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| 1 | /* | ||
| 2 | * Copyright (c) 1997, 2010, 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 | import java.util.Map.Entry; | ||
| 28 | |||
| 29 | /** | ||
| 30 | * This class provides a skeletal implementation of the <tt>Map</tt> | ||
| 31 | * interface, to minimize the effort required to implement this interface. | ||
| 32 | * | ||
| 33 | * <p>To implement an unmodifiable map, the programmer needs only to extend this | ||
| 34 | * class and provide an implementation for the <tt>entrySet</tt> method, which | ||
| 35 | * returns a set-view of the map's mappings. Typically, the returned set | ||
| 36 | * will, in turn, be implemented atop <tt>AbstractSet</tt>. This set should | ||
| 37 | * not support the <tt>add</tt> or <tt>remove</tt> methods, and its iterator | ||
| 38 | * should not support the <tt>remove</tt> method. | ||
| 39 | * | ||
| 40 | * <p>To implement a modifiable map, the programmer must additionally override | ||
| 41 | * this class's <tt>put</tt> method (which otherwise throws an | ||
| 42 | * <tt>UnsupportedOperationException</tt>), and the iterator returned by | ||
| 43 | * <tt>entrySet().iterator()</tt> must additionally implement its | ||
| 44 | * <tt>remove</tt> method. | ||
| 45 | * | ||
| 46 | * <p>The programmer should generally provide a void (no argument) and map | ||
| 47 | * constructor, as per the recommendation in the <tt>Map</tt> interface | ||
| 48 | * specification. | ||
| 49 | * | ||
| 50 | * <p>The documentation for each non-abstract method in this class describes its | ||
| 51 | * implementation in detail. Each of these methods may be overridden if the | ||
| 52 | * map being implemented admits a more efficient implementation. | ||
| 53 | * | ||
| 54 | * <p>This class is a member of the | ||
| 55 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> | ||
| 56 | * Java Collections Framework</a>. | ||
| 57 | * | ||
| 58 | * @param <K> the type of keys maintained by this map | ||
| 59 | * @param <V> the type of mapped values | ||
| 60 | * | ||
| 61 | * @author Josh Bloch | ||
| 62 | * @author Neal Gafter | ||
| 63 | * @see Map | ||
| 64 | * @see Collection | ||
| 65 | * @since 1.2 | ||
| 66 | */ | ||
| 67 | |||
| 68 | public abstract class AbstractMap<K,V> implements Map<K,V> { | ||
| 69 | /** | ||
| 70 | * Sole constructor. (For invocation by subclass constructors, typically | ||
| 71 | * implicit.) | ||
| 72 | */ | ||
| 73 | protected AbstractMap() { | ||
| 74 | } | ||
| 75 | |||
| 76 | // Query Operations | ||
| 77 | |||
| 78 | /** | ||
| 79 | * {@inheritDoc} | ||
| 80 | * | ||
| 81 | * <p>This implementation returns <tt>entrySet().size()</tt>. | ||
| 82 | */ | ||
| 83 | public int size() { | ||
| 84 | return entrySet().size(); | ||
| 85 | } | ||
| 86 | |||
| 87 | /** | ||
| 88 | * {@inheritDoc} | ||
| 89 | * | ||
| 90 | * <p>This implementation returns <tt>size() == 0</tt>. | ||
| 91 | */ | ||
| 92 | public boolean isEmpty() { | ||
| 93 | return size() == 0; | ||
| 94 | } | ||
| 95 | |||
| 96 | /** | ||
| 97 | * {@inheritDoc} | ||
| 98 | * | ||
| 99 | * <p>This implementation iterates over <tt>entrySet()</tt> searching | ||
| 100 | * for an entry with the specified value. If such an entry is found, | ||
| 101 | * <tt>true</tt> is returned. If the iteration terminates without | ||
| 102 | * finding such an entry, <tt>false</tt> is returned. Note that this | ||
| 103 | * implementation requires linear time in the size of the map. | ||
| 104 | * | ||
| 105 | * @throws ClassCastException {@inheritDoc} | ||
| 106 | * @throws NullPointerException {@inheritDoc} | ||
| 107 | */ | ||
| 108 | public boolean containsValue(Object value) { | ||
| 109 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 110 | if (value==null) { | ||
| 111 | while (i.hasNext()) { | ||
| 112 | Entry<K,V> e = i.next(); | ||
| 113 | if (e.getValue()==null) | ||
| 114 | return true; | ||
| 115 | } | ||
| 116 | } else { | ||
| 117 | while (i.hasNext()) { | ||
