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| 1 | /* | ||
| 2 | * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.util; | ||
| 27 | |||
| 28 | /** | ||
| 29 | * A {@link Map} that further provides a <em>total ordering</em> on its keys. | ||
| 30 | * The map is ordered according to the {@linkplain Comparable natural | ||
| 31 | * ordering} of its keys, or by a {@link Comparator} typically | ||
| 32 | * provided at sorted map creation time. This order is reflected when | ||
| 33 | * iterating over the sorted map's collection views (returned by the | ||
| 34 | * {@code entrySet}, {@code keySet} and {@code values} methods). | ||
| 35 | * Several additional operations are provided to take advantage of the | ||
| 36 | * ordering. (This interface is the map analogue of {@link SortedSet}.) | ||
| 37 | * | ||
| 38 | * <p>All keys inserted into a sorted map must implement the {@code Comparable} | ||
| 39 | * interface (or be accepted by the specified comparator). Furthermore, all | ||
| 40 | * such keys must be <em>mutually comparable</em>: {@code k1.compareTo(k2)} (or | ||
| 41 | * {@code comparator.compare(k1, k2)}) must not throw a | ||
| 42 | * {@code ClassCastException} for any keys {@code k1} and {@code k2} in | ||
| 43 | * the sorted map. Attempts to violate this restriction will cause the | ||
| 44 | * offending method or constructor invocation to throw a | ||
| 45 | * {@code ClassCastException}. | ||
| 46 | * | ||
| 47 | * <p>Note that the ordering maintained by a sorted map (whether or not an | ||
| 48 | * explicit comparator is provided) must be <em>consistent with equals</em> if | ||
| 49 | * the sorted map is to correctly implement the {@code Map} interface. (See | ||
| 50 | * the {@code Comparable} interface or {@code Comparator} interface for a | ||
| 51 | * precise definition of <em>consistent with equals</em>.) This is so because | ||
| 52 | * the {@code Map} interface is defined in terms of the {@code equals} | ||
| 53 | * operation, but a sorted map performs all key comparisons using its | ||
| 54 | * {@code compareTo} (or {@code compare}) method, so two keys that are | ||
| 55 | * deemed equal by this method are, from the standpoint of the sorted map, | ||
| 56 | * equal. The behavior of a tree map <em>is</em> well-defined even if its | ||
| 57 | * ordering is inconsistent with equals; it just fails to obey the general | ||
| 58 | * contract of the {@code Map} interface. | ||
| 59 | * | ||
| 60 | * <p>All general-purpose sorted map implementation classes should provide four | ||
| 61 | * "standard" constructors. It is not possible to enforce this recommendation | ||
| 62 | * though as required constructors cannot be specified by interfaces. The | ||
| 63 | * expected "standard" constructors for all sorted map implementations are: | ||
| 64 | * <ol> | ||
| 65 | * <li>A void (no arguments) constructor, which creates an empty sorted map | ||
| 66 | * sorted according to the natural ordering of its keys.</li> | ||
| 67 | * <li>A constructor with a single argument of type {@code Comparator}, which | ||
| 68 | * creates an empty sorted map sorted according to the specified comparator.</li> | ||
| 69 | * <li>A constructor with a single argument of type {@code Map}, which creates | ||
| 70 | * a new map with the same key-value mappings as its argument, sorted | ||
| 71 | * according to the keys' natural ordering.</li> | ||
| 72 | * <li>A constructor with a single argument of type {@code SortedMap}, which | ||
| 73 | * creates a new sorted map with the same key-value mappings and the same | ||
| 74 | * ordering as the input sorted map.</li> | ||
| 75 | * </ol> | ||
| 76 | * | ||
| 77 | * <p><strong>Note</strong>: several methods return submaps with restricted key | ||
