Showing the changes to java/pkg/java/util/Set.java (1 of 18352 files). Show all
Unified · Split
| @@ -0,0 +1,385 @@ | |||
| 1 | /* | ||
| 2 | * Copyright (c) 1997, 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 collection that contains no duplicate elements. More formally, sets | ||
| 30 | * contain no pair of elements <code>e1</code> and <code>e2</code> such that | ||
| 31 | * <code>e1.equals(e2)</code>, and at most one null element. As implied by | ||
| 32 | * its name, this interface models the mathematical <i>set</i> abstraction. | ||
| 33 | * | ||
| 34 | * <p>The <tt>Set</tt> interface places additional stipulations, beyond those | ||
| 35 | * inherited from the <tt>Collection</tt> interface, on the contracts of all | ||
| 36 | * constructors and on the contracts of the <tt>add</tt>, <tt>equals</tt> and | ||
| 37 | * <tt>hashCode</tt> methods. Declarations for other inherited methods are | ||
| 38 | * also included here for convenience. (The specifications accompanying these | ||
| 39 | * declarations have been tailored to the <tt>Set</tt> interface, but they do | ||
| 40 | * not contain any additional stipulations.) | ||
| 41 | * | ||
| 42 | * <p>The additional stipulation on constructors is, not surprisingly, | ||
| 43 | * that all constructors must create a set that contains no duplicate elements | ||
| 44 | * (as defined above). | ||
| 45 | * | ||
| 46 | * <p>Note: Great care must be exercised if mutable objects are used as set | ||
| 47 | * elements. The behavior of a set is not specified if the value of an object | ||
| 48 | * is changed in a manner that affects <tt>equals</tt> comparisons while the | ||
| 49 | * object is an element in the set. A special case of this prohibition is | ||
| 50 | * that it is not permissible for a set to contain itself as an element. | ||
| 51 | * | ||
| 52 | * <p>Some set implementations have restrictions on the elements that | ||
| 53 | * they may contain. For example, some implementations prohibit null elements, | ||
| 54 | * and some have restrictions on the types of their elements. Attempting to | ||
| 55 | * add an ineligible element throws an unchecked exception, typically | ||
| 56 | * <tt>NullPointerException</tt> or <tt>ClassCastException</tt>. Attempting | ||
| 57 | * to query the presence of an ineligible element may throw an exception, | ||
| 58 | * or it may simply return false; some implementations will exhibit the former | ||
| 59 | * behavior and some will exhibit the latter. More generally, attempting an | ||
| 60 | * operation on an ineligible element whose completion would not result in | ||
| 61 | * the insertion of an ineligible element into the set may throw an | ||
| 62 | * exception or it may succeed, at the option of the implementation. | ||
| 63 | * Such exceptions are marked as "optional" in the specification for this | ||
| 64 | * interface. | ||
| 65 | * | ||
| 66 | * <p>This interface is a member of the | ||
| 67 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 68 | * Java Collections Framework</a>. | ||
| 69 | * | ||
| 70 | * @param <E> the type of elements maintained by this set | ||
| 71 | * | ||
| 72 | * @author Josh Bloch | ||
| 73 | * @author Neal Gafter | ||
| 74 | * @see Collection | ||
| 75 | * @see List | ||
| 76 | * @see SortedSet | ||
| 77 | * @see HashSet | ||
| 78 | * @see TreeSet | ||
| 79 | * @see AbstractSet | ||
| 80 | * @see Collections#singleton(java.lang.Object) | ||
| 81 | * @see Collections#EMPTY_SET | ||
| 82 | * @since 1.2 | ||
| 83 | */ | ||
| 84 | |||
| 85 | public interface Set<E> extends Collection<E> { | ||
| 86 | // Query Operations | ||
| 87 | |||
| 88 | /** | ||
| 89 | * Returns the number of elements in this set (its cardinality). If this | ||
| 90 | * set contains more than <tt>Integer.MAX_VALUE</tt> elements, returns | ||
| 91 | * <tt>Integer.MAX_VALUE</tt>. | ||
| 92 | * | ||
