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>SubMap</tt>.
 * 
 * <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. Note: This
     * method differs from <tt>SortedMap.subMap</tt> only
     * in that the returned map is guaranteed to support the
     * <tt>NavigableMap</tt> interface.
     *
     * @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:	1.3
Committed:	Tue Mar 22 01:30:10 2005 UTC (19 years, 1 month ago) by dl
Branch:	MAIN
Changes since 1.2:	+27 -23 lines
Log Message:	NavigableMap.subMap -> NavigableMap.navigableSubMap, and associated changes
#	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	1.2	* subrange traversals in either direction using <tt>SubMap</tt>.
29	dl	1.1	*
30			* <p>This interface additionally defines methods <tt>firstEntry</tt>,
31			* <tt>pollFirstEntry</tt>, <tt>lastEntry</tt>, and
32			* <tt>pollLastEntry</tt> that return and/or remove the least and
33			* greatest mappings, if any exist, else returning <tt>null</tt>.
34			*
35			* <p> Implementations of entry-returning methods are expected to
36			* return <tt>Map.Entry</tt> pairs representing snapshots of mappings
37			* at the time they were produced, and thus generally do <em>not</em>
38			* support the optional <tt>Entry.setValue</tt> method. Note however
39			* that it is possible to change mappings in the associated map using
40			* method <tt>put</tt>.
41			*
42			* @author Doug Lea
43			* @param <K> the type of keys maintained by this map
44			* @param <V> the type of mapped values
45			*/
46			public interface NavigableMap<K,V> extends SortedMap<K,V> {
47			/**
48			* Returns a key-value mapping associated with the least key
49			* greater than or equal to the given key, or <tt>null</tt> if there is
50			* no such entry.
51			*
52			* @param key the key.
53			* @return an Entry associated with ceiling of given key, or <tt>null</tt>
54			* if there is no such Entry.
55			* @throws ClassCastException if key cannot be compared with the keys
56			* currently in the map.
57			* @throws NullPointerException if key is <tt>null</tt> and this map
58			* does not support <tt>null</tt> keys.
59			*/
60	dl	1.3	Map.Entry<K,V> ceilingEntry(K key);
61	dl	1.1
62			/**
63			* Returns least key greater than or equal to the given key, or
64			* <tt>null</tt> if there is no such key.
65			*
66			* @param key the key.
67			* @return the ceiling key, or <tt>null</tt>
68			* if there is no such key.
69			* @throws ClassCastException if key cannot be compared with the keys
70			* currently in the map.
71			* @throws NullPointerException if key is <tt>null</tt> and this map
72			* does not support <tt>null</tt> keys.
73			*/
74	dl	1.3	K ceilingKey(K key);
75	dl	1.1
76			/**
77			* Returns a key-value mapping associated with the greatest
78			* key strictly less than the given key, or <tt>null</tt> if there is no
79			* such entry.
80			*
81			* @param key the key.
82			* @return an Entry with greatest key less than the given
83			* key, or <tt>null</tt> if there is no such Entry.
84			* @throws ClassCastException if key cannot be compared with the keys
85			* currently in the map.
86			* @throws NullPointerException if key is <tt>null</tt> and this map
87			* does not support <tt>null</tt> keys.
88			*/
89	dl	1.3	Map.Entry<K,V> lowerEntry(K key);
90	dl	1.1
91			/**
92			* Returns the greatest key strictly less than the given key, or
93			* <tt>null</tt> if there is no such key.
94			*
95			* @param key the key.
96			* @return the greatest key less than the given
97			* key, or <tt>null</tt> if there is no such key.
98			* @throws ClassCastException if key cannot be compared with the keys
99			* currently in the map.
100			* @throws NullPointerException if key is <tt>null</tt> and this map
101			* does not support <tt>null</tt> keys.
102			*/
103	dl	1.3	K lowerKey(K key);
104	dl	1.1
105			/**
106			* Returns a key-value mapping associated with the greatest key
107			* less than or equal to the given key, or <tt>null</tt> if there
108			* is no such entry.
109			*
110			* @param key the key.
111			* @return an Entry associated with floor of given key, or <tt>null</tt>
112			* if there is no such Entry.
