J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1997-2007 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.util; |
| 27 | |
| 28 | /** |
| 29 | * This class provides a skeletal implementation of the {@link List} |
| 30 | * interface to minimize the effort required to implement this interface |
| 31 | * backed by a "random access" data store (such as an array). For sequential |
| 32 | * access data (such as a linked list), {@link AbstractSequentialList} should |
| 33 | * be used in preference to this class. |
| 34 | * |
| 35 | * <p>To implement an unmodifiable list, the programmer needs only to extend |
| 36 | * this class and provide implementations for the {@link #get(int)} and |
| 37 | * {@link List#size() size()} methods. |
| 38 | * |
| 39 | * <p>To implement a modifiable list, the programmer must additionally |
| 40 | * override the {@link #set(int, Object) set(int, E)} method (which otherwise |
| 41 | * throws an {@code UnsupportedOperationException}). If the list is |
| 42 | * variable-size the programmer must additionally override the |
| 43 | * {@link #add(int, Object) add(int, E)} and {@link #remove(int)} methods. |
| 44 | * |
| 45 | * <p>The programmer should generally provide a void (no argument) and collection |
| 46 | * constructor, as per the recommendation in the {@link Collection} interface |
| 47 | * specification. |
| 48 | * |
| 49 | * <p>Unlike the other abstract collection implementations, the programmer does |
| 50 | * <i>not</i> have to provide an iterator implementation; the iterator and |
| 51 | * list iterator are implemented by this class, on top of the "random access" |
| 52 | * methods: |
| 53 | * {@link #get(int)}, |
| 54 | * {@link #set(int, Object) set(int, E)}, |
| 55 | * {@link #add(int, Object) add(int, E)} and |
| 56 | * {@link #remove(int)}. |
| 57 | * |
| 58 | * <p>The documentation for each non-abstract method in this class describes its |
| 59 | * implementation in detail. Each of these methods may be overridden if the |
| 60 | * collection being implemented admits a more efficient implementation. |
| 61 | * |
| 62 | * <p>This class is a member of the |
| 63 | * <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
| 64 | * Java Collections Framework</a>. |
| 65 | * |
| 66 | * @author Josh Bloch |
| 67 | * @author Neal Gafter |
| 68 | * @since 1.2 |
| 69 | */ |
| 70 | |
| 71 | public abstract class AbstractList<E> extends AbstractCollection<E> implements List<E> { |
| 72 | /** |
| 73 | * Sole constructor. (For invocation by subclass constructors, typically |
| 74 | * implicit.) |
| 75 | */ |
| 76 | protected AbstractList() { |
| 77 | } |
| 78 | |
| 79 | /** |
| 80 | * Appends the specified element to the end of this list (optional |
| 81 | * operation). |
| 82 | * |
| 83 | * <p>Lists that support this operation may place limitations on what |
| 84 | * elements may be added to this list. In particular, some |
| 85 | * lists will refuse to add null elements, and others will impose |
| 86 | * restrictions on the type of elements that may be added. List |
| 87 | * classes should clearly specify in their documentation any restrictions |
| 88 | * on what elements may be added. |
| 89 | * |
| 90 | * <p>This implementation calls {@code add(size(), e)}. |
| 91 | * |
| 92 | * <p>Note that this implementation throws an |
| 93 | * {@code UnsupportedOperationException} unless |
| 94 | * {@link #add(int, Object) add(int, E)} is overridden. |
| 95 | * |
| 96 | * @param e element to be appended to this list |
| 97 | * @return {@code true} (as specified by {@link Collection#add}) |
| 98 | * @throws UnsupportedOperationException if the {@code add} operation |
| 99 | * is not supported by this list |
| 100 | * @throws ClassCastException if the class of the specified element |
| 101 | * prevents it from being added to this list |
| 102 | * @throws NullPointerException if the specified element is null and this |
| 103 | * list does not permit null elements |
| 104 | * @throws IllegalArgumentException if some property of this element |
| 105 | * prevents it from being added to this list |
| 106 | */ |
| 107 | public boolean add(E e) { |
| 108 | add(size(), e); |