| 93 | * @return the number of elements in this set (its cardinality) | ||
| 94 | */ | ||
| 95 | int size(); | ||
| 96 | |||
| 97 | /** | ||
| 98 | * Returns <tt>true</tt> if this set contains no elements. | ||
| 99 | * | ||
| 100 | * @return <tt>true</tt> if this set contains no elements | ||
| 101 | */ | ||
| 102 | boolean isEmpty(); | ||
| 103 | |||
| 104 | /** | ||
| 105 | * Returns <tt>true</tt> if this set contains the specified element. | ||
| 106 | * More formally, returns <tt>true</tt> if and only if this set | ||
| 107 | * contains an element <tt>e</tt> such that | ||
| 108 | * <tt>(o==null ? e==null : o.equals(e))</tt>. | ||
| 109 | * | ||
| 110 | * @param o element whose presence in this set is to be tested | ||
| 111 | * @return <tt>true</tt> if this set contains the specified element | ||
| 112 | * @throws ClassCastException if the type of the specified element | ||
| 113 | * is incompatible with this set | ||
| 114 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 115 | * @throws NullPointerException if the specified element is null and this | ||
| 116 | * set does not permit null elements | ||
| 117 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 118 | */ | ||
| 119 | boolean contains(Object o); | ||
| 120 | |||
| 121 | /** | ||
| 122 | * Returns an iterator over the elements in this set. The elements are | ||
| 123 | * returned in no particular order (unless this set is an instance of some | ||
| 124 | * class that provides a guarantee). | ||
| 125 | * | ||
| 126 | * @return an iterator over the elements in this set | ||
| 127 | */ | ||
| 128 | Iterator<E> iterator(); | ||
| 129 | |||
| 130 | /** | ||
| 131 | * Returns an array containing all of the elements in this set. | ||
| 132 | * If this set makes any guarantees as to what order its elements | ||
| 133 | * are returned by its iterator, this method must return the | ||
| 134 | * elements in the same order. | ||
| 135 | * | ||
| 136 | * <p>The returned array will be "safe" in that no references to it | ||
| 137 | * are maintained by this set. (In other words, this method must | ||
| 138 | * allocate a new array even if this set is backed by an array). | ||
| 139 | * The caller is thus free to modify the returned array. | ||
| 140 | * | ||
| 141 | * <p>This method acts as bridge between array-based and collection-based | ||
| 142 | * APIs. | ||
| 143 | * | ||
| 144 | * @return an array containing all the elements in this set | ||
| 145 | */ | ||
| 146 | Object[] toArray(); | ||
| 147 | |||
| 148 | /** | ||
| 149 | * Returns an array containing all of the elements in this set; the | ||
| 150 | * runtime type of the returned array is that of the specified array. | ||
| 151 | * If the set fits in the specified array, it is returned therein. | ||
| 152 | * Otherwise, a new array is allocated with the runtime type of the | ||
| 153 | * specified array and the size of this set. | ||
| 154 | * | ||
| 155 | * <p>If this set fits in the specified array with room to spare | ||
| 156 | * (i.e., the array has more elements than this set), the element in | ||
| 157 | * the array immediately following the end of the set is set to | ||
| 158 | * <tt>null</tt>. (This is useful in determining the length of this | ||
| 159 | * set <i>only</i> if the caller knows that this set does not contain | ||
| 160 | * any null elements.) | ||
| 161 | * | ||
| 162 | * <p>If this set makes any guarantees as to what order its elements | ||
| 163 | * are returned by its iterator, this method must return the elements | ||
| 164 | * in the same order. | ||
| 165 | * | ||
| 166 | * <p>Like the {@link #toArray()} method, this method acts as bridge between | ||
| 167 | * array-based and collection-based APIs. Further, this method allows | ||
| 168 | * precise control over the runtime type of the output array, and may, | ||
| 169 | * under certain circumstances, be used to save allocation costs. | ||