113			* @throws ClassCastException if key cannot be compared with the keys
114			* currently in the map.
115			* @throws NullPointerException if key is <tt>null</tt> and this map
116			* does not support <tt>null</tt> keys.
117			*/
118	dl	1.3	Map.Entry<K,V> floorEntry(K key);
119	dl	1.1
120			/**
121			* Returns the greatest key
122			* less than or equal to the given key, or <tt>null</tt> if there
123			* is no such key.
124			*
125			* @param key the key.
126			* @return the floor of given key, or <tt>null</tt> if there is no
127			* such key.
128			* @throws ClassCastException if key cannot be compared with the keys
129			* currently in the map.
130			* @throws NullPointerException if key is <tt>null</tt> and this map
131			* does not support <tt>null</tt> keys.
132			*/
133	dl	1.3	K floorKey(K key);
134	dl	1.1
135			/**
136			* Returns a key-value mapping associated with the least key
137			* strictly greater than the given key, or <tt>null</tt> if there
138			* is no such entry.
139			*
140			* @param key the key.
141			* @return an Entry with least key greater than the given key, or
142			* <tt>null</tt> if there is no such Entry.
143			* @throws ClassCastException if key cannot be compared with the keys
144			* currently in the map.
145			* @throws NullPointerException if key is <tt>null</tt> and this map
146			* does not support <tt>null</tt> keys.
147			*/
148	dl	1.3	Map.Entry<K,V> higherEntry(K key);
149	dl	1.1
150			/**
151			* Returns the least key strictly greater than the given key, or
152			* <tt>null</tt> if there is no such key.
153			*
154			* @param key the key.
155			* @return the least key greater than the given key, or
156			* <tt>null</tt> if there is no such key.
157			* @throws ClassCastException if key cannot be compared with the keys
158			* currently in the map.
159			* @throws NullPointerException if key is <tt>null</tt> and this map
160			* does not support <tt>null</tt> keys.
161			*/
162	dl	1.3	K higherKey(K key);
163	dl	1.1
164			/**
165			* Returns a key-value mapping associated with the least
166			* key in this map, or <tt>null</tt> if the map is empty.
167			*
168			* @return an Entry with least key, or <tt>null</tt>
169			* if the map is empty.
170			*/
171	dl	1.3	Map.Entry<K,V> firstEntry();
172	dl	1.1
173			/**
174			* Returns a key-value mapping associated with the greatest
175			* key in this map, or <tt>null</tt> if the map is empty.
176			*
177			* @return an Entry with greatest key, or <tt>null</tt>
178			* if the map is empty.
179			*/
180	dl	1.3	Map.Entry<K,V> lastEntry();
181	dl	1.1
182			/**
183			* Removes and returns a key-value mapping associated with
184			* the least key in this map, or <tt>null</tt> if the map is empty.
185			*
186			* @return the removed first entry of this map, or <tt>null</tt>
187			* if the map is empty.
188			*/
189	dl	1.3	Map.Entry<K,V> pollFirstEntry();
190	dl	1.1
191			/**
192			* Removes and returns a key-value mapping associated with
193			* the greatest key in this map, or <tt>null</tt> if the map is empty.
194			*
195			* @return the removed last entry of this map, or <tt>null</tt>
196			* if the map is empty.
197			*/
198	dl	1.3	Map.Entry<K,V> pollLastEntry();
199	dl	1.1
200			/**
201			* Returns a set view of the keys contained in this map, in
202			* descending key order. The set is backed by the map, so changes
203			* to the map are reflected in the set, and vice-versa. If the
204			* map is modified while an iteration over the set is in progress
205			* (except through the iterator's own <tt>remove</tt> operation),
206			* the results of the iteration are undefined. The set supports
207			* element removal, which removes the corresponding mapping from
208			* the map, via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
209			* <tt>removeAll</tt> <tt>retainAll</tt>, and <tt>clear</tt>
210			* operations. It does not support the add or <tt>addAll</tt>
211			* operations.
212			*
213			* @return a set view of the keys contained in this map.