| 109 | return true; |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * {@inheritDoc} |
| 114 | * |
| 115 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 116 | */ |
| 117 | abstract public E get(int index); |
| 118 | |
| 119 | /** |
| 120 | * {@inheritDoc} |
| 121 | * |
| 122 | * <p>This implementation always throws an |
| 123 | * {@code UnsupportedOperationException}. |
| 124 | * |
| 125 | * @throws UnsupportedOperationException {@inheritDoc} |
| 126 | * @throws ClassCastException {@inheritDoc} |
| 127 | * @throws NullPointerException {@inheritDoc} |
| 128 | * @throws IllegalArgumentException {@inheritDoc} |
| 129 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 130 | */ |
| 131 | public E set(int index, E element) { |
| 132 | throw new UnsupportedOperationException(); |
| 133 | } |
| 134 | |
| 135 | /** |
| 136 | * {@inheritDoc} |
| 137 | * |
| 138 | * <p>This implementation always throws an |
| 139 | * {@code UnsupportedOperationException}. |
| 140 | * |
| 141 | * @throws UnsupportedOperationException {@inheritDoc} |
| 142 | * @throws ClassCastException {@inheritDoc} |
| 143 | * @throws NullPointerException {@inheritDoc} |
| 144 | * @throws IllegalArgumentException {@inheritDoc} |
| 145 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 146 | */ |
| 147 | public void add(int index, E element) { |
| 148 | throw new UnsupportedOperationException(); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * {@inheritDoc} |
| 153 | * |
| 154 | * <p>This implementation always throws an |
| 155 | * {@code UnsupportedOperationException}. |
| 156 | * |
| 157 | * @throws UnsupportedOperationException {@inheritDoc} |
| 158 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 159 | */ |
| 160 | public E remove(int index) { |
| 161 | throw new UnsupportedOperationException(); |
| 162 | } |
| 163 | |
| 164 | |
| 165 | // Search Operations |
| 166 | |
| 167 | /** |
| 168 | * {@inheritDoc} |
| 169 | * |
| 170 | * <p>This implementation first gets a list iterator (with |
| 171 | * {@code listIterator()}). Then, it iterates over the list until the |
| 172 | * specified element is found or the end of the list is reached. |
| 173 | * |
| 174 | * @throws ClassCastException {@inheritDoc} |
| 175 | * @throws NullPointerException {@inheritDoc} |
| 176 | */ |
| 177 | public int indexOf(Object o) { |
| 178 | ListIterator<E> e = listIterator(); |
| 179 | if (o==null) { |
| 180 | while (e.hasNext()) |
| 181 | if (e.next()==null) |
| 182 | return e.previousIndex(); |
| 183 | } else { |
| 184 | while (e.hasNext()) |
| 185 | if (o.equals(e.next())) |
| 186 | return e.previousIndex(); |
| 187 | } |
| 188 | return -1; |
| 189 | } |
| 190 | |
| 191 | /** |
| 192 | * {@inheritDoc} |
| 193 | * |
| 194 | * <p>This implementation first gets a list iterator that points to the end |
| 195 | * of the list (with {@code listIterator(size())}). Then, it iterates |
| 196 | * backwards over the list until the specified element is found, or the |
| 197 | * beginning of the list is reached. |
| 198 | * |
| 199 | * @throws ClassCastException {@inheritDoc} |
| 200 | * @throws NullPointerException {@inheritDoc} |
| 201 | */ |
| 202 | public int lastIndexOf(Object o) { |
| 203 | ListIterator<E> e = listIterator(size()); |
| 204 | if (o==null) { |
| 205 | while (e.hasPrevious()) |
| 206 | if (e.previous()==null) |
| 207 | return e.nextIndex(); |
| 208 | } else { |
| 209 | while (e.hasPrevious()) |
| 210 | if (o.equals(e.previous())) |
| 211 | return e.nextIndex(); |
| 212 | } |
| 213 | return -1; |
| 214 | } |
| 215 | |
| 216 | |
| 217 | // Bulk Operations |
| 218 | |
| 219 | /** |
| 220 | * Removes all of the elements from this list (optional operation). |
| 221 | * The list will be empty after this call returns. |
| 222 | * |
| 223 | * <p>This implementation calls {@code removeRange(0, size())}. |
| 224 | * |
| 225 | * <p>Note that this implementation throws an |
| 226 | * {@code UnsupportedOperationException} unless {@code remove(int |
| 227 | * index)} or {@code removeRange(int fromIndex, int toIndex)} is |
| 228 | * overridden. |
| 229 | * |
| 230 | * @throws UnsupportedOperationException if the {@code clear} operation |
| 231 | * is not supported by this list |