| 170 | * | ||
| 171 | * <p>Suppose <tt>x</tt> is a set known to contain only strings. | ||
| 172 | * The following code can be used to dump the set into a newly allocated | ||
| 173 | * array of <tt>String</tt>: | ||
| 174 | * | ||
| 175 | * <pre> | ||
| 176 | * String[] y = x.toArray(new String[0]);</pre> | ||
| 177 | * | ||
| 178 | * Note that <tt>toArray(new Object[0])</tt> is identical in function to | ||
| 179 | * <tt>toArray()</tt>. | ||
| 180 | * | ||
| 181 | * @param a the array into which the elements of this set are to be | ||
| 182 | * stored, if it is big enough; otherwise, a new array of the same | ||
| 183 | * runtime type is allocated for this purpose. | ||
| 184 | * @return an array containing all the elements in this set | ||
| 185 | * @throws ArrayStoreException if the runtime type of the specified array | ||
| 186 | * is not a supertype of the runtime type of every element in this | ||
| 187 | * set | ||
| 188 | * @throws NullPointerException if the specified array is null | ||
| 189 | */ | ||
| 190 | <T> T[] toArray(T[] a); | ||
| 191 | |||
| 192 | |||
| 193 | // Modification Operations | ||
| 194 | |||
| 195 | /** | ||
| 196 | * Adds the specified element to this set if it is not already present | ||
| 197 | * (optional operation). More formally, adds the specified element | ||
| 198 | * <tt>e</tt> to this set if the set contains no element <tt>e2</tt> | ||
| 199 | * such that | ||
| 200 | * <tt>(e==null ? e2==null : e.equals(e2))</tt>. | ||
| 201 | * If this set already contains the element, the call leaves the set | ||
| 202 | * unchanged and returns <tt>false</tt>. In combination with the | ||
| 203 | * restriction on constructors, this ensures that sets never contain | ||
| 204 | * duplicate elements. | ||
| 205 | * | ||
| 206 | * <p>The stipulation above does not imply that sets must accept all | ||
| 207 | * elements; sets may refuse to add any particular element, including | ||
| 208 | * <tt>null</tt>, and throw an exception, as described in the | ||
| 209 | * specification for {@link Collection#add Collection.add}. | ||
| 210 | * Individual set implementations should clearly document any | ||
| 211 | * restrictions on the elements that they may contain. | ||
| 212 | * | ||
| 213 | * @param e element to be added to this set | ||
| 214 | * @return <tt>true</tt> if this set did not already contain the specified | ||
| 215 | * element | ||
| 216 | * @throws UnsupportedOperationException if the <tt>add</tt> operation | ||
| 217 | * is not supported by this set | ||
| 218 | * @throws ClassCastException if the class of the specified element | ||
| 219 | * prevents it from being added to this set | ||
| 220 | * @throws NullPointerException if the specified element is null and this | ||
| 221 | * set does not permit null elements | ||
| 222 | * @throws IllegalArgumentException if some property of the specified element | ||
| 223 | * prevents it from being added to this set | ||
| 224 | */ | ||
| 225 | boolean add(E e); | ||
| 226 | |||
| 227 | |||
| 228 | /** | ||
| 229 | * Removes the specified element from this set if it is present | ||
| 230 | * (optional operation). More formally, removes an element <tt>e</tt> | ||
| 231 | * such that | ||
| 232 | * <tt>(o==null ? e==null : o.equals(e))</tt>, if | ||
| 233 | * this set contains such an element. Returns <tt>true</tt> if this set | ||
| 234 | * contained the element (or equivalently, if this set changed as a | ||
| 235 | * result of the call). (This set will not contain the element once the | ||
| 236 | * call returns.) | ||
| 237 | * | ||
| 238 | * @param o object to be removed from this set, if present | ||
| 239 | * @return <tt>true</tt> if this set contained the specified element | ||
| 240 | * @throws ClassCastException if the type of the specified element | ||
| 241 | * is incompatible with this set | ||