| 118 | Entry<K,V> e = i.next(); | ||
| 119 | if (value.equals(e.getValue())) | ||
| 120 | return true; | ||
| 121 | } | ||
| 122 | } | ||
| 123 | return false; | ||
| 124 | } | ||
| 125 | |||
| 126 | /** | ||
| 127 | * {@inheritDoc} | ||
| 128 | * | ||
| 129 | * <p>This implementation iterates over <tt>entrySet()</tt> searching | ||
| 130 | * for an entry with the specified key. If such an entry is found, | ||
| 131 | * <tt>true</tt> is returned. If the iteration terminates without | ||
| 132 | * finding such an entry, <tt>false</tt> is returned. Note that this | ||
| 133 | * implementation requires linear time in the size of the map; many | ||
| 134 | * implementations will override this method. | ||
| 135 | * | ||
| 136 | * @throws ClassCastException {@inheritDoc} | ||
| 137 | * @throws NullPointerException {@inheritDoc} | ||
| 138 | */ | ||
| 139 | public boolean containsKey(Object key) { | ||
| 140 | Iterator<Map.Entry<K,V>> i = entrySet().iterator(); | ||
| 141 | if (key==null) { | ||
| 142 | while (i.hasNext()) { | ||
| 143 | Entry<K,V> e = i.next(); | ||
| 144 | if (e.getKey()==null) | ||
| 145 | return true; | ||
| 146 | } | ||
| 147 | } else { | ||
| 148 | while (i.hasNext()) { | ||
| 149 | Entry<K,V> e = i.next(); | ||
| 150 | if (key.equals(e.getKey())) | ||
| 151 | return true; | ||
| 152 | } | ||
| 153 | } | ||
| 154 | return false; | ||
| 155 | } | ||
| 156 | |||
| 157 | /** | ||
| 158 | * {@inheritDoc} | ||
| 159 | * | ||
| 160 | * <p>This implementation iterates over <tt>entrySet()</tt> searching | ||
| 161 | * for an entry with the specified key. If such an entry is found, | ||
| 162 | * the entry's value is returned. If the iteration terminates without | ||
| 163 | * finding such an entry, <tt>null</tt> is returned. Note that this | ||
| 164 | * implementation requires linear time in the size of the map; many | ||
| 165 | * implementations will override this method. | ||
| 166 | * | ||
| 167 | * @throws ClassCastException {@inheritDoc} | ||
| 168 | * @throws NullPointerException {@inheritDoc} | ||
| 169 | */ | ||
| 170 | public V get(Object key) { | ||
| 171 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 172 | if (key==null) { | ||
| 173 | while (i.hasNext()) { | ||
| 174 | Entry<K,V> e = i.next(); | ||
| 175 | if (e.getKey()==null) | ||
| 176 | return e.getValue(); | ||
| 177 | } | ||
| 178 | } else { | ||
| 179 | while (i.hasNext()) { | ||
| 180 | Entry<K,V> e = i.next(); | ||
| 181 | if (key.equals(e.getKey())) | ||
| 182 | return e.getValue(); | ||
| 183 | } | ||
| 184 | } | ||
| 185 | return null; | ||
| 186 | } | ||
| 187 | |||
| 188 | |||
| 189 | // Modification Operations | ||
| 190 | |||
| 191 | /** | ||
| 192 | * {@inheritDoc} | ||
| 193 | * | ||
| 194 | * <p>This implementation always throws an | ||
| 195 | * <tt>UnsupportedOperationException</tt>. | ||
| 196 | * | ||
| 197 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 198 | * @throws ClassCastException {@inheritDoc} | ||
| 199 | * @throws NullPointerException {@inheritDoc} | ||
| 200 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 201 | */ | ||
| 202 | public V put(K key, V value) { | ||
| 203 | throw new UnsupportedOperationException(); | ||
| 204 | } | ||
| 205 | |||
| 206 | /** | ||
| 207 | * {@inheritDoc} | ||
| 208 | * | ||
| 209 | * <p>This implementation iterates over <tt>entrySet()</tt> searching for an | ||
| 210 | * entry with the specified key. If such an entry is found, its value is | ||
| 211 | * obtained with its <tt>getValue</tt> operation, the entry is removed | ||
| 212 | * from the collection (and the backing map) with the iterator's | ||
| 213 | * <tt>remove</tt> operation, and the saved value is returned. If the | ||
| 214 | * iteration terminates without finding such an entry, <tt>null</tt> is | ||
| 215 | * returned. Note that this implementation requires linear time in the | ||
| 216 | * size of the map; many implementations will override this method. | ||
| 217 | * | ||
| 218 | * <p>Note that this implementation throws an | ||