| 232 | */ |
| 233 | public void clear() { |
| 234 | removeRange(0, size()); |
| 235 | } |
| 236 | |
| 237 | /** |
| 238 | * {@inheritDoc} |
| 239 | * |
| 240 | * <p>This implementation gets an iterator over the specified collection |
| 241 | * and iterates over it, inserting the elements obtained from the |
| 242 | * iterator into this list at the appropriate position, one at a time, |
| 243 | * using {@code add(int, E)}. |
| 244 | * Many implementations will override this method for efficiency. |
| 245 | * |
| 246 | * <p>Note that this implementation throws an |
| 247 | * {@code UnsupportedOperationException} unless |
| 248 | * {@link #add(int, Object) add(int, E)} is overridden. |
| 249 | * |
| 250 | * @throws UnsupportedOperationException {@inheritDoc} |
| 251 | * @throws ClassCastException {@inheritDoc} |
| 252 | * @throws NullPointerException {@inheritDoc} |
| 253 | * @throws IllegalArgumentException {@inheritDoc} |
| 254 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 255 | */ |
| 256 | public boolean addAll(int index, Collection<? extends E> c) { |
| 257 | rangeCheckForAdd(index); |
| 258 | boolean modified = false; |
| 259 | Iterator<? extends E> e = c.iterator(); |
| 260 | while (e.hasNext()) { |
| 261 | add(index++, e.next()); |
| 262 | modified = true; |
| 263 | } |
| 264 | return modified; |
| 265 | } |
| 266 | |
| 267 | |
| 268 | // Iterators |
| 269 | |
| 270 | /** |
| 271 | * Returns an iterator over the elements in this list in proper sequence. |
| 272 | * |
| 273 | * <p>This implementation returns a straightforward implementation of the |
| 274 | * iterator interface, relying on the backing list's {@code size()}, |
| 275 | * {@code get(int)}, and {@code remove(int)} methods. |
| 276 | * |
| 277 | * <p>Note that the iterator returned by this method will throw an |
| 278 | * {@link UnsupportedOperationException} in response to its |
| 279 | * {@code remove} method unless the list's {@code remove(int)} method is |
| 280 | * overridden. |
| 281 | * |
| 282 | * <p>This implementation can be made to throw runtime exceptions in the |
| 283 | * face of concurrent modification, as described in the specification |
| 284 | * for the (protected) {@link #modCount} field. |
| 285 | * |
| 286 | * @return an iterator over the elements in this list in proper sequence |
| 287 | */ |
| 288 | public Iterator<E> iterator() { |
| 289 | return new Itr(); |
| 290 | } |
| 291 | |
| 292 | /** |
| 293 | * {@inheritDoc} |
| 294 | * |
| 295 | * <p>This implementation returns {@code listIterator(0)}. |
| 296 | * |
| 297 | * @see #listIterator(int) |
| 298 | */ |
| 299 | public ListIterator<E> listIterator() { |
| 300 | return listIterator(0); |
| 301 | } |
| 302 | |
| 303 | /** |
| 304 | * {@inheritDoc} |
| 305 | * |
| 306 | * <p>This implementation returns a straightforward implementation of the |
| 307 | * {@code ListIterator} interface that extends the implementation of the |
| 308 | * {@code Iterator} interface returned by the {@code iterator()} method. |
| 309 | * The {@code ListIterator} implementation relies on the backing list's |
| 310 | * {@code get(int)}, {@code set(int, E)}, {@code add(int, E)} |
| 311 | * and {@code remove(int)} methods. |
| 312 | * |
| 313 | * <p>Note that the list iterator returned by this implementation will |
| 314 | * throw an {@link UnsupportedOperationException} in response to its |
| 315 | * {@code remove}, {@code set} and {@code add} methods unless the |
| 316 | * list's {@code remove(int)}, {@code set(int, E)}, and |
| 317 | * {@code add(int, E)} methods are overridden. |
| 318 | * |
| 319 | * <p>This implementation can be made to throw runtime exceptions in the |
| 320 | * face of concurrent modification, as described in the specification for |
| 321 | * the (protected) {@link #modCount} field. |
| 322 | * |
| 323 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 324 | */ |
| 325 | public ListIterator<E> listIterator(final int index) { |
| 326 | rangeCheckForAdd(index); |
| 327 | |
| 328 | return new ListItr(index); |
| 329 | } |
| 330 | |
| 331 | private class Itr implements Iterator<E> { |
| 332 | /** |
| 333 | * Index of element to be returned by