java/util/NavigableMap.java

/*
 * Written by Doug Lea and Josh Bloch 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
 * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
 * and {@code higherEntry} return {@code Map.Entry} objects
 * associated with keys respectively less than, less than or equal,
 * greater than or equal, and greater than a given key, returning
 * {@code null} if there is no such key.  Similarly, methods
 * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
 * {@code higherKey} return only the associated keys. All of these
 * methods are designed for locating, not traversing entries.
 *
 * <p>A {@code NavigableMap} may be accessed and traversed in either
 * ascending or descending key order.  The {@code descendingMap}
 * method returns a view of the map with the senses of all relational
 * and directional methods inverted. The performance of ascending
 * operations and views is likely to be faster than that of descending
 * ones.  Methods {@code subMap}, {@code headMap},
 * and {@code tailMap} differ from the like-named {@code
 * SortedMap} methods in accepting additional arguments describing
 * whether lower and upper bounds are inclusive versus exclusive.
 * Submaps of any {@code NavigableMap} must implement the {@code
 * NavigableMap} interface.
 *
 * <p>This interface additionally defines methods {@code firstEntry},
 * {@code pollFirstEntry}, {@code lastEntry}, and
 * {@code pollLastEntry} that return and/or remove the least and
 * greatest mappings, if any exist, else returning {@code null}.
 *
 * <p> Implementations of entry-returning methods are expected to
 * return {@code Map.Entry} pairs representing snapshots of mappings
 * at the time they were produced, and thus generally do <em>not</em>
 * support the optional {@code Entry.setValue} method. Note however
 * that it is possible to change mappings in the associated map using
 * method {@code put}.
 *
 * <p>This interface is a member of the
 * <a href="{@docRoot}/../guide/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @author Doug Lea
 * @author Josh Bloch
 * @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 greatest key
     * strictly less than the given key, or {@code null} if there is
     * no such key.
     *
     * @param key the key
     * @return an entry with the greatest key less than {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    Map.Entry<K,V> lowerEntry(K key);

    /**
     * Returns the greatest key strictly less than the given key, or
     * {@code null} if there is no such key.
     *
     * @param key the key
     * @return the greatest key less than {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    K lowerKey(K key);

    /**
     * Returns a key-value mapping associated with the greatest key
     * less than or equal to the given key, or {@code null} if there
     * is no such key.
     *
     * @param key the key
     * @return an entry with the greatest key less than or equal to
     *         {@code key}, or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    Map.Entry<K,V> floorEntry(K key);

    /**
     * Returns the greatest key less than or equal to the given key,
     * or {@code null} if there is no such key.
     *
     * @param key the key
     * @return the greatest key less than or equal to {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    K floorKey(K key);

    /**
     * Returns a key-value mapping associated with the least key
     * greater than or equal to the given key, or {@code null} if
     * there is no such key.
     *
     * @param key the key
     * @return an entry with the least key greater than or equal to
     *         {@code key}, or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    Map.Entry<K,V> ceilingEntry(K key);

    /**
     * Returns the least key greater than or equal to the given key,
     * or {@code null} if there is no such key.
     *
     * @param key the key
     * @return the least key greater than or equal to {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    K ceilingKey(K key);

    /**
     * Returns a key-value mapping associated with the least key
     * strictly greater than the given key, or {@code null} if there
     * is no such key.
     *
     * @param key the key
     * @return an entry with the least key greater than {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    Map.Entry<K,V> higherEntry(K key);

    /**
     * Returns the least key strictly greater than the given key, or
     * {@code null} if there is no such key.
     *
     * @param key the key
     * @return the least key greater than {@code key},
     *         or {@code null} if there is no such key
     * @throws ClassCastException if the specified key cannot be compared
     *         with the keys currently in the map
     * @throws NullPointerException if the specified key is null
     *         and this map does not permit null keys
     */
    K higherKey(K key);