| 219 | * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> | ||
| 220 | * iterator does not support the <tt>remove</tt> method and this map | ||
| 221 | * contains a mapping for the specified key. | ||
| 222 | * | ||
| 223 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 224 | * @throws ClassCastException {@inheritDoc} | ||
| 225 | * @throws NullPointerException {@inheritDoc} | ||
| 226 | */ | ||
| 227 | public V remove(Object key) { | ||
| 228 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 229 | Entry<K,V> correctEntry = null; | ||
| 230 | if (key==null) { | ||
| 231 | while (correctEntry==null && i.hasNext()) { | ||
| 232 | Entry<K,V> e = i.next(); | ||
| 233 | if (e.getKey()==null) | ||
| 234 | correctEntry = e; | ||
| 235 | } | ||
| 236 | } else { | ||
| 237 | while (correctEntry==null && i.hasNext()) { | ||
| 238 | Entry<K,V> e = i.next(); | ||
| 239 | if (key.equals(e.getKey())) | ||
| 240 | correctEntry = e; | ||
| 241 | } | ||
| 242 | } | ||
| 243 | |||
| 244 | V oldValue = null; | ||
| 245 | if (correctEntry !=null) { | ||
| 246 | oldValue = correctEntry.getValue(); | ||
| 247 | i.remove(); | ||
| 248 | } | ||
| 249 | return oldValue; | ||
| 250 | } | ||
| 251 | |||
| 252 | |||
| 253 | // Bulk Operations | ||
| 254 | |||
| 255 | /** | ||
| 256 | * {@inheritDoc} | ||
| 257 | * | ||
| 258 | * <p>This implementation iterates over the specified map's | ||
| 259 | * <tt>entrySet()</tt> collection, and calls this map's <tt>put</tt> | ||
| 260 | * operation once for each entry returned by the iteration. | ||
| 261 | * | ||
| 262 | * <p>Note that this implementation throws an | ||
| 263 | * <tt>UnsupportedOperationException</tt> if this map does not support | ||
| 264 | * the <tt>put</tt> operation and the specified map is nonempty. | ||
| 265 | * | ||
| 266 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 267 | * @throws ClassCastException {@inheritDoc} | ||
| 268 | * @throws NullPointerException {@inheritDoc} | ||
| 269 | * @throws IllegalArgumentException {@inheritDoc} | ||
| 270 | */ | ||
| 271 | public void putAll(Map<? extends K, ? extends V> m) { | ||
| 272 | for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) | ||
| 273 | put(e.getKey(), e.getValue()); | ||
| 274 | } | ||
| 275 | |||
| 276 | /** | ||
| 277 | * {@inheritDoc} | ||
| 278 | * | ||
| 279 | * <p>This implementation calls <tt>entrySet().clear()</tt>. | ||
| 280 | * | ||
| 281 | * <p>Note that this implementation throws an | ||
| 282 | * <tt>UnsupportedOperationException</tt> if the <tt>entrySet</tt> | ||
| 283 | * does not support the <tt>clear</tt> operation. | ||
| 284 | * | ||
| 285 | * @throws UnsupportedOperationException {@inheritDoc} | ||
| 286 | */ | ||
| 287 | public void clear() { | ||
| 288 | entrySet().clear(); | ||
| 289 | } | ||
| 290 | |||
| 291 | |||
| 292 | // Views | ||
| 293 | |||
| 294 | /** | ||
| 295 | * Each of these fields are initialized to contain an instance of the | ||
| 296 | * appropriate view the first time this view is requested. The views are | ||
| 297 | * stateless, so there's no reason to create more than one of each. | ||
| 298 | */ | ||
| 299 | transient volatile Set<K> keySet = null; | ||
| 300 | transient volatile Collection<V> values = null; | ||
| 301 | |||
| 302 | /** | ||
| 303 | * {@inheritDoc} | ||
| 304 | * | ||
| 305 | * <p>This implementation returns a set that subclasses {@link AbstractSet}. | ||
| 306 | * The subclass's iterator method returns a "wrapper object" over this | ||
| 307 | * map's <tt>entrySet()</tt> iterator. The <tt>size</tt> method | ||
| 308 | * delegates to this map's <tt>size</tt> method and the | ||
| 309 | * <tt>contains</tt> method delegates to this map's | ||
| 310 | * <tt>containsKey</tt> method. | ||
| 311 | * | ||
| 312 | * <p>The set is created the first time this method is called, | ||
| 313 | * and returned in response to all subsequent calls. No synchronization | ||
| 314 | * is performed, so there is a slight chance that multiple calls to this | ||
