001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
003: *
004: * This code is free software; you can redistribute it and/or modify it
005: * under the terms of the GNU General Public License version 2 only, as
006: * published by the Free Software Foundation. Sun designates this
007: * particular file as subject to the "Classpath" exception as provided
008: * by Sun in the LICENSE file that accompanied this code.
009: *
010: * This code is distributed in the hope that it will be useful, but WITHOUT
011: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
012: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
013: * version 2 for more details (a copy is included in the LICENSE file that
014: * accompanied this code).
015: *
016: * You should have received a copy of the GNU General Public License version
017: * 2 along with this work; if not, write to the Free Software Foundation,
018: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
019: *
020: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
021: * CA 95054 USA or visit www.sun.com if you need additional information or
022: * have any questions.
023: */
024:
025: /*
026: * This file is available under and governed by the GNU General Public
027: * License version 2 only, as published by the Free Software Foundation.
028: * However, the following notice accompanied the original version of this
029: * file:
030: *
031: * Written by Doug Lea and Josh Bloch with assistance from members of JCP
032: * JSR-166 Expert Group and released to the public domain, as explained at
033: * http://creativecommons.org/licenses/publicdomain
034: */
035:
036: package java.util;
037:
038: /**
039: * A {@link SortedMap} extended with navigation methods returning the
040: * closest matches for given search targets. Methods
041: * {@code lowerEntry}, {@code floorEntry}, {@code ceilingEntry},
042: * and {@code higherEntry} return {@code Map.Entry} objects
043: * associated with keys respectively less than, less than or equal,
044: * greater than or equal, and greater than a given key, returning
045: * {@code null} if there is no such key. Similarly, methods
046: * {@code lowerKey}, {@code floorKey}, {@code ceilingKey}, and
047: * {@code higherKey} return only the associated keys. All of these
048: * methods are designed for locating, not traversing entries.
049: *
050: * <p>A {@code NavigableMap} may be accessed and traversed in either
051: * ascending or descending key order. The {@code descendingMap}
052: * method returns a view of the map with the senses of all relational
053: * and directional methods inverted. The performance of ascending
054: * operations and views is likely to be faster than that of descending
055: * ones. Methods {@code subMap}, {@code headMap},
056: * and {@code tailMap} differ from the like-named {@code
057: * SortedMap} methods in accepting additional arguments describing
058: * whether lower and upper bounds are inclusive versus exclusive.
059: * Submaps of any {@code NavigableMap} must implement the {@code
060: * NavigableMap} interface.
061: *
062: * <p>This interface additionally defines methods {@code firstEntry},
063: * {@code pollFirstEntry}, {@code lastEntry}, and
064: * {@code pollLastEntry} that return and/or remove the least and
065: * greatest mappings, if any exist, else returning {@code null}.
066: *
067: * <p>Implementations of entry-returning methods are expected to
068: * return {@code Map.Entry} pairs representing snapshots of mappings
069: * at the time they were produced, and thus generally do <em>not</em>
070: * support the optional {@code Entry.setValue} method. Note however
071: * that it is possible to change mappings in the associated map using
072: * method {@code put}.
073: *
074: * <p>Methods
075: * {@link #subMap(Object, Object) subMap(K, K)},
076: * {@link #headMap(Object) headMap(K)}, and
077: * {@link #tailMap(Object) tailMap(K)}
078: * are specified to return {@code SortedMap} to allow existing
079: * implementations of {@code SortedMap} to be compatibly retrofitted to
080: * implement {@code NavigableMap}, but extensions and implementations
081: * of this interface are encouraged to override these methods to return
082: * {@code NavigableMap}. Similarly,
083: * {@link #keySet()} can be overriden to return {@code NavigableSet}.
084: *
085: * <p>This interface is a member of the
086: * <a href="{@docRoot}/../technotes/guides/collections/index.html">
087: * Java Collections Framework</a>.
088: *
089: * @author Doug Lea
090: * @author Josh Bloch
091: * @param <K> the type of keys maintained by this map
092: * @param <V> the type of mapped values
093: * @since 1.6
094: */
095: public interface NavigableMap<K, V> extends SortedMap<K, V> {
096: /**
097: * Returns a key-value mapping associated with the greatest key
098: * strictly less than the given key, or {@code null} if there is
099: * no such key.
