V> {
51			/**
52			* Returns a key-value mapping associated with the least key
53			* greater than or equal to the given key, or <tt>null</tt> if there is
54	jsr166	1.5	* no such entry.
55			*
56	dl	1.1	* @param key the key.
57			* @return an Entry associated with ceiling of given key, or <tt>null</tt>
58			* if there is no such Entry.
59			* @throws ClassCastException if key cannot be compared with the keys
60			* currently in the map.
61			* @throws NullPointerException if key is <tt>null</tt> and this map
62			* does not support <tt>null</tt> keys.
63			*/
64	dl	1.3	Map.Entry<K,V> ceilingEntry(K key);
65	dl	1.1
66			/**
67			* Returns least key greater than or equal to the given key, or
68			* <tt>null</tt> if there is no such key.
69	jsr166	1.5	*
70	dl	1.1	* @param key the key.
71			* @return the ceiling key, or <tt>null</tt>
72			* if there is no such key.
73			* @throws ClassCastException if key cannot be compared with the keys
74			* currently in the map.
75			* @throws NullPointerException if key is <tt>null</tt> and this map
76			* does not support <tt>null</tt> keys.
77			*/
78	dl	1.3	K ceilingKey(K key);
79	dl	1.1
80			/**
81			* Returns a key-value mapping associated with the greatest
82			* key strictly less than the given key, or <tt>null</tt> if there is no
83	jsr166	1.5	* such entry.
84			*
85	dl	1.1	* @param key the key.
86			* @return an Entry with greatest key less than the given
87			* key, or <tt>null</tt> if there is no such Entry.
88			* @throws ClassCastException if key cannot be compared with the keys
89			* currently in the map.
90			* @throws NullPointerException if key is <tt>null</tt> and this map
91			* does not support <tt>null</tt> keys.
92			*/
93	dl	1.3	Map.Entry<K,V> lowerEntry(K key);
94	dl	1.1
95			/**
96			* Returns the greatest key strictly less than the given key, or
97			* <tt>null</tt> if there is no such key.
98	jsr166	1.5	*
99	dl	1.1	* @param key the key.
100			* @return the greatest key less than the given
101			* key, or <tt>null</tt> if there is no such key.
102			* @throws ClassCastException if key cannot be compared with the keys
103			* currently in the map.
104			* @throws NullPointerException if key is <tt>null</tt> and this map
105			* does not support <tt>null</tt> keys.
106			*/
107	dl	1.3	K lowerKey(K key);
108	dl	1.1
109			/**
110			* Returns a key-value mapping associated with the greatest key
111			* less than or equal to the given key, or <tt>null</tt> if there
112			* is no such entry.
113	jsr166	1.5	*
114	dl	1.1	* @param key the key.
115			* @return an Entry associated with floor of given key, or <tt>null</tt>
116			* if there is no such Entry.
117			* @throws ClassCastException if key cannot be compared with the keys
118			* currently in the map.
119			* @throws NullPointerException if key is <tt>null</tt> and this map
120			* does not support <tt>null</tt> keys.
121			*/
122	dl	1.3	Map.Entry<K,V> floorEntry(K key);
123	dl	1.1
124			/**
125			* Returns the greatest key
126			* less than or equal to the given key, or <tt>null</tt> if there
127			* is no such key.
128	jsr166	1.5	*
129	dl	1.1	* @param key the key.
130			* @return the floor of given key, or <tt>null</tt> if there is no
131			* such key.
132			* @throws ClassCastException if key cannot be compared with the keys
133			* currently in the map.
134			* @throws NullPointerException if key is <tt>null</tt> and this map
135			* does not support <tt>null</tt> keys.
136			*/
137	dl	1.3	K floorKey(K key);
138	dl	1.1
139			/**
140			* Returns a key-value mapping associated with the least key
141			* strictly greater than the given key, or <tt>null</tt> if there
142			* is no such entry.
143	jsr166	1.5	*
144	dl	1.1	* @param key the key.
145			* @return an Entry with least key greater than the given key, or
146			* <tt>null</tt> if there is no such Entry.
147			* @throws ClassCastException if key cannot be compared with the keys
148			* currently in the map.
149			* @throws NullPointerException if key is <tt>null</tt> and this map
150			* does not support <tt>null</tt> keys.
151			*/
152	dl	1.3	Map.Entry<K,V> higherEntry(K key);
153	dl	1.1
154			/**
155			* Returns the least key strictly greater than the given key, or
156			* <tt>null</tt> if there is no such key.
157	jsr166	1.5	*
158	dl	1.1	* @param key the key.
159			* @return the least key greater than the given key, or
160			* <tt>null</tt> if there is no such key.
161			* @throws ClassCastException if key cannot be compared with the keys
162			* currently in the map.
163			* @throws NullPointerException if key is <tt>null</tt> and this map
164			* does not support <tt>null</tt> keys.
165			*/
166	dl	1.3	K higherKey(K key);
167	dl	1.1
168			/**
169			* Returns a key-value mapping associated with the least
170			* key in this map, or <tt>null</tt> if the map is empty.
171	jsr166	1.5	*
172			* @return an Entry with least key, or <tt>null</tt>
173	dl	1.1	* if the map is empty.
174			*/
175	dl	1.3	Map.Entry<K,V> firstEntry();
176	dl	1.1
177			/**
178			* Returns a key-value mapping associated with the greatest
179			* key in this map, or <tt>null</tt> if the map is empty.