| 315 | * method will not all return the same set. | ||
| 316 | */ | ||
| 317 | public Set<K> keySet() { | ||
| 318 | if (keySet == null) { | ||
| 319 | keySet = new AbstractSet<K>() { | ||
| 320 | public Iterator<K> iterator() { | ||
| 321 | return new Iterator<K>() { | ||
| 322 | private Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 323 | |||
| 324 | public boolean hasNext() { | ||
| 325 | return i.hasNext(); | ||
| 326 | } | ||
| 327 | |||
| 328 | public K next() { | ||
| 329 | return i.next().getKey(); | ||
| 330 | } | ||
| 331 | |||
| 332 | public void remove() { | ||
| 333 | i.remove(); | ||
| 334 | } | ||
| 335 | }; | ||
| 336 | } | ||
| 337 | |||
| 338 | public int size() { | ||
| 339 | return AbstractMap.this.size(); | ||
| 340 | } | ||
| 341 | |||
| 342 | public boolean isEmpty() { | ||
| 343 | return AbstractMap.this.isEmpty(); | ||
| 344 | } | ||
| 345 | |||
| 346 | public void clear() { | ||
| 347 | AbstractMap.this.clear(); | ||
| 348 | } | ||
| 349 | |||
| 350 | public boolean contains(Object k) { | ||
| 351 | return AbstractMap.this.containsKey(k); | ||
| 352 | } | ||
| 353 | }; | ||
| 354 | } | ||
| 355 | return keySet; | ||
| 356 | } | ||
| 357 | |||
| 358 | /** | ||
| 359 | * {@inheritDoc} | ||
| 360 | * | ||
| 361 | * <p>This implementation returns a collection that subclasses {@link | ||
| 362 | * AbstractCollection}. The subclass's iterator method returns a | ||
| 363 | * "wrapper object" over this map's <tt>entrySet()</tt> iterator. | ||
| 364 | * The <tt>size</tt> method delegates to this map's <tt>size</tt> | ||
| 365 | * method and the <tt>contains</tt> method delegates to this map's | ||
| 366 | * <tt>containsValue</tt> method. | ||
| 367 | * | ||
| 368 | * <p>The collection is created the first time this method is called, and | ||
| 369 | * returned in response to all subsequent calls. No synchronization is | ||
| 370 | * performed, so there is a slight chance that multiple calls to this | ||
| 371 | * method will not all return the same collection. | ||
| 372 | */ | ||
| 373 | public Collection<V> values() { | ||
| 374 | if (values == null) { | ||
| 375 | values = new AbstractCollection<V>() { | ||
| 376 | public Iterator<V> iterator() { | ||
| 377 | return new Iterator<V>() { | ||
| 378 | private Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 379 | |||
| 380 | public boolean hasNext() { | ||
| 381 | return i.hasNext(); | ||
| 382 | } | ||
| 383 | |||
| 384 | public V next() { | ||
| 385 | return i.next().getValue(); | ||
| 386 | } | ||
| 387 | |||
| 388 | public void remove() { | ||
| 389 | i.remove(); | ||
| 390 | } | ||
| 391 | }; | ||
| 392 | } | ||
| 393 | |||
| 394 | public int size() { | ||
| 395 | return AbstractMap.this.size(); | ||
| 396 | } | ||
| 397 | |||
| 398 | public boolean isEmpty() { | ||
| 399 | return AbstractMap.this.isEmpty(); | ||
| 400 | } | ||
| 401 | |||
| 402 | public void clear() { | ||
| 403 | AbstractMap.this.clear(); | ||
| 404 | } | ||
| 405 | |||
| 406 | public boolean contains(Object v) { | ||
| 407 | return AbstractMap.this.containsValue(v); | ||
| 408 | } | ||
| 409 | }; | ||
| 410 | } | ||
| 411 | return values; | ||
| 412 | } | ||
| 413 | |||
| 414 | public abstract Set<Entry<K,V>> entrySet(); | ||
| 415 | |||
| 416 | |||
| 417 | // Comparison and hashing | ||
| 418 | |||
| 419 | /** | ||
| 420 | * Compares the specified object with this map for equality. Returns | ||
| 421 | * <tt>true</tt> if the given object is also a map and the two maps | ||
| 422 | * represent the same mappings. More formally, two maps <tt>m1</tt> and | ||
| 423 | * <tt>m2</tt> represent the same mappings if | ||
| 424 | * <tt>m1.entrySet().equals(m2.entrySet())</tt>. This ensures that the | ||
| 425 | * <tt>equals</tt> method works properly across different implementations | ||
| 426 | * of the <tt>Map</tt> interface. | ||
| 427 | * | ||
| 428 | * <p>This implementation first checks if the specified object is this map; | ||