| 242 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 243 | * @throws NullPointerException if the specified element is null and this | ||
| 244 | * set does not permit null elements | ||
| 245 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 246 | * @throws UnsupportedOperationException if the <tt>remove</tt> operation | ||
| 247 | * is not supported by this set | ||
| 248 | */ | ||
| 249 | boolean remove(Object o); | ||
| 250 | |||
| 251 | |||
| 252 | // Bulk Operations | ||
| 253 | |||
| 254 | /** | ||
| 255 | * Returns <tt>true</tt> if this set contains all of the elements of the | ||
| 256 | * specified collection. If the specified collection is also a set, this | ||
| 257 | * method returns <tt>true</tt> if it is a <i>subset</i> of this set. | ||
| 258 | * | ||
| 259 | * @param c collection to be checked for containment in this set | ||
| 260 | * @return <tt>true</tt> if this set contains all of the elements of the | ||
| 261 | * specified collection | ||
| 262 | * @throws ClassCastException if the types of one or more elements | ||
| 263 | * in the specified collection are incompatible with this | ||
| 264 | * set | ||
| 265 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 266 | * @throws NullPointerException if the specified collection contains one | ||
| 267 | * or more null elements and this set does not permit null | ||
| 268 | * elements | ||
| 269 | * (<a href="Collection.html#optional-restrictions">optional</a>), | ||
| 270 | * or if the specified collection is null | ||
| 271 | * @see #contains(Object) | ||
| 272 | */ | ||
| 273 | boolean containsAll(Collection<?> c); | ||
| 274 | |||
| 275 | /** | ||
| 276 | * Adds all of the elements in the specified collection to this set if | ||
| 277 | * they're not already present (optional operation). If the specified | ||
| 278 | * collection is also a set, the <tt>addAll</tt> operation effectively | ||
| 279 | * modifies this set so that its value is the <i>union</i> of the two | ||
| 280 | * sets. The behavior of this operation is undefined if the specified | ||
| 281 | * collection is modified while the operation is in progress. | ||
| 282 | * | ||
| 283 | * @param c collection containing elements to be added to this set | ||
| 284 | * @return <tt>true</tt> if this set changed as a result of the call | ||
| 285 | * | ||
| 286 | * @throws UnsupportedOperationException if the <tt>addAll</tt> operation | ||
| 287 | * is not supported by this set | ||
| 288 | * @throws ClassCastException if the class of an element of the | ||
| 289 | * specified collection prevents it from being added to this set | ||
| 290 | * @throws NullPointerException if the specified collection contains one | ||
| 291 | * or more null elements and this set does not permit null | ||
| 292 | * elements, or if the specified collection is null | ||
| 293 | * @throws IllegalArgumentException if some property of an element of the | ||
| 294 | * specified collection prevents it from being added to this set | ||
| 295 | * @see #add(Object) | ||
| 296 | */ | ||
| 297 | boolean addAll(Collection<? extends E> c); | ||
| 298 | |||
| 299 | /** | ||
| 300 | * Retains only the elements in this set that are contained in the | ||
| 301 | * specified collection (optional operation). In other words, removes | ||
| 302 | * from this set all of its elements that are not contained in the | ||
| 303 | * specified collection. If the specified collection is also a set, this | ||
| 304 | * operation effectively modifies this set so that its value is the | ||
| 305 | * <i>intersection</i> of the two sets. | ||
| 306 | * | ||
| 307 | * @param c collection containing elements to be retained in this set | ||
| 308 | * @return <tt>true</tt> if this set changed as a result of the call | ||
| 309 | * @throws UnsupportedOperationException if the <tt>retainAll</tt> operation | ||
| 310 | * is not supported by this set | ||