| 78 | * ranges. Such ranges are <em>half-open</em>, that is, they include their low | ||
| 79 | * endpoint but not their high endpoint (where applicable). If you need a | ||
| 80 | * <em>closed range</em> (which includes both endpoints), and the key type | ||
| 81 | * allows for calculation of the successor of a given key, merely request | ||
| 82 | * the subrange from {@code lowEndpoint} to | ||
| 83 | * {@code successor(highEndpoint)}. For example, suppose that {@code m} | ||
| 84 | * is a map whose keys are strings. The following idiom obtains a view | ||
| 85 | * containing all of the key-value mappings in {@code m} whose keys are | ||
| 86 | * between {@code low} and {@code high}, inclusive:<pre> | ||
| 87 | * SortedMap<String, V> sub = m.subMap(low, high+"\0");</pre> | ||
| 88 | * | ||
| 89 | * A similar technique can be used to generate an <em>open range</em> | ||
| 90 | * (which contains neither endpoint). The following idiom obtains a | ||
| 91 | * view containing all of the key-value mappings in {@code m} whose keys | ||
| 92 | * are between {@code low} and {@code high}, exclusive:<pre> | ||
| 93 | * SortedMap<String, V> sub = m.subMap(low+"\0", high);</pre> | ||
| 94 | * | ||
| 95 | * <p>This interface is a member of the | ||
| 96 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 97 | * Java Collections Framework</a>. | ||
| 98 | * | ||
| 99 | * @param <K> the type of keys maintained by this map | ||
| 100 | * @param <V> the type of mapped values | ||
| 101 | * | ||
| 102 | * @author Josh Bloch | ||
| 103 | * @see Map | ||
| 104 | * @see TreeMap | ||
| 105 | * @see SortedSet | ||
| 106 | * @see Comparator | ||
| 107 | * @see Comparable | ||
| 108 | * @see Collection | ||
| 109 | * @see ClassCastException | ||
| 110 | * @since 1.2 | ||
| 111 | */ | ||
| 112 | |||
| 113 | public interface SortedMap<K,V> extends Map<K,V> { | ||
| 114 | /** | ||
| 115 | * Returns the comparator used to order the keys in this map, or | ||
| 116 | * {@code null} if this map uses the {@linkplain Comparable | ||
| 117 | * natural ordering} of its keys. | ||
| 118 | * | ||
| 119 | * @return the comparator used to order the keys in this map, | ||
| 120 | * or {@code null} if this map uses the natural ordering | ||
| 121 | * of its keys | ||
| 122 | */ | ||
| 123 | Comparator<? super K> comparator(); | ||
| 124 | |||
| 125 | /** | ||
| 126 | * Returns a view of the portion of this map whose keys range from | ||
| 127 | * {@code fromKey}, inclusive, to {@code toKey}, exclusive. (If | ||
| 128 | * {@code fromKey} and {@code toKey} are equal, the returned map | ||
| 129 | * is empty.) The returned map is backed by this map, so changes | ||
| 130 | * in the returned map are reflected in this map, and vice-versa. | ||
| 131 | * The returned map supports all optional map operations that this | ||
| 132 | * map supports. | ||
| 133 | * | ||
| 134 | * <p>The returned map will throw an {@code IllegalArgumentException} | ||
| 135 | * on an attempt to insert a key outside its range. | ||
| 136 | * | ||
| 137 | * @param fromKey low endpoint (inclusive) of the keys in the returned map | ||
| 138 | * @param toKey high endpoint (exclusive) of the keys in the returned map | ||
| 139 | * @return a view of the portion of this map whose keys range from | ||
| 140 | * {@code fromKey}, inclusive, to {@code toKey}, exclusive | ||
| 141 | * @throws ClassCastException if {@code fromKey} and {@code toKey} | ||
| 142 | * cannot be compared to one another using this map's comparator | ||
| 143 | * (or, if the map has no comparator, using natural ordering). | ||
| 144 | * Implementations may, but are not required to, throw this | ||
| 145 | * exception if {@code fromKey} or {@code toKey} | ||
| 146 | * cannot be compared to keys currently in the map. | ||