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

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

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

    /**
     * Removes and returns a key-value mapping associated with
     * the greatest key in this map, or {@code null} if the map is empty.
     *
     * @return the removed last entry of this map,
     *         or {@code null} if this map is empty
     */
    Map.Entry<K,V> pollLastEntry();

    /**
     * Returns a {@link NavigableMap} view of the mappings contained in this
     * map in descending order.  The descending map is backed by this map, so
     * changes to the map are reflected in the descending set, and vice-versa.
     * If either map is modified while an iteration over a collection view of
     * the other map is in progress (except through the iterator's own
     * {@code remove} operation), the results of the iteration are undefined.
     *
     * @return a navigable map view of the mappings contained in this map,
     *     sorted in descending order
     */
    NavigableMap<K,V> descendingMap();

    /**
     * Returns a navigable set view of the keys contained in this navigable
     * map.  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
     * {@code remove} operation), the results of the iteration are undefined.
     * The set supports element removal, which removes the corresponding
     * mapping from the map, via the {@code Iterator.remove},
     * {@code Set.remove}, {@code removeAll} {@code retainAll}, and
     * {@code clear} operations.  It does not support the {@code add} or
     * {@code addAll} operations.
     *
     * @return a navigable set view of the keys contained in this navigable map
     */
    NavigableSet<K> navigableKeySet();

    /**
     * Returns a {@link NavigableSet} view of the keys contained in this map.
     * The set's iterator returns the keys in descending order.
     * The set is backed by the map, so changes to the map are
     * reflected in the set, and vice-versa.  If the map is modified
     * while an iteration over the set is in progress (except through
     * the iterator's own <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 <tt>add</tt> or <tt>addAll</tt>
     * operations.
     *
     * @return a set view of the keys contained in this map, sorted in
     *         descending order
     */
    NavigableSet<K> descendingKeySet();

    /**
     * Returns a view of the portion of this map whose keys range from
     * {@code fromKey} to {@code toKey}.  If {@code fromKey} and
     * {@code toKey} are equal, the returned map is empty unless
     * {@code fromExclusive} and {@code toExclusive} are both true.  The
     * returned map is backed by this map, so changes in the returned map are
     * reflected in this map, and vice-versa.  The returned map supports all
     * optional map operations that this map supports.
     *
     * <p>The returned map will throw an {@code IllegalArgumentException}
     * on an attempt to insert a key outside of its range, or to construct a
     * submap either of whose endpoints lie outside its range.
     *
     * @param fromKey low endpoint of the keys in the returned map
     * @param fromInclusive true if the low endpoint ({@code fromKey}) is
     *        to be included in the returned view
     * @param toKey high endpoint of the keys in the returned map
     * @param toInclusive true if the high endpoint ({@code toKey}) is
     *        to be included in the returned view
     * @return a view of the portion of this map whose keys range from
     *         {@code fromKey} to {@code toKey}
     * @throws ClassCastException if {@code fromKey} and {@code toKey}
     *         cannot be compared to one another using this map's comparator
     *         (or, if the map has no comparator, using natural ordering).
     *         Implementations may, but are not required to, throw this
     *         exception if {@code fromKey} or {@code toKey}
     *         cannot be compared to keys currently in the map.
     * @throws NullPointerException if {@code fromKey} or {@code toKey}
     *         is null and this map does not permit null keys
     * @throws IllegalArgumentException if {@code fromKey} is greater than
     *         {@code toKey}; or if this map itself has a restricted
     *         range, and {@code fromKey} or {@code toKey} lies
     *         outside the bounds of the range
     */
    NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,
                             K toKey,   boolean toInclusive);