| 311 | * @throws ClassCastException if the class of an element of this set | ||
| 312 | * is incompatible with the specified collection | ||
| 313 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 314 | * @throws NullPointerException if this set contains a null element and the | ||
| 315 | * specified collection does not permit null elements | ||
| 316 | * (<a href="Collection.html#optional-restrictions">optional</a>), | ||
| 317 | * or if the specified collection is null | ||
| 318 | * @see #remove(Object) | ||
| 319 | */ | ||
| 320 | boolean retainAll(Collection<?> c); | ||
| 321 | |||
| 322 | /** | ||
| 323 | * Removes from this set all of its elements that are contained in the | ||
| 324 | * specified collection (optional operation). If the specified | ||
| 325 | * collection is also a set, this operation effectively modifies this | ||
| 326 | * set so that its value is the <i>asymmetric set difference</i> of | ||
| 327 | * the two sets. | ||
| 328 | * | ||
| 329 | * @param c collection containing elements to be removed from this set | ||
| 330 | * @return <tt>true</tt> if this set changed as a result of the call | ||
| 331 | * @throws UnsupportedOperationException if the <tt>removeAll</tt> operation | ||
| 332 | * is not supported by this set | ||
| 333 | * @throws ClassCastException if the class of an element of this set | ||
| 334 | * is incompatible with the specified collection | ||
| 335 | * (<a href="Collection.html#optional-restrictions">optional</a>) | ||
| 336 | * @throws NullPointerException if this set contains a null element and the | ||
| 337 | * specified collection does not permit null elements | ||
| 338 | * (<a href="Collection.html#optional-restrictions">optional</a>), | ||
| 339 | * or if the specified collection is null | ||
| 340 | * @see #remove(Object) | ||
| 341 | * @see #contains(Object) | ||
| 342 | */ | ||
| 343 | boolean removeAll(Collection<?> c); | ||
| 344 | |||
| 345 | /** | ||
| 346 | * Removes all of the elements from this set (optional operation). | ||
| 347 | * The set will be empty after this call returns. | ||
| 348 | * | ||
| 349 | * @throws UnsupportedOperationException if the <tt>clear</tt> method | ||
| 350 | * is not supported by this set | ||
| 351 | */ | ||
| 352 | void clear(); | ||
| 353 | |||
| 354 | |||
| 355 | // Comparison and hashing | ||
| 356 | |||
| 357 | /** | ||
| 358 | * Compares the specified object with this set for equality. Returns | ||
| 359 | * <tt>true</tt> if the specified object is also a set, the two sets | ||
| 360 | * have the same size, and every member of the specified set is | ||
| 361 | * contained in this set (or equivalently, every member of this set is | ||
| 362 | * contained in the specified set). This definition ensures that the | ||
| 363 | * equals method works properly across different implementations of the | ||
| 364 | * set interface. | ||
| 365 | * | ||
| 366 | * @param o object to be compared for equality with this set | ||
| 367 | * @return <tt>true</tt> if the specified object is equal to this set | ||
| 368 | */ | ||
| 369 | boolean equals(Object o); | ||
| 370 | |||
| 371 | /** | ||
| 372 | * Returns the hash code value for this set. The hash code of a set is | ||
| 373 | * defined to be the sum of the hash codes of the elements in the set, | ||
| 374 | * where the hash code of a <tt>null</tt> element is defined to be zero. | ||
| 375 | * This ensures that <tt>s1.equals(s2)</tt> implies that | ||
| 376 | * <tt>s1.hashCode()==s2.hashCode()</tt> for any two sets <tt>s1</tt> | ||
| 377 | * and <tt>s2</tt>, as required by the general contract of | ||
| 378 | * {@link Object#hashCode}. | ||
| 379 | * | ||
| 380 | * @return the hash code value for this set | ||
| 381 | * @see Object#equals(Object) | ||
| 382 | * @see Set#equals(Object) | ||
| 383 | */ | ||
| 384 | int hashCode(); | ||
| 385 | } | ||