| 147 | * @throws NullPointerException if {@code fromKey} or {@code toKey} | ||
| 148 | * is null and this map does not permit null keys | ||
| 149 | * @throws IllegalArgumentException if {@code fromKey} is greater than | ||
| 150 | * {@code toKey}; or if this map itself has a restricted | ||
| 151 | * range, and {@code fromKey} or {@code toKey} lies | ||
| 152 | * outside the bounds of the range | ||
| 153 | */ | ||
| 154 | SortedMap<K,V> subMap(K fromKey, K toKey); | ||
| 155 | |||
| 156 | /** | ||
| 157 | * Returns a view of the portion of this map whose keys are | ||
| 158 | * strictly less than {@code toKey}. The returned map is backed | ||
| 159 | * by this map, so changes in the returned map are reflected in | ||
| 160 | * this map, and vice-versa. The returned map supports all | ||
| 161 | * optional map operations that this map supports. | ||
| 162 | * | ||
| 163 | * <p>The returned map will throw an {@code IllegalArgumentException} | ||
| 164 | * on an attempt to insert a key outside its range. | ||
| 165 | * | ||
| 166 | * @param toKey high endpoint (exclusive) of the keys in the returned map | ||
| 167 | * @return a view of the portion of this map whose keys are strictly | ||
| 168 | * less than {@code toKey} | ||
| 169 | * @throws ClassCastException if {@code toKey} is not compatible | ||
| 170 | * with this map's comparator (or, if the map has no comparator, | ||
| 171 | * if {@code toKey} does not implement {@link Comparable}). | ||
| 172 | * Implementations may, but are not required to, throw this | ||
| 173 | * exception if {@code toKey} cannot be compared to keys | ||
| 174 | * currently in the map. | ||
| 175 | * @throws NullPointerException if {@code toKey} is null and | ||
| 176 | * this map does not permit null keys | ||
| 177 | * @throws IllegalArgumentException if this map itself has a | ||
| 178 | * restricted range, and {@code toKey} lies outside the | ||
| 179 | * bounds of the range | ||
| 180 | */ | ||
| 181 | SortedMap<K,V> headMap(K toKey); | ||
| 182 | |||
| 183 | /** | ||
| 184 | * Returns a view of the portion of this map whose keys are | ||
| 185 | * greater than or equal to {@code fromKey}. The returned map is | ||
| 186 | * backed by this map, so changes in the returned map are | ||
| 187 | * reflected in this map, and vice-versa. The returned map | ||
| 188 | * supports all optional map operations that this map supports. | ||
| 189 | * | ||
| 190 | * <p>The returned map will throw an {@code IllegalArgumentException} | ||
| 191 | * on an attempt to insert a key outside its range. | ||
| 192 | * | ||
| 193 | * @param fromKey low endpoint (inclusive) of the keys in the returned map | ||
| 194 | * @return a view of the portion of this map whose keys are greater | ||
| 195 | * than or equal to {@code fromKey} | ||
| 196 | * @throws ClassCastException if {@code fromKey} is not compatible | ||
| 197 | * with this map's comparator (or, if the map has no comparator, | ||
| 198 | * if {@code fromKey} does not implement {@link Comparable}). | ||
| 199 | * Implementations may, but are not required to, throw this | ||
| 200 | * exception if {@code fromKey} cannot be compared to keys | ||
| 201 | * currently in the map. | ||
| 202 | * @throws NullPointerException if {@code fromKey} is null and | ||
| 203 | * this map does not permit null keys | ||
| 204 | * @throws IllegalArgumentException if this map itself has a | ||
| 205 | * restricted range, and {@code fromKey} lies outside the | ||
| 206 | * bounds of the range | ||
| 207 | */ | ||
| 208 | SortedMap<K,V> tailMap(K fromKey); | ||
| 209 | |||
| 210 | /** | ||
| 211 | * Returns the first (lowest) key currently in this map. | ||
| 212 | * | ||
| 213 | * @return the first (lowest) key currently in this map | ||