| 429 | * if so it returns <tt>true</tt>. Then, it checks if the specified | ||
| 430 | * object is a map whose size is identical to the size of this map; if | ||
| 431 | * not, it returns <tt>false</tt>. If so, it iterates over this map's | ||
| 432 | * <tt>entrySet</tt> collection, and checks that the specified map | ||
| 433 | * contains each mapping that this map contains. If the specified map | ||
| 434 | * fails to contain such a mapping, <tt>false</tt> is returned. If the | ||
| 435 | * iteration completes, <tt>true</tt> is returned. | ||
| 436 | * | ||
| 437 | * @param o object to be compared for equality with this map | ||
| 438 | * @return <tt>true</tt> if the specified object is equal to this map | ||
| 439 | */ | ||
| 440 | public boolean equals(Object o) { | ||
| 441 | if (o == this) | ||
| 442 | return true; | ||
| 443 | |||
| 444 | if (!(o instanceof Map)) | ||
| 445 | return false; | ||
| 446 | Map<K,V> m = (Map<K,V>) o; | ||
| 447 | if (m.size() != size()) | ||
| 448 | return false; | ||
| 449 | |||
| 450 | try { | ||
| 451 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 452 | while (i.hasNext()) { | ||
| 453 | Entry<K,V> e = i.next(); | ||
| 454 | K key = e.getKey(); | ||
| 455 | V value = e.getValue(); | ||
| 456 | if (value == null) { | ||
| 457 | if (!(m.get(key)==null && m.containsKey(key))) | ||
| 458 | return false; | ||
| 459 | } else { | ||
| 460 | if (!value.equals(m.get(key))) | ||
| 461 | return false; | ||
| 462 | } | ||
| 463 | } | ||
| 464 | } catch (ClassCastException unused) { | ||
| 465 | return false; | ||
| 466 | } catch (NullPointerException unused) { | ||
| 467 | return false; | ||
| 468 | } | ||
| 469 | |||
| 470 | return true; | ||
| 471 | } | ||
| 472 | |||
| 473 | /** | ||
| 474 | * Returns the hash code value for this map. The hash code of a map is | ||
| 475 | * defined to be the sum of the hash codes of each entry in the map's | ||
| 476 | * <tt>entrySet()</tt> view. This ensures that <tt>m1.equals(m2)</tt> | ||
| 477 | * implies that <tt>m1.hashCode()==m2.hashCode()</tt> for any two maps | ||
| 478 | * <tt>m1</tt> and <tt>m2</tt>, as required by the general contract of | ||
| 479 | * {@link Object#hashCode}. | ||
| 480 | * | ||
| 481 | * <p>This implementation iterates over <tt>entrySet()</tt>, calling | ||
| 482 | * {@link Map.Entry#hashCode hashCode()} on each element (entry) in the | ||
| 483 | * set, and adding up the results. | ||
| 484 | * | ||
| 485 | * @return the hash code value for this map | ||
| 486 | * @see Map.Entry#hashCode() | ||
| 487 | * @see Object#equals(Object) | ||
| 488 | * @see Set#equals(Object) | ||
| 489 | */ | ||
| 490 | public int hashCode() { | ||
| 491 | int h = 0; | ||
| 492 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 493 | while (i.hasNext()) | ||
| 494 | h += i.next().hashCode(); | ||
| 495 | return h; | ||
| 496 | } | ||
| 497 | |||
| 498 | /** | ||
| 499 | * Returns a string representation of this map. The string representation | ||
| 500 | * consists of a list of key-value mappings in the order returned by the | ||
| 501 | * map's <tt>entrySet</tt> view's iterator, enclosed in braces | ||
| 502 | * (<tt>"{}"</tt>). Adjacent mappings are separated by the characters | ||
| 503 | * <tt>", "</tt> (comma and space). Each key-value mapping is rendered as | ||
| 504 | * the key followed by an equals sign (<tt>"="</tt>) followed by the | ||
| 505 | * associated value. Keys and values are converted to strings as by | ||
| 506 | * {@link String#valueOf(Object)}. | ||
| 507 | * | ||
| 508 | * @return a string representation of this map | ||
| 509 | */ | ||
| 510 | public String toString() { | ||
| 511 | Iterator<Entry<K,V>> i = entrySet().iterator(); | ||
| 512 | if (! i.hasNext()) | ||
| 513 | return "{}"; | ||
| 514 | |||
| 515 | StringBuilder sb = new StringBuilder(); | ||
| 516 | sb.append('{'); | ||
| 517 | for (;;) { | ||
| 518 | Entry<K,V> e = i.next(); | ||
| 519 | K key = e.getKey(); | ||
| 520 | V value = e.getValue(); | ||
| 521 | sb.append(key == this ? "(this Map)" : key); | ||