    /**
     * Returns a view of the portion of this map whose keys are less than (or
     * equal to, if {@code inclusive} is true) {@code toKey}.  The returned
     * map is backed by this map, so changes in the returned map are reflected
     * in this map, and vice-versa.  The returned map supports all optional
     * map operations that this map supports.
     *
     * <p>The returned map will throw an {@code IllegalArgumentException}
     * on an attempt to insert a key outside its range.
     *
     * @param toKey high endpoint of the keys in the returned map
     * @param inclusive true if the high endpoint ({@code toKey}) is
     *        to be included in the returned view
     * @return a view of the portion of this map whose keys are less than
     *         (or equal to, if {@code inclusive} is true) {@code toKey}
     * @throws ClassCastException if {@code toKey} is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if {@code toKey} does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if {@code toKey} cannot be compared to keys
     *         currently in the map.
     * @throws NullPointerException if {@code toKey} is null
     *         and this map does not permit null keys
     * @throws IllegalArgumentException if this map itself has a
     *         restricted range, and {@code toKey} lies outside the
     *         bounds of the range
     */
    NavigableMap<K,V> headMap(K toKey, boolean inclusive);

    /**
     * Returns a view of the portion of this map whose keys are greater than (or
     * equal to, if {@code inclusive} is true) {@code fromKey}.  The returned
     * map is backed by this map, so changes in the returned map are reflected
     * in this map, and vice-versa.  The returned map supports all optional
     * map operations that this map supports.
     *
     * <p>The returned map will throw an {@code IllegalArgumentException}
     * on an attempt to insert a key outside its range.
     *
     * @param fromKey low endpoint of the keys in the returned map
     * @param inclusive true if the low endpoint ({@code fromKey}) is
     *        to be included in the returned view
     * @return a view of the portion of this map whose keys are greater than
     *         (or equal to, if {@code inclusive} is true) {@code fromKey}
     * @throws ClassCastException if {@code fromKey} is not compatible
     *         with this map's comparator (or, if the map has no comparator,
     *         if {@code fromKey} does not implement {@link Comparable}).
     *         Implementations may, but are not required to, throw this
     *         exception if {@code fromKey} cannot be compared to keys
     *         currently in the map.
     * @throws NullPointerException if {@code fromKey} is null
     *         and this map does not permit null keys
     * @throws IllegalArgumentException if this map itself has a
     *         restricted range, and {@code fromKey} lies outside the
     *         bounds of the range
     */
    NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);
}
Revision:	1.16
Committed:	Thu Apr 20 21:55:42 2006 UTC (18 years ago) by jsr166
Branch:	MAIN
Changes since 1.15:	+4 -4 lines
Log Message:	the the
#	Content
1	/*
2	* Written by Doug Lea and Josh Bloch with assistance from members of JCP
3	* JSR-166 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	* {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
13	* and {@code higherEntry} return {@code Map.Entry} 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	* {@code null} if there is no such key. Similarly, methods
17	* {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
18	* {@code higherKey} return only the associated keys. All of these
19	* methods are designed for locating, not traversing entries.
20	*
21	* <p>A {@code NavigableMap} may be accessed and traversed in either
22	* ascending or descending key order. The {@code descendingMap}
23	* method returns a view of the map with the senses of all relational
24	* and directional methods inverted. The performance of ascending
25	* operations and views is likely to be faster than that of descending
26	* ones. Methods {@code subMap}, {@code headMap},
27	* and {@code tailMap} differ from the like-named {@code
28	* SortedMap} methods in accepting additional arguments describing
29	* whether lower and upper bounds are inclusive versus exclusive.
30	* Submaps of any {@code NavigableMap} must implement the {@code
31	* NavigableMap} interface.
32	*
33	* <p>This interface additionally defines methods {@code firstEntry},