| 214 | * @throws NoSuchElementException if this map is empty | ||
| 215 | */ | ||
| 216 | K firstKey(); | ||
| 217 | |||
| 218 | /** | ||
| 219 | * Returns the last (highest) key currently in this map. | ||
| 220 | * | ||
| 221 | * @return the last (highest) key currently in this map | ||
| 222 | * @throws NoSuchElementException if this map is empty | ||
| 223 | */ | ||
| 224 | K lastKey(); | ||
| 225 | |||
| 226 | /** | ||
| 227 | * Returns a {@link Set} view of the keys contained in this map. | ||
| 228 | * The set's iterator returns the keys in ascending order. | ||
| 229 | * The set is backed by the map, so changes to the map are | ||
| 230 | * reflected in the set, and vice-versa. If the map is modified | ||
| 231 | * while an iteration over the set is in progress (except through | ||
| 232 | * the iterator's own {@code remove} operation), the results of | ||
| 233 | * the iteration are undefined. The set supports element removal, | ||
| 234 | * which removes the corresponding mapping from the map, via the | ||
| 235 | * {@code Iterator.remove}, {@code Set.remove}, | ||
| 236 | * {@code removeAll}, {@code retainAll}, and {@code clear} | ||
| 237 | * operations. It does not support the {@code add} or {@code addAll} | ||
| 238 | * operations. | ||
| 239 | * | ||
| 240 | * @return a set view of the keys contained in this map, sorted in | ||
| 241 | * ascending order | ||
| 242 | */ | ||
| 243 | Set<K> keySet(); | ||
| 244 | |||
| 245 | /** | ||
| 246 | * Returns a {@link Collection} view of the values contained in this map. | ||
| 247 | * The collection's iterator returns the values in ascending order | ||
| 248 | * of the corresponding keys. | ||
| 249 | * The collection is backed by the map, so changes to the map are | ||
| 250 | * reflected in the collection, and vice-versa. If the map is | ||
| 251 | * modified while an iteration over the collection is in progress | ||
| 252 | * (except through the iterator's own {@code remove} operation), | ||
| 253 | * the results of the iteration are undefined. The collection | ||
| 254 | * supports element removal, which removes the corresponding | ||
| 255 | * mapping from the map, via the {@code Iterator.remove}, | ||
| 256 | * {@code Collection.remove}, {@code removeAll}, | ||
| 257 | * {@code retainAll} and {@code clear} operations. It does not | ||
| 258 | * support the {@code add} or {@code addAll} operations. | ||
| 259 | * | ||
| 260 | * @return a collection view of the values contained in this map, | ||
| 261 | * sorted in ascending key order | ||
| 262 | */ | ||
| 263 | Collection<V> values(); | ||
| 264 | |||
| 265 | /** | ||
| 266 | * Returns a {@link Set} view of the mappings contained in this map. | ||
| 267 | * The set's iterator returns the entries in ascending key order. | ||
| 268 | * The set is backed by the map, so changes to the map are | ||
| 269 | * reflected in the set, and vice-versa. If the map is modified | ||
| 270 | * while an iteration over the set is in progress (except through | ||
| 271 | * the iterator's own {@code remove} operation, or through the | ||
| 272 | * {@code setValue} operation on a map entry returned by the | ||
| 273 | * iterator) the results of the iteration are undefined. The set | ||
| 274 | * supports element removal, which removes the corresponding | ||
| 275 | * mapping from the map, via the {@code Iterator.remove}, | ||
| 276 | * {@code Set.remove}, {@code removeAll}, {@code retainAll} and | ||
| 277 | * {@code clear} operations. It does not support the | ||
| 278 | * {@code add} or {@code addAll} operations. | ||
| 279 | * | ||
| 280 | * @return a set view of the mappings contained in this map, | ||
| 281 | * sorted in ascending key order | ||
| 282 | */ | ||
| 283 | Set<Map.Entry<K, V>> entrySet(); | ||
| 284 | } | ||