| 522 | sb.append('='); | ||
| 523 | sb.append(value == this ? "(this Map)" : value); | ||
| 524 | if (! i.hasNext()) | ||
| 525 | return sb.append('}').toString(); | ||
| 526 | sb.append(',').append(' '); | ||
| 527 | } | ||
| 528 | } | ||
| 529 | |||
| 530 | /** | ||
| 531 | * Returns a shallow copy of this <tt>AbstractMap</tt> instance: the keys | ||
| 532 | * and values themselves are not cloned. | ||
| 533 | * | ||
| 534 | * @return a shallow copy of this map | ||
| 535 | */ | ||
| 536 | protected Object clone() throws CloneNotSupportedException { | ||
| 537 | AbstractMap<K,V> result = (AbstractMap<K,V>)super.clone(); | ||
| 538 | result.keySet = null; | ||
| 539 | result.values = null; | ||
| 540 | return result; | ||
| 541 | } | ||
| 542 | |||
| 543 | /** | ||
| 544 | * Utility method for SimpleEntry and SimpleImmutableEntry. | ||
| 545 | * Test for equality, checking for nulls. | ||
| 546 | */ | ||
| 547 | private static boolean eq(Object o1, Object o2) { | ||
| 548 | return o1 == null ? o2 == null : o1.equals(o2); | ||
| 549 | } | ||
| 550 | |||
| 551 | // Implementation Note: SimpleEntry and SimpleImmutableEntry | ||
| 552 | // are distinct unrelated classes, even though they share | ||
| 553 | // some code. Since you can't add or subtract final-ness | ||
| 554 | // of a field in a subclass, they can't share representations, | ||
| 555 | // and the amount of duplicated code is too small to warrant | ||
| 556 | // exposing a common abstract class. | ||
| 557 | |||
| 558 | |||
| 559 | /** | ||
| 560 | * An Entry maintaining a key and a value. The value may be | ||
| 561 | * changed using the <tt>setValue</tt> method. This class | ||
| 562 | * facilitates the process of building custom map | ||
| 563 | * implementations. For example, it may be convenient to return | ||
| 564 | * arrays of <tt>SimpleEntry</tt> instances in method | ||
| 565 | * <tt>Map.entrySet().toArray</tt>. | ||
| 566 | * | ||
| 567 | * @since 1.6 | ||
| 568 | */ | ||
| 569 | public static class SimpleEntry<K,V> | ||
| 570 | implements Entry<K,V>, java.io.Serializable | ||
| 571 | { | ||
| 572 | private static final long serialVersionUID = -8499721149061103585L; | ||
| 573 | |||
| 574 | private final K key; | ||
| 575 | private V value; | ||
| 576 | |||
| 577 | /** | ||
| 578 | * Creates an entry representing a mapping from the specified | ||
| 579 | * key to the specified value. | ||
| 580 | * | ||
| 581 | * @param key the key represented by this entry | ||
| 582 | * @param value the value represented by this entry | ||
| 583 | */ | ||
| 584 | public SimpleEntry(K key, V value) { | ||
| 585 | this.key = key; | ||
| 586 | this.value = value; | ||
| 587 | } | ||
| 588 | |||
| 589 | /** | ||
| 590 | * Creates an entry representing the same mapping as the | ||
| 591 | * specified entry. | ||
| 592 | * | ||
| 593 | * @param entry the entry to copy | ||
| 594 | */ | ||
| 595 | public SimpleEntry(Entry<? extends K, ? extends V> entry) { | ||
| 596 | this.key = entry.getKey(); | ||
| 597 | this.value = entry.getValue(); | ||
| 598 | } | ||
| 599 | |||
| 600 | /** | ||
| 601 | * Returns the key corresponding to this entry. | ||
| 602 | * | ||
| 603 | * @return the key corresponding to this entry | ||
| 604 | */ | ||
| 605 | public K getKey() { | ||
| 606 | return key; | ||
| 607 | } | ||
| 608 | |||
| 609 | /** | ||
| 610 | * Returns the value corresponding to this entry. | ||
| 611 | * | ||
| 612 | * @return the value corresponding to this entry | ||
| 613 | */ | ||
| 614 | public V getValue() { | ||
| 615 | return value; | ||
| 616 | } | ||
| 617 | |||
| 618 | /** | ||
| 619 | * Replaces the value corresponding to this entry with the specified | ||
| 620 | * value. | ||
| 621 | * | ||
| 622 | * @param value new value to be stored in this entry | ||
| 623 | * @return the old value corresponding to the entry | ||
| 624 | */ | ||
| 625 | public V setValue(V value) { | ||
| 626 | V oldValue = this.value; | ||
| 627 | this.value = value; | ||