214			*/
215			Set<K> descendingKeySet();
216
217			/**
218			* Returns a set view of the mappings contained in this map, in
219			* descending key order. Each element in the returned set is a
220			* <tt>Map.Entry</tt>. The set is backed by the map, so changes to
221			* the map are reflected in the set, and vice-versa. If the map
222			* is modified while an iteration over the set is in progress
223			* (except through the iterator's own <tt>remove</tt> operation,
224			* or through the <tt>setValue</tt> operation on a map entry
225			* returned by the iterator) the results of the iteration are
226			* undefined. The set supports element removal, which removes the
227			* corresponding mapping from the map, via the
228			* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
229			* <tt>removeAll</tt>, <tt>retainAll</tt> and <tt>clear</tt>
230			* operations. It does not support the <tt>add</tt> or
231			* <tt>addAll</tt> operations.
232			*
233			* @return a set view of the mappings contained in this map.
234			*/
235			Set<Map.Entry<K, V>> descendingEntrySet();
236
237			/**
238			* Returns a view of the portion of this map whose keys range from
239			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive. (If
240	dl	1.3	* <tt>fromKey</tt> and <tt>toKey</tt> are equal, the returned
241			* navigable map is empty.) The returned navigable map is backed
242			* by this map, so changes in the returned navigable map are
243			* reflected in this map, and vice-versa. Note: This
244			* method differs from <tt>SortedMap.subMap</tt> only
245			* in that the returned map is guaranteed to support the
246			* <tt>NavigableMap</tt> interface.
247			*
248	dl	1.1	* @param fromKey low endpoint (inclusive) of the subMap.
249			* @param toKey high endpoint (exclusive) of the subMap.
250			*
251			* @return a view of the portion of this map whose keys range from
252			* <tt>fromKey</tt>, inclusive, to <tt>toKey</tt>, exclusive.
253			*
254			* @throws ClassCastException if <tt>fromKey</tt> and
255			* <tt>toKey</tt> cannot be compared to one another using this
256			* map's comparator (or, if the map has no comparator, using
257			* natural ordering).
258			* @throws IllegalArgumentException if <tt>fromKey</tt> is greater
259			* than <tt>toKey</tt>.
260			* @throws NullPointerException if <tt>fromKey</tt> or
261			* <tt>toKey</tt> is <tt>null</tt> and this map does not support
262			* <tt>null</tt> keys.
263			*/
264	dl	1.3	NavigableMap<K,V> navigableSubMap(K fromKey, K toKey);
265	dl	1.1
266			/**
267			* Returns a view of the portion of this map whose keys are strictly less
268	dl	1.3	* than <tt>toKey</tt>. The returned navigable map is backed by this map, so
269			* changes in the returned navigable map are reflected in this map, and
270	dl	1.1	* vice-versa.
271			* @param toKey high endpoint (exclusive) of the headMap.
272			* @return a view of the portion of this map whose keys are strictly
273			* less than <tt>toKey</tt>.
274			*
275			* @throws ClassCastException if <tt>toKey</tt> is not compatible
276			* with this map's comparator (or, if the map has no comparator,
277			* if <tt>toKey</tt> does not implement <tt>Comparable</tt>).
278			* @throws NullPointerException if <tt>toKey</tt> is <tt>null</tt>
279			* and this map does not support <tt>null</tt> keys.
280			*/
281	dl	1.3	NavigableMap<K,V> navigableHeadMap(K toKey);
282	dl	1.1
283			/**
284			* Returns a view of the portion of this map whose keys are
285	dl	1.3	* greater than or equal to <tt>fromKey</tt>. The returned navigable
286			* map is backed by this map, so changes in the returned navigable
287	dl	1.1	* map are reflected in this map, and vice-versa.
288			* @param fromKey low endpoint (inclusive) of the tailMap.
289			* @return a view of the portion of this map whose keys are greater
290			* than or equal to <tt>fromKey</tt>.
291			* @throws ClassCastException if <tt>fromKey</tt> is not compatible
292			* with this map's comparator (or, if the map has no comparator,
293			* if <tt>fromKey</tt> does not implement <tt>Comparable</tt>).
294			* @throws NullPointerException if <tt>fromKey</tt> is <tt>null</tt>
295			* and this map does not support <tt>null</tt> keys.
296			*/
297	dl	1.3	NavigableMap<K,V> navigableTailMap(K fromKey);
298	dl	1.1	}