34	* {@code pollFirstEntry}, {@code lastEntry}, and
35	* {@code pollLastEntry} that return and/or remove the least and
36	* greatest mappings, if any exist, else returning {@code null}.
37	*
38	* <p> Implementations of entry-returning methods are expected to
39	* return {@code Map.Entry} pairs representing snapshots of mappings
40	* at the time they were produced, and thus generally do <em>not</em>
41	* support the optional {@code Entry.setValue} method. Note however
42	* that it is possible to change mappings in the associated map using
43	* method {@code put}.
44	*
45	* <p>This interface is a member of the
46	* <a href="{@docRoot}/../guide/collections/index.html">
47	* Java Collections Framework</a>.
48	*
49	* @author Doug Lea
50	* @author Josh Bloch
51	* @param <K> the type of keys maintained by this map
52	* @param <V> the type of mapped values
53	* @since 1.6
54	*/
55	public interface NavigableMap<K,V> extends SortedMap<K,V> {
56	/**
57	* Returns a key-value mapping associated with the greatest key
58	* strictly less than the given key, or {@code null} if there is
59	* no such key.
60	*
61	* @param key the key
62	* @return an entry with the greatest key less than {@code key},
63	* or {@code null} if there is no such key
64	* @throws ClassCastException if the specified key cannot be compared
65	* with the keys currently in the map
66	* @throws NullPointerException if the specified key is null
67	* and this map does not permit null keys
68	*/
69	Map.Entry<K,V> lowerEntry(K key);
70
71	/**
72	* Returns the greatest key strictly less than the given key, or
73	* {@code null} if there is no such key.
74	*
75	* @param key the key
76	* @return the greatest key less than {@code key},
77	* or {@code null} if there is no such key
78	* @throws ClassCastException if the specified key cannot be compared
79	* with the keys currently in the map
80	* @throws NullPointerException if the specified key is null
81	* and this map does not permit null keys
82	*/
83	K lowerKey(K key);
84
85	/**
86	* Returns a key-value mapping associated with the greatest key
87	* less than or equal to the given key, or {@code null} if there
88	* is no such key.
89	*
90	* @param key the key
91	* @return an entry with the greatest key less than or equal to
92	* {@code key}, or {@code null} if there is no such key
93	* @throws ClassCastException if the specified key cannot be compared
94	* with the keys currently in the map
95	* @throws NullPointerException if the specified key is null
96	* and this map does not permit null keys
97	*/
98	Map.Entry<K,V> floorEntry(K key);
99
100	/**
101	* Returns the greatest key less than or equal to the given key,
102	* or {@code null} if there is no such key.
103	*
104	* @param key the key
105	* @return the greatest key less than or equal to {@code key},
106	* or {@code null} if there is no such key
107	* @throws ClassCastException if the specified key cannot be compared
108	* with the keys currently in the map
109	* @throws NullPointerException if the specified key is null
110	* and this map does not permit null keys
111	*/
112	K floorKey(K key);
113
114	/**
115	* Returns a key-value mapping associated with the least key
116	* greater than or equal to the given key, or {@code null} if
117	* there is no such key.
118	*
119	* @param key the key
120	* @return an entry with the least key greater than or equal to
121	* {@code key}, or {@code null} if there is no such key
122	* @throws ClassCastException if the specified key cannot be compared
123	* with the keys currently in the map
124	* @throws NullPointerException if the specified key is null
125	* and this map does not permit null keys
126	*/
127	Map.Entry<K,V> ceilingEntry(K key);
128
129	/**
130	* Returns the least key greater than or equal to the given key,
131	* or {@code null} if there is no such key.
132	*
133	* @param key the key
134	* @return the least key greater than or equal to {@code key},
135	* or {@code null} if there is no such key
136	* @throws ClassCastException if the specified key cannot be compared
137	* with the keys currently in the map
138	* @throws NullPointerException if the specified key is null
139	* and this map does not permit null keys
140	*/
141	K ceilingKey(K key);
142
143	/**
144	* Returns a key-value mapping associated with the least key
145	* strictly greater than the given key, or {@code null} if there
146	* is no such key.
147	*
148	* @param key the key
149	* @return an entry with the least key greater than {@code key},
150	* or {@code null} if there is no such key
151	* @throws ClassCastException if the specified key cannot be compared