| 628 | return oldValue; | ||
| 629 | } | ||
| 630 | |||
| 631 | /** | ||
| 632 | * Compares the specified object with this entry for equality. | ||
| 633 | * Returns {@code true} if the given object is also a map entry and | ||
| 634 | * the two entries represent the same mapping. More formally, two | ||
| 635 | * entries {@code e1} and {@code e2} represent the same mapping | ||
| 636 | * if<pre> | ||
| 637 | * (e1.getKey()==null ? | ||
| 638 | * e2.getKey()==null : | ||
| 639 | * e1.getKey().equals(e2.getKey())) | ||
| 640 | * && | ||
| 641 | * (e1.getValue()==null ? | ||
| 642 | * e2.getValue()==null : | ||
| 643 | * e1.getValue().equals(e2.getValue()))</pre> | ||
| 644 | * This ensures that the {@code equals} method works properly across | ||
| 645 | * different implementations of the {@code Map.Entry} interface. | ||
| 646 | * | ||
| 647 | * @param o object to be compared for equality with this map entry | ||
| 648 | * @return {@code true} if the specified object is equal to this map | ||
| 649 | * entry | ||
| 650 | * @see #hashCode | ||
| 651 | */ | ||
| 652 | public boolean equals(Object o) { | ||
| 653 | if (!(o instanceof Map.Entry)) | ||
| 654 | return false; | ||
| 655 | Map.Entry e = (Map.Entry)o; | ||
| 656 | return eq(key, e.getKey()) && eq(value, e.getValue()); | ||
| 657 | } | ||
| 658 | |||
| 659 | /** | ||
| 660 | * Returns the hash code value for this map entry. The hash code | ||
| 661 | * of a map entry {@code e} is defined to be: <pre> | ||
| 662 | * (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ | ||
| 663 | * (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> | ||
| 664 | * This ensures that {@code e1.equals(e2)} implies that | ||
| 665 | * {@code e1.hashCode()==e2.hashCode()} for any two Entries | ||
| 666 | * {@code e1} and {@code e2}, as required by the general | ||
| 667 | * contract of {@link Object#hashCode}. | ||
| 668 | * | ||
| 669 | * @return the hash code value for this map entry | ||
| 670 | * @see #equals | ||
| 671 | */ | ||
| 672 | public int hashCode() { | ||
| 673 | return (key == null ? 0 : key.hashCode()) ^ | ||
| 674 | (value == null ? 0 : value.hashCode()); | ||
| 675 | } | ||
| 676 | |||
| 677 | /** | ||
| 678 | * Returns a String representation of this map entry. This | ||
| 679 | * implementation returns the string representation of this | ||
| 680 | * entry's key followed by the equals character ("<tt>=</tt>") | ||
| 681 | * followed by the string representation of this entry's value. | ||
| 682 | * | ||
| 683 | * @return a String representation of this map entry | ||
| 684 | */ | ||
| 685 | public String toString() { | ||
| 686 | return key + "=" + value; | ||
| 687 | } | ||
| 688 | |||
| 689 | } | ||
| 690 | |||
| 691 | /** | ||
| 692 | * An Entry maintaining an immutable key and value. This class | ||
| 693 | * does not support method <tt>setValue</tt>. This class may be | ||
| 694 | * convenient in methods that return thread-safe snapshots of | ||
| 695 | * key-value mappings. | ||
| 696 | * | ||
| 697 | * @since 1.6 | ||
| 698 | */ | ||
| 699 | public static class SimpleImmutableEntry<K,V> | ||
| 700 | implements Entry<K,V>, java.io.Serializable | ||
| 701 | { | ||
| 702 | private static final long serialVersionUID = 7138329143949025153L; | ||
| 703 | |||
| 704 | private final K key; | ||
| 705 | private final V value; | ||
| 706 | |||
| 707 | /** | ||
| 708 | * Creates an entry representing a mapping from the specified | ||
| 709 | * key to the specified value. | ||
| 710 | * | ||
| 711 | * @param key the key represented by this entry | ||
| 712 | * @param value the value represented by this entry | ||
| 713 | */ | ||
| 714 | public SimpleImmutableEntry(K key, V value) { | ||
| 715 | this.key = key; | ||
| 716 | this.value = value; | ||
| 717 | } | ||
| 718 | |||
| 719 | /** | ||
| 720 | * Creates an entry representing the same mapping as the | ||
| 721 | * specified entry. | ||
| 722 | * | ||
| 723 | * @param entry the entry to copy | ||
| 724 | */ | ||