180	jsr166	1.5	*
181	dl	1.1	* @return an Entry with greatest key, or <tt>null</tt>
182			* if the map is empty.
183			*/
184	dl	1.3	Map.Entry<K,V> lastEntry();
185	dl	1.1
186			/**
187			* Removes and returns a key-value mapping associated with
188			* the least key in this map, or <tt>null</tt> if the map is empty.
189	jsr166	1.5	*
190	dl	1.1	* @return the removed first entry of this map, or <tt>null</tt>
191			* if the map is empty.
192			*/
193	dl	1.3	Map.Entry<K,V> pollFirstEntry();
194	dl	1.1
195			/**
196			* Removes and returns a key-value mapping associated with
197			* the greatest key in this map, or <tt>null</tt> if the map is empty.
198	jsr166	1.5	*
199	dl	1.1	* @return the removed last entry of this map, or <tt>null</tt>
200			* if the map is empty.
201			*/
202	dl	1.3	Map.Entry<K,V> pollLastEntry();
203	dl	1.1
204			/**
205			* Returns a set view of the keys contained in this map, in
206			* descending key order. The set is backed by the map, so changes
207			* to the map are reflected in the set, and vice-versa. If the
208			* map is modified while an iteration over the set is in progress
209			* (except through the iterator's own <tt>remove</tt> operation),
210			* the results of the iteration are undefined. The set supports
211			* element removal, which removes the corresponding mapping from
212			* the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
213			* <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt>
214			* operations. It does not support the add or <tt>addAll</tt>
215			* operations.
216			*
217			* @return a set view of the keys contained in this map.
218			*/
219			Set<K> descendingKeySet();
220
221			/**
222			* Returns a set view of the mappings contained in this map, in
223			* descending key order. Each element in the returned set is a
224			* <tt>Map.Entry</tt>. The set is backed by the map, so changes to
225			* the map are reflected in the set, and vice-versa. If the map
226			* is modified while an iteration over the set is in progress
227			* (except through the iterator's own <tt>remove</tt> operation,
228			* or through the <tt>setValue</tt> operation on a map entry
229			* returned by the iterator) the results of the iteration are
230			* undefined. The set supports element removal, which removes the
231			* corresponding mapping from the map, via the
232			* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
233			* <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt>
234			* operations. It does not support the <tt>add</tt> or
235			* <tt>addAll</tt> operations.
236			*
237			* @return a set view of the mappings contained in this map.
238			*/
239			Set<Map.Entry<K, V>> descendingEntrySet();
240
241			/**
242			* Returns a view of the portion of this map whose keys range from
243			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If
244	dl	1.3	* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned
245			* navigable map is empty.) The returned navigable map is backed
246			* by this map, so changes in the returned navigable map are
247	jsr166	1.5	* reflected in this map, and vice-versa.
248	dl	1.3	*
249	dl	1.1	* @param fromKey low endpoint (inclusive) of the subMap.
250			* @param toKey high endpoint (exclusive) of the subMap.
251			*
252			* @return a view of the portion of this map whose keys range from
253			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
254			*
255			* @throws ClassCastException if <tt>fromKey</tt> and
256			* <tt>toKey</tt> cannot be compared to one another using this
257			* map's comparator (or, if the map has no comparator, using
258			* natural ordering).
259			* @throws IllegalArgumentException if <tt>fromKey</tt> is greater
260			* than <tt>toKey</tt>.
261			* @throws NullPointerException if <tt>fromKey</tt> or
262			* <tt>toKey</tt> is <tt>null</tt> and this map does not support
263			* <tt>null</tt> keys.
264			*/
265	dl	1.3	NavigableMap<K,V> navigableSubMap(K fromKey, K toKey);
266	dl	1.1
267			/**
268			* Returns a view of the portion of this map whose keys are strictly less
269	dl	1.3	* than <tt>toKey</tt>. The returned navigable map is backed by this map, so
270			* changes in the returned navigable map are reflected in this map, and
271	jsr166	1.5	* vice-versa.
272	dl	1.1	* @param toKey high endpoint (exclusive) of the headMap.
273			* @return a view of the portion of this map whose keys are strictly
274			* less than <tt>toKey</tt>.
275			*
276			* @throws ClassCastException if <tt>toKey</tt> is not compatible
277			* with this map's comparator (or, if the map has no comparator,
278			* if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
279			* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
280			* and this map does not support <tt>null</tt> keys.
281			*/
282	dl	1.3	NavigableMap<K,V> navigableHeadMap(K toKey);
283	dl	1.1
284			/**
285			* Returns a view of the portion of this map whose keys are
286	dl	1.3	* greater than or equal to <tt>fromKey</tt>. The returned navigable
287			* map is backed by this map, so changes in the returned navigable
288	dl	1.1	* map are reflected in this map, and vice-versa.
289			* @param fromKey low endpoint (inclusive) of the tailMap.
290			* @return a view of the portion of this map whose keys are greater
291			* than or equal to <tt>fromKey</tt>.
292			* @throws ClassCastException if <tt>fromKey</tt> is not compatible
293			* with this map's comparator (or, if the map has no comparator,
294			* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
295			* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
296			* and this map does not support <tt>null</tt> keys.
297			*/
298	dl	1.3	NavigableMap<K,V> navigableTailMap(K fromKey);
299	dl	1.1	}