152	* with the keys currently in the map
153	* @throws NullPointerException if the specified key is null
154	* and this map does not permit null keys
155	*/
156	Map.Entry<K,V> higherEntry(K key);
157
158	/**
159	* Returns the least key strictly greater than the given key, or
160	* {@code null} if there is no such key.
161	*
162	* @param key the key
163	* @return the least key greater than {@code key},
164	* or {@code null} if there is no such key
165	* @throws ClassCastException if the specified key cannot be compared
166	* with the keys currently in the map
167	* @throws NullPointerException if the specified key is null
168	* and this map does not permit null keys
169	*/
170	K higherKey(K key);
171
172	/**
173	* Returns a key-value mapping associated with the least
174	* key in this map, or {@code null} if the map is empty.
175	*
176	* @return an entry with the least key,
177	* or {@code null} if this map is empty
178	*/
179	Map.Entry<K,V> firstEntry();
180
181	/**
182	* Returns a key-value mapping associated with the greatest
183	* key in this map, or {@code null} if the map is empty.
184	*
185	* @return an entry with the greatest key,
186	* or {@code null} if this map is empty
187	*/
188	Map.Entry<K,V> lastEntry();
189
190	/**
191	* Removes and returns a key-value mapping associated with
192	* the least key in this map, or {@code null} if the map is empty.
193	*
194	* @return the removed first entry of this map,
195	* or {@code null} if this map is empty
196	*/
197	Map.Entry<K,V> pollFirstEntry();
198
199	/**
200	* Removes and returns a key-value mapping associated with
201	* the greatest key in this map, or {@code null} if the map is empty.
202	*
203	* @return the removed last entry of this map,
204	* or {@code null} if this map is empty
205	*/
206	Map.Entry<K,V> pollLastEntry();
207
208	/**
209	* Returns a {@link NavigableMap} view of the mappings contained in this
210	* map in descending order. The descending map is backed by this map, so
211	* changes to the map are reflected in the descending set, and vice-versa.
212	* If either map is modified while an iteration over a collection view of
213	* the other map is in progress (except through the iterator's own
214	* {@code remove} operation), the results of the iteration are undefined.
215	*
216	* @return a navigable map view of the mappings contained in this map,
217	* sorted in descending order
218	*/
219	NavigableMap<K,V> descendingMap();
220
221	/**
222	* Returns a navigable set view of the keys contained in this navigable
223	* map. The set is backed by the map, so changes to the map are reflected
224	* in the set, and vice-versa. If the map is modified while an iteration
225	* over the set is in progress (except through the iterator's own
226	* {@code remove} operation), the results of the iteration are undefined.
227	* The set supports element removal, which removes the corresponding
228	* mapping from the map, via the {@code Iterator.remove},
229	* {@code Set.remove}, {@code removeAll} {@code retainAll}, and
230	* {@code clear} operations. It does not support the {@code add} or
231	* {@code addAll} operations.
232	*
233	* @return a navigable set view of the keys contained in this navigable map
234	*/
235	NavigableSet<K> navigableKeySet();
236
237	/**
238	* Returns a {@link NavigableSet} view of the keys contained in this map.
239	* The set's iterator returns the keys in descending order.
240	* The set is backed by the map, so changes to the map are
241	* reflected in the set, and vice-versa. If the map is modified
242	* while an iteration over the set is in progress (except through
243	* the iterator's own <tt>remove</tt> operation), the results of
244	* the iteration are undefined. The set supports element removal,
245	* which removes the corresponding mapping from the map, via the
246	* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
247	* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
248	* operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
249	* operations.
250	*
251	* @return a set view of the keys contained in this map, sorted in
252	* descending order
253	*/
254	NavigableSet<K> descendingKeySet();
255
256	/**
257	* Returns a view of the portion of this map whose keys range from
258	* {@code fromKey} to {@code toKey}. If {@code fromKey} and
259	* {@code toKey} are equal, the returned map is empty unless
260	* {@code fromExclusive} and {@code toExclusive} are both true. The
261	* returned map is backed by this map, so changes in the returned map are
262	* reflected in this map, and vice-versa. The returned map supports all
263	* optional map operations that this map supports.
264	*
265	* <p>The returned map will throw an {@code IllegalArgumentException}
266	* on an attempt to insert a key outside of its range, or to construct a
267	* submap either of whose endpoints lie outside its range.
268	*
269	* @param fromKey low endpoint of the keys in the returned map
270	* @param fromInclusive true if the low endpoint ({@code fromKey}) is
271	* to be included in the returned view
272	* @param toKey high endpoint of the keys in the returned map
273	* @param toInclusive true if the high endpoint ({@code toKey}) is
274	* to be included in the returned view
275	* @return a view of the portion of this map whose keys range from
276	* {@code fromKey} to {@code toKey}
277	* @throws ClassCastException if {@code fromKey} and {@code toKey}
278	* cannot be compared to one another using this map's comparator
279	* (or, if the map has no comparator, using natural ordering).
280	* Implementations may, but are not required to, throw this
281	* exception if {@code fromKey} or {@code toKey}
282	* cannot be compared to keys currently in the map.
283	* @throws NullPointerException if {@code fromKey} or {@code toKey}
284	* is null and this map does not permit null keys
285	* @throws IllegalArgumentException if {@code fromKey} is greater than
286	* {@code toKey}; or if this map itself has a restricted
287	* range, and {@code fromKey} or {@code toKey} lies
288	* outside the bounds of the range
289	*/
290	NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive,
291	K toKey, boolean toInclusive);
292
293	/**
294	* Returns a view of the portion of this map whose keys are less than (or
295	* equal to, if {@code inclusive} is true) {@code toKey}. The returned
296	* map is backed by this map, so changes in the returned map are reflected
297	* in this map, and vice-versa. The returned map supports all optional
298	* map operations that this map supports.
299	*
300	* <p>The returned map will throw an {@code IllegalArgumentException}
301	* on an attempt to insert a key outside its range.
302	*
303	* @param toKey high endpoint of the keys in the returned map
304	* @param inclusive true if the high endpoint ({@code toKey}) is
305	* to be included in the returned view
306	* @return a view of the portion of this map whose keys are less than
307	* (or equal to, if {@code inclusive} is true) {@code toKey}
308	* @throws ClassCastException if {@code toKey} is not compatible
309	* with this map's comparator (or, if the map has no comparator,
310	* if {@code toKey} does not implement {@link Comparable}).
311	* Implementations may, but are not required to, throw this
312	* exception if {@code toKey} cannot be compared to keys
313	* currently in the map.
314	* @throws NullPointerException if {@code toKey} is null
315	* and this map does not permit null keys
316	* @throws IllegalArgumentException if this map itself has a
317	* restricted range, and {@code toKey} lies outside the
318	* bounds of the range
319	*/
320	NavigableMap<K,V> headMap(K toKey, boolean inclusive);
321
322	/**
323	* Returns a view of the portion of this map whose keys are greater than (or
324	* equal to, if {@code inclusive} is true) {@code fromKey}. The returned
325	* map is backed by this map, so changes in the returned map are reflected
326	* in this map, and vice-versa. The returned map supports all optional
327	* map operations that this map supports.
328	*
329	* <p>The returned map will throw an {@code IllegalArgumentException}
330	* on an attempt to insert a key outside its range.
331	*
332	* @param fromKey low endpoint of the keys in the returned map
333	* @param inclusive true if the low endpoint ({@code fromKey}) is
334	* to be included in the returned view
335	* @return a view of the portion of this map whose keys are greater than
336	* (or equal to, if {@code inclusive} is true) {@code fromKey}
337	* @throws ClassCastException if {@code fromKey} is not compatible
338	* with this map's comparator (or, if the map has no comparator,
339	* if {@code fromKey} does not implement {@link Comparable}).
340	* Implementations may, but are not required to, throw this
341	* exception if {@code fromKey} cannot be compared to keys
342	* currently in the map.
343	* @throws NullPointerException if {@code fromKey} is null
344	* and this map does not permit null keys
345	* @throws IllegalArgumentException if this map itself has a
346	* restricted range, and {@code fromKey} lies outside the
347	* bounds of the range
348	*/
349	NavigableMap<K,V> tailMap(K fromKey, boolean inclusive);
350	}