| 725 | public SimpleImmutableEntry(Entry<? extends K, ? extends V> entry) { | ||
| 726 | this.key = entry.getKey(); | ||
| 727 | this.value = entry.getValue(); | ||
| 728 | } | ||
| 729 | |||
| 730 | /** | ||
| 731 | * Returns the key corresponding to this entry. | ||
| 732 | * | ||
| 733 | * @return the key corresponding to this entry | ||
| 734 | */ | ||
| 735 | public K getKey() { | ||
| 736 | return key; | ||
| 737 | } | ||
| 738 | |||
| 739 | /** | ||
| 740 | * Returns the value corresponding to this entry. | ||
| 741 | * | ||
| 742 | * @return the value corresponding to this entry | ||
| 743 | */ | ||
| 744 | public V getValue() { | ||
| 745 | return value; | ||
| 746 | } | ||
| 747 | |||
| 748 | /** | ||
| 749 | * Replaces the value corresponding to this entry with the specified | ||
| 750 | * value (optional operation). This implementation simply throws | ||
| 751 | * <tt>UnsupportedOperationException</tt>, as this class implements | ||
| 752 | * an <i>immutable</i> map entry. | ||
| 753 | * | ||
| 754 | * @param value new value to be stored in this entry | ||
| 755 | * @return (Does not return) | ||
| 756 | * @throws UnsupportedOperationException always | ||
| 757 | */ | ||
| 758 | public V setValue(V value) { | ||
| 759 | throw new UnsupportedOperationException(); | ||
| 760 | } | ||
| 761 | |||
| 762 | /** | ||
| 763 | * Compares the specified object with this entry for equality. | ||
| 764 | * Returns {@code true} if the given object is also a map entry and | ||
| 765 | * the two entries represent the same mapping. More formally, two | ||
| 766 | * entries {@code e1} and {@code e2} represent the same mapping | ||
| 767 | * if<pre> | ||
| 768 | * (e1.getKey()==null ? | ||
| 769 | * e2.getKey()==null : | ||
| 770 | * e1.getKey().equals(e2.getKey())) | ||
| 771 | * && | ||
| 772 | * (e1.getValue()==null ? | ||
| 773 | * e2.getValue()==null : | ||
| 774 | * e1.getValue().equals(e2.getValue()))</pre> | ||
| 775 | * This ensures that the {@code equals} method works properly across | ||
| 776 | * different implementations of the {@code Map.Entry} interface. | ||
| 777 | * | ||
| 778 | * @param o object to be compared for equality with this map entry | ||
| 779 | * @return {@code true} if the specified object is equal to this map | ||
| 780 | * entry | ||
| 781 | * @see #hashCode | ||
| 782 | */ | ||
| 783 | public boolean equals(Object o) { | ||
| 784 | if (!(o instanceof Map.Entry)) | ||
| 785 | return false; | ||
| 786 | Map.Entry e = (Map.Entry)o; | ||
| 787 | return eq(key, e.getKey()) && eq(value, e.getValue()); | ||
| 788 | } | ||
| 789 | |||
| 790 | /** | ||
| 791 | * Returns the hash code value for this map entry. The hash code | ||
| 792 | * of a map entry {@code e} is defined to be: <pre> | ||
| 793 | * (e.getKey()==null ? 0 : e.getKey().hashCode()) ^ | ||
| 794 | * (e.getValue()==null ? 0 : e.getValue().hashCode())</pre> | ||
| 795 | * This ensures that {@code e1.equals(e2)} implies that | ||
| 796 | * {@code e1.hashCode()==e2.hashCode()} for any two Entries | ||
| 797 | * {@code e1} and {@code e2}, as required by the general | ||
| 798 | * contract of {@link Object#hashCode}. | ||
| 799 | * | ||
| 800 | * @return the hash code value for this map entry | ||
| 801 | * @see #equals | ||
| 802 | */ | ||
| 803 | public int hashCode() { | ||
| 804 | return (key == null ? 0 : key.hashCode()) ^ | ||
| 805 | (value == null ? 0 : value.hashCode()); | ||
| 806 | } | ||
| 807 | |||
| 808 | /** | ||
| 809 | * Returns a String representation of this map entry. This | ||
| 810 | * implementation returns the string representation of this | ||
| 811 | * entry's key followed by the equals character ("<tt>=</tt>") | ||
| 812 | * followed by the string representation of this entry's value. | ||
| 813 | * | ||
| 814 | * @return a String representation of this map entry | ||
| 815 | */ | ||
| 816 | public String toString() { | ||
| 817 | return key + "=" + value; | ||
| 818 | } | ||
| 819 | |||
| 820 | } | ||
| 821 | |||
| 822 | } | ||