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/publicdomain/zero/1.0/ |
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>Methods |
46 |
* {@link #subMap(Object, Object) subMap(K, K)}, |
47 |
* {@link #headMap(Object) headMap(K)}, and |
48 |
* {@link #tailMap(Object) tailMap(K)} |
49 |
* are specified to return {@code SortedMap} to allow existing |
50 |
* implementations of {@code SortedMap} to be compatibly retrofitted to |
51 |
* implement {@code NavigableMap}, but extensions and implementations |
52 |
* of this interface are encouraged to override these methods to return |
53 |
* {@code NavigableMap}. Similarly, |
54 |
* {@link #keySet()} can be overridden to return {@code NavigableSet}. |
55 |
* |
56 |
* <p>This interface is a member of the |
57 |
* <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
58 |
* Java Collections Framework</a>. |
59 |
* |
60 |
* @author Doug Lea |
61 |
* @author Josh Bloch |
62 |
* @param <K> the type of keys maintained by this map |
63 |
* @param <V> the type of mapped values |
64 |
* @since 1.6 |
65 |
*/ |
66 |
public interface NavigableMap<K,V> extends SortedMap<K,V> { |
67 |
/** |
68 |
* Returns a key-value mapping associated with the greatest key |
69 |
* strictly less than the given key, or {@code null} if there is |
70 |
* no such key. |
71 |
* |
72 |
* @param key the key |
73 |
* @return an entry with the greatest key less than {@code key}, |
74 |
* or {@code null} if there is no such key |
75 |
* @throws ClassCastException if the specified key cannot be compared |
76 |
* with the keys currently in the map |
77 |
* @throws NullPointerException if the specified key is null |
78 |
* and this map does not permit null keys |
79 |
*/ |
80 |
Map.Entry<K,V> lowerEntry(K key); |
81 |
|
82 |
/** |
83 |
* Returns the greatest key strictly less than the given key, or |
84 |
* {@code null} if there is no such key. |
85 |
* |
86 |
* @param key the key |
87 |
* @return the greatest key less than {@code key}, |
88 |
* or {@code null} if there is no such key |
89 |
* @throws ClassCastException if the specified key cannot be compared |
90 |
* with the keys currently in the map |
91 |
* @throws NullPointerException if the specified key is null |
92 |
* and this map does not permit null keys |
93 |
*/ |
94 |
K lowerKey(K key); |
95 |
|
96 |
/** |
97 |
* Returns a key-value mapping associated with the greatest key |
98 |
* less than or equal to the given key, or {@code null} if there |
99 |
* is no such key. |
100 |
* |
101 |
* @param key the key |
102 |
* @return an entry with the greatest key less than or equal to |
103 |
* {@code key}, 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> floorEntry(K key); |
110 |
|
111 |
/** |
112 |
* Returns the greatest key less than or equal to the given key, |
113 |
* or {@code null} if there is no such key. |
114 |
* |
115 |
* @param key the key |
116 |
* @return the greatest key less than or equal to {@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 floorKey(K key); |
124 |
|
125 |
/** |
126 |
* Returns a key-value mapping associated with the least key |
127 |
* greater than or equal to the given key, or {@code null} if |
128 |
* there is no such key. |
129 |
* |
130 |
* @param key the key |
131 |
* @return an entry with the least key greater 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> ceilingEntry(K key); |
139 |
|
140 |
/** |
141 |
* Returns the least key greater 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 least key greater 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 ceilingKey(K key); |
153 |
|
154 |
/** |
155 |
* Returns a key-value mapping associated with the least key |
156 |
* strictly greater than the given key, or {@code null} if there |
157 |
* is no such key. |
158 |
* |
159 |
* @param key the key |
160 |
* @return an entry with the least key greater than {@code key}, |
161 |
* 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> higherEntry(K key); |
168 |
|
169 |
/** |
170 |
* Returns the least key strictly greater than the given key, or |
171 |
* {@code null} if there is no such key. |
172 |
* |
173 |
* @param key the key |
174 |
* @return the least key greater than {@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 higherKey(K key); |
182 |
|
183 |
/** |
184 |
* Returns a key-value mapping associated with the least |
185 |
* key in this map, or {@code null} if the map is empty. |
186 |
* |
187 |
* @return an entry with the least key, |
188 |
* or {@code null} if this map is empty |
189 |
*/ |
190 |
Map.Entry<K,V> firstEntry(); |
191 |
|
192 |
/** |
193 |
* Returns a key-value mapping associated with the greatest |
194 |
* key in this map, or {@code null} if the map is empty. |
195 |
* |
196 |