100: *
101: * @param key the key
102: * @return an entry with the greatest key less than {@code key},
103: * or {@code null} if there is no such key
104: * @throws ClassCastException if the specified key cannot be compared
105: * with the keys currently in the map
106: * @throws NullPointerException if the specified key is null
107: * and this map does not permit null keys
108: */
109: Map.Entry<K, V> lowerEntry(K key);
110:
111: /**
112: * Returns the greatest key strictly less than the given key, or
113: * {@code null} if there is no such key.
114: *
115: * @param key the key
116: * @return the greatest key less than {@code key},
117: * or {@code null} if there is no such key
118: * @throws ClassCastException if the specified key cannot be compared
119: * with the keys currently in the map
120: * @throws NullPointerException if the specified key is null
121: * and this map does not permit null keys
122: */
123: K lowerKey(K key);
124:
125: /**
126: * Returns a key-value mapping associated with the greatest key
127: * less than or equal to the given key, or {@code null} if there
128: * is no such key.
129: *
130: * @param key the key
131: * @return an entry with the greatest key less than or equal to
132: * {@code key}, or {@code null} if there is no such key
133: * @throws ClassCastException if the specified key cannot be compared
134: * with the keys currently in the map
135: * @throws NullPointerException if the specified key is null
136: * and this map does not permit null keys
137: */
138: Map.Entry<K, V> floorEntry(K key);
139:
140: /**
141: * Returns the greatest key less than or equal to the given key,
142: * or {@code null} if there is no such key.
143: *
144: * @param key the key
145: * @return the greatest key less than or equal to {@code key},
146: * or {@code null} if there is no such key
147: * @throws ClassCastException if the specified key cannot be compared
148: * with the keys currently in the map
149: * @throws NullPointerException if the specified key is null
150: * and this map does not permit null keys
151: */
152: K floorKey(K key);
153:
154: /**
155: * Returns a key-value mapping associated with the least key
156: * greater than or equal to the given key, or {@code null} if
157: * there is no such key.
158: *
159: * @param key the key
160: * @return an entry with the least key greater than or equal to
161: * {@code key}, or {@code null} if there is no such key
162: * @throws ClassCastException if the specified key cannot be compared
163: * with the keys currently in the map
164: * @throws NullPointerException if the specified key is null
165: * and this map does not permit null keys
166: */
167: Map.Entry<K, V> ceilingEntry(K key);
168:
169: /**
170: * Returns the least key greater than or equal to the given key,
171: * or {@code null} if there is no such key.
172: *
173: * @param key the key
174: * @return the least key greater than or equal to {@code key},
175: * or {@code null} if there is no such key
176: * @throws ClassCastException if the specified key cannot be compared
177: * with the keys currently in the map
178: * @throws NullPointerException if the specified key is null
179: * and this map does not permit null keys
180: */
181: K ceilingKey(K key);
182:
183: /**
184: * Returns a key-value mapping associated with the least key
185: * strictly greater than the given key, or {@code null} if there
186: * is no such key.
187: *
188: * @param key the key
189: * @return an entry with the least key greater than {@code key},
190: * or {@code null} if there is no such key
191: * @throws ClassCastException if the specified key cannot be compared
192: * with the keys currently in the map
193: * @throws NullPointerException if the specified key is null
194: * and this map does not permit null keys
195: */
196: Map.Entry<K, V> higherEntry(K key);
197:
198: /**
199: * Returns the least key strictly greater than the given key, or
200: * {@code null} if there is no such key.
201: *
202: * @param key the key
203: * @return the least key greater than {@code key},
204: * or {@code null} if there is no such key
205: * @throws ClassCastException if the specified key cannot be compared
206: * with the keys currently in the map
207: * @throws NullPointerException if the specified key is null
208: * and this map does not permit null keys
209: */
210: K higherKey(K key);
211:
212: /**
213: * Returns a key-value mapping associated with the least
214: * key in this map, or {@code null} if the map is empty.
215: *
216: * @return an entry with the least key,
217: * or {@code null} if this map is empty
218: */
219: Map.Entry<K, V> firstEntry();
220:
221: /**
222: * Returns a key-value mapping associated with the greatest
223: * key in this map, or {@code null} if the map is empty.
224: *
225: * @return an entry with the greatest key,
226: * or {@code null} if this map is empty
227: */
228: Map.Entry<K, V> lastEntry();
229:
230: /**
231: * Removes and returns a key-value mapping associated with
232: * the least key in this map, or {@code null} if the map is empty.
233: *
234: * @return the removed first entry of this map,
235: * or {@code null} if this map is empty
236: */
237: Map.Entry<K, V> pollFirstEntry();
238:
239: /**
240: * Removes and returns a key-value mapping associated with
241: * the greatest key in this map, or {@code null} if the map is empty.
242: *
243: * @return the removed last entry of this map,
244: * or {@code null} if this map is empty
245: */
246: Map.Entry<K, V> pollLastEntry();
247:
248: /**
249: * Returns a reverse order view of the mappings contained in this map.
250: * The descending map is backed by this map, so changes to the map are
251: * reflected in the descending map, and vice-versa. If either map is
252: * modified while an iteration over a collection view of either map
253: * is in progress (except through the iterator's own {@code remove}
254: * operation), the results of the iteration are undefined.
255: *
256: * <p>The returned map has an ordering equivalent to
257: * <tt>{@link Collections#reverseOrder(Comparator) Collections.reverseOrder}(comparator())</tt>.
258: * The expression {@code m.descendingMap().descendingMap()} returns a
259: * view of {@code m} essentially equivalent to {@code m}.
260: *
261: * @return a reverse order view of this map
262: */
263: NavigableMap<K, V> descendingMap();
264:
265: /**
266: * Returns a {@link NavigableSet} view of the keys contained in this map.
267: * The set's iterator returns the keys in ascending order.
268: * The set is backed by the map, so changes to the map are reflected in
269: * the set, and vice-versa. If the map is modified while an iteration
270: * over the set is in progress (except through the iterator's own {@code
271: * remove} operation), the results of the iteration are undefined. The
272: * set supports element removal, which removes the corresponding mapping
273: * from the map, via the {@code Iterator.remove}, {@code Set.remove},
274: * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
275: * It does not support the {@code add} or {@code addAll} operations.
276: *
277: * @return a navigable set view of the keys in this map
278: */
279: NavigableSet<K> navigableKeySet();
280:
281: /**
282: * Returns a reverse order {@link NavigableSet} view of the keys contained in this map.
283: * The set's iterator returns the keys in descending order.
284: * The set is backed by the map, so changes to the map are reflected in
285: * the set, and vice-versa. If the map is modified while an iteration
286: * over the set is in progress (except through the iterator's own {@code
287: * remove} operation), the results of the iteration are undefined. The
288: * set supports element removal, which removes the corresponding mapping
289: * from the map, via the {@code Iterator.remove}, {@code Set.remove},
290: * {@code removeAll}, {@code retainAll}, and {@code clear} operations.
291: * It does not support the {@code add} or {@code addAll} operations.
292: *
293: * @return a reverse order navigable set view of the keys in this map
294: */
295: NavigableSet<K> descendingKeySet();
296:
297: /**
298: * Returns a view of the portion of this map whose keys range from
299: * {@code fromKey} to {@code toKey}. If {@code fromKey} and
300: * {@code toKey} are equal, the returned map is empty unless
301: * {@code fromExclusive} and {@code toExclusive} are both true. The
302: * returned map is backed by this map, so changes in the returned map are
303: * reflected in this map, and vice-versa. The returned map supports all
304: * optional map operations that this map supports.
305: *
306: * <p>The returned map will throw an {@code IllegalArgumentException}
307: * on an attempt to insert a key outside of its range, or to construct a
308: * submap either of whose endpoints lie outside its range.
309: *
310: * @param fromKey low endpoint of the keys in the returned map
311: * @param fromInclusive {@code true} if the low endpoint
312: * is to be included in the returned view
313: * @param toKey high endpoint of the keys in the returned map
314: * @param toInclusive {@code true} if the high endpoint
315: * is to be included in the returned view
316: * @return a view of the portion of this map whose keys range from
317: * {@code fromKey} to {@code toKey}
318: * @throws ClassCastException if {@code fromKey} and {@code toKey}
319: * cannot be compared to one another using this map's comparator
320: * (or, if the map has no comparator, using natural ordering).
321: * Implementations may, but are not required to, throw this
322: * exception if {@code fromKey} or {@code toKey}
323: * cannot be compared to keys currently in the map.
324: * @throws NullPointerException if {@code fromKey} or {@code toKey}
325: * is null and this map does not permit null keys
326: * @throws IllegalArgumentException if {@code fromKey} is greater than
327: * {@code toKey}; or if this map itself has a restricted
328: * range, and {@code fromKey} or {@code toKey} lies
329: * outside the bounds of the range
330: */
331: NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive,
332: K toKey, boolean toInclusive);
333:
334: /**
335: * Returns a view of the portion of this map whose keys are less than (or
336: * equal to, if {@code inclusive} is true) {@code toKey}. The returned
337: * map is backed by this map, so changes in the returned map are reflected
338: * in this map, and vice-versa. The returned map supports all optional
339: * map operations that this map supports.
340: *
341: * <p>The returned map will throw an {@code IllegalArgumentException}
342: * on an attempt to insert a key outside its range.
343: *
344: * @param toKey high endpoint of the keys in the returned map
345: * @param inclusive {@code true} if the high endpoint
346: * is to be included in the returned view
347: * @return a view of the portion of this map whose keys are less than
348: * (or equal to, if {@code inclusive} is true) {@code toKey}
349: * @throws ClassCastException if {@code toKey} is not compatible
350: * with this map's comparator (or, if the map has no comparator,
351: * if {@code toKey} does not implement {@link Comparable}).
352: * Implementations may, but are not required to, throw this
353: * exception if {@code toKey} cannot be compared to keys
354: * currently in the map.
355: * @throws NullPointerException if {@code toKey} is null
356: * and this map does not permit null keys
357: * @throws IllegalArgumentException if this map itself has a
358: * restricted range, and {@code toKey} lies outside the
359: * bounds of the range
360: */
361: NavigableMap<K, V> headMap(K toKey, boolean inclusive);
362:
363: /**
364: * Returns a view of the portion of this map whose keys are greater than (or
365: * equal to, if {@code inclusive} is true) {@code fromKey}. The returned
366: * map is backed by this map, so changes in the returned map are reflected
367: * in this map, and vice-versa. The returned map supports all optional
368: * map operations that this map supports.
369: *
370: * <p>The returned map will throw an {@code IllegalArgumentException}
371: * on an attempt to insert a key outside its range.
372: *
373: * @param fromKey low endpoint of the keys in the returned map
374: * @param inclusive {@code true} if the low endpoint
375: * is to be included in the returned view
376: * @return a view of the portion of this map whose keys are greater than
377: * (or equal to, if {@code inclusive} is true) {@code fromKey}
378: * @throws ClassCastException if {@code fromKey} is not compatible
379: * with this map's comparator (or, if the map has no comparator,
380: * if {@code fromKey} does not implement {@link Comparable}).
381: * Implementations may, but are not required to, throw this
382: * exception if {@code fromKey} cannot be compared to keys
383: * currently in the map.
384: * @throws NullPointerException if {@code fromKey} is null
385: * and this map does not permit null keys
386: * @throws IllegalArgumentException if this map itself has a
387: * restricted range, and {@code fromKey} lies outside the
388: * bounds of the range
389: */
390: NavigableMap<K, V> tailMap(K fromKey, boolean inclusive);
391:
392: /**
393: * {@inheritDoc}
394: *
395: * <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}.
396: *
397: * @throws ClassCastException {@inheritDoc}
398: * @throws NullPointerException {@inheritDoc}
399: * @throws IllegalArgumentException {@inheritDoc}
400: */
401: SortedMap<K, V> subMap(K fromKey, K toKey);
402:
403: /**
404: * {@inheritDoc}
405: *
406: * <p>Equivalent to {@code headMap(toKey, false)}.
407: *
408: * @throws ClassCastException {@inheritDoc}
409: * @throws NullPointerException {@inheritDoc}
410: * @throws IllegalArgumentException {@inheritDoc}
411: */
412: SortedMap<K, V> headMap(K toKey);
413:
414: /**
415: * {@inheritDoc}
416: *
417: * <p>Equivalent to {@code tailMap(fromKey, true)}.
418: *
419: * @throws ClassCastException {@inheritDoc}
420: * @throws NullPointerException {@inheritDoc}
421: * @throws IllegalArgumentException {@inheritDoc}
422: */
423: SortedMap<K, V> tailMap(K fromKey);
424: }
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