* @return an entry with the greatest key, |
197 |
* or {@code null} if this map is empty |
198 |
*/ |
199 |
Map.Entry<K,V> lastEntry(); |
200 |
|
201 |
/** |
202 |
* Removes and returns a key-value mapping associated with |
203 |
* the least key in this map, or {@code null} if the map is empty. |
204 |
* |
205 |
* @return the removed first entry of this map, |
206 |
* or {@code null} if this map is empty |
207 |
*/ |
208 |
Map.Entry<K,V> pollFirstEntry(); |
209 |
|
210 |
/** |
211 |
* Removes and returns a key-value mapping associated with |
212 |
* the greatest key in this map, or {@code null} if the map is empty. |
213 |
* |
214 |
* @return the removed last entry of this map, |
215 |
* or {@code null} if this map is empty |
216 |
*/ |
217 |
Map.Entry<K,V> pollLastEntry(); |
218 |
|
219 |
/** |
220 |
* Returns a reverse order view of the mappings contained in this map. |
221 |
* The descending map is backed by this map, so changes to the map are |
222 |
* reflected in the descending map, and vice-versa. If either map is |
223 |
* modified while an iteration over a collection view of either map |
224 |
* is in progress (except through the iterator's own {@code remove} |
225 |
* operation), the results of the iteration are undefined. |
226 |
* |
227 |
* <p>The returned map has an ordering equivalent to |
228 |
* {@link Collections#reverseOrder(Comparator) Collections.reverseOrder}{@code (comparator())}. |
229 |
* The expression {@code m.descendingMap().descendingMap()} returns a |
230 |
* view of {@code m} essentially equivalent to {@code m}. |
231 |
* |
232 |
* @return a reverse order view of this map |
233 |
*/ |
234 |
NavigableMap<K,V> descendingMap(); |
235 |
|
236 |
/** |
237 |
* Returns a {@link NavigableSet} view of the keys contained in this map. |
238 |
* The set's iterator returns the keys in ascending order. |
239 |
* The set is backed by the map, so changes to the map are reflected in |
240 |
* the set, and vice-versa. If the map is modified while an iteration |
241 |
* over the set is in progress (except through the iterator's own {@code |
242 |
* remove} operation), the results of the iteration are undefined. The |
243 |
* set supports element removal, which removes the corresponding mapping |
244 |
* from the map, via the {@code Iterator.remove}, {@code Set.remove}, |
245 |
* {@code removeAll}, {@code retainAll}, and {@code clear} operations. |
246 |
* It does not support the {@code add} or {@code addAll} operations. |
247 |
* |
248 |
* @return a navigable set view of the keys in this map |
249 |
*/ |
250 |
NavigableSet<K> navigableKeySet(); |
251 |
|
252 |
/** |
253 |
* Returns a reverse order {@link NavigableSet} view of the keys contained in this map. |
254 |
* The set's iterator returns the keys in descending order. |
255 |
* The set is backed by the map, so changes to the map are reflected in |
256 |
* the set, and vice-versa. If the map is modified while an iteration |
257 |
* over the set is in progress (except through the iterator's own {@code |
258 |
* remove} operation), the results of the iteration are undefined. The |
259 |
* set supports element removal, which removes the corresponding mapping |
260 |
* from the map, via the {@code Iterator.remove}, {@code Set.remove}, |
261 |
* {@code removeAll}, {@code retainAll}, and {@code clear} operations. |
262 |
* It does not support the {@code add} or {@code addAll} operations. |
263 |
* |
264 |
* @return a reverse order navigable set view of the keys in this map |
265 |
*/ |
266 |
NavigableSet<K> descendingKeySet(); |
267 |
|
268 |
/** |
269 |
* Returns a view of the portion of this map whose keys range from |
270 |
* {@code fromKey} to {@code toKey}. If {@code fromKey} and |
271 |
* {@code toKey} are equal, the returned map is empty unless |
272 |
* {@code fromInclusive} and {@code toInclusive} are both true. The |
273 |
* returned map is backed by this map, so changes in the returned map are |
274 |
* reflected in this map, and vice-versa. The returned map supports all |
275 |
* optional map operations that this map supports. |
276 |
* |
277 |
* <p>The returned map will throw an {@code IllegalArgumentException} |
278 |
* on an attempt to insert a key outside of its range, or to construct a |
279 |
* submap either of whose endpoints lie outside its range. |
280 |
* |
281 |
* @param fromKey low endpoint of the keys in the returned map |
282 |
* @param fromInclusive {@code true} if the low endpoint |
283 |
* is to be included in the returned view |
284 |
* @param toKey high endpoint of the keys in the returned map |
285 |
* @param toInclusive {@code true} if the high endpoint |
286 |
* is to be included in the returned view |
287 |
* @return a view of the portion of this map whose keys range from |
288 |
* {@code fromKey} to {@code toKey} |
289 |
* @throws ClassCastException if {@code fromKey} and {@code toKey} |
290 |
* cannot be compared to one another using this map's comparator |
291 |
* (or, if the map has no comparator, using natural ordering). |
292 |
* Implementations may, but are not required to, throw this |
293 |
* exception if {@code fromKey} or {@code toKey} |
294 |
* cannot be compared to keys currently in the map. |
295 |
* @throws NullPointerException if {@code fromKey} or {@code toKey} |
296 |
* is null and this map does not permit null keys |
297 |
* @throws IllegalArgumentException if {@code fromKey} is greater than |
298 |
* {@code toKey}; or if this map itself has a restricted |
299 |
* range, and {@code fromKey} or {@code toKey} lies |
300 |
* outside the bounds of the range |
301 |
*/ |
302 |
NavigableMap<K,V> subMap(K fromKey, boolean fromInclusive, |
303 |
K toKey, boolean toInclusive); |
304 |
|
305 |
/** |
306 |
* Returns a view of the portion of this map whose keys are less than (or |
307 |
* equal to, if {@code inclusive} is true) {@code toKey}. The returned |
308 |
* map is backed by this map, so changes in the returned map are reflected |
309 |
* in this map, and vice-versa. The returned map supports all optional |
310 |
* map operations that this map supports. |
311 |
* |
312 |
* <p>The returned map will throw an {@code IllegalArgumentException} |
313 |
* on an attempt to insert a key outside its range. |
314 |
* |
315 |
* @param toKey high endpoint of the keys in the returned map |
316 |
* @param inclusive {@code true} if the high endpoint |
317 |
* is to be included in the returned view |
318 |
* @return a view of the portion of this map whose keys are less than |
319 |
* (or equal to, if {@code inclusive} is true) {@code toKey} |
320 |
* @throws ClassCastException if {@code toKey} is not compatible |
321 |
* with this map's comparator (or, if the map has no comparator, |
322 |
* if {@code toKey} does not implement {@link Comparable}). |
323 |
* Implementations may, but are not required to, throw this |
324 |
* exception if {@code toKey} cannot be compared to keys |
325 |
* currently in the map. |
326 |
* @throws NullPointerException if {@code toKey} is null |
327 |
* and this map does not permit null keys |
328 |
* @throws IllegalArgumentException if this map itself has a |
329 |
* restricted range, and {@code toKey} lies outside the |
330 |
* bounds of the range |
331 |
*/ |
332 |
NavigableMap<K,V> headMap(K toKey, boolean inclusive); |
333 |
|
334 |
/** |
335 |
* Returns a view of the portion of this map whose keys are greater than (or |
336 |
* equal to, if {@code inclusive} is true) {@code fromKey}. 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 fromKey low endpoint of the keys in the returned map |
345 |
* @param inclusive {@code true} if the low endpoint |
346 |
* is to be included in the returned view |
347 |
* @return a view of the portion of this map whose keys are greater than |
348 |
* (or equal to, if {@code inclusive} is true) {@code fromKey} |
349 |
* @throws ClassCastException if {@code fromKey} is not compatible |
350 |
* with this map's comparator (or, if the map has no comparator, |
351 |
* if {@code fromKey} does not implement {@link Comparable}). |
352 |
* Implementations may, but are not required to, throw this |
353 |
* exception if {@code fromKey} cannot be compared to keys |
354 |
* currently in the map. |
355 |
* @throws NullPointerException if {@code fromKey} 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 fromKey} lies outside the |
359 |
* bounds of the range |
360 |
*/ |
361 |
NavigableMap<K,V> tailMap(K fromKey, boolean inclusive); |
362 |
|
363 |
/** |
364 |
* {@inheritDoc} |
365 |
* |
366 |
* <p>Equivalent to {@code subMap(fromKey, true, toKey, false)}. |
367 |
* |
368 |
* @throws ClassCastException {@inheritDoc} |
369 |
* @throws NullPointerException {@inheritDoc} |
370 |
* @throws IllegalArgumentException {@inheritDoc} |
371 |
*/ |
372 |
SortedMap<K,V> subMap(K fromKey, K toKey); |
373 |
|
374 |
/** |
375 |
* {@inheritDoc} |
376 |
* |
377 |
* <p>Equivalent to {@code headMap(toKey, false)}. |
378 |
* |
379 |
* @throws ClassCastException {@inheritDoc} |
380 |
* @throws NullPointerException {@inheritDoc} |
381 |
* @throws IllegalArgumentException {@inheritDoc} |
382 |
*/ |
383 |
SortedMap<K,V> headMap(K toKey); |
384 |
|
385 |
/** |
386 |
* {@inheritDoc} |
387 |
* |
388 |
* <p>Equivalent to {@code tailMap(fromKey, true)}. |
389 |
* |
390 |
* @throws ClassCastException {@inheritDoc} |
391 |
* @throws NullPointerException {@inheritDoc} |
392 |
* @throws IllegalArgumentException {@inheritDoc} |
393 |
*/ |
394 |
SortedMap<K,V> tailMap(K fromKey); |
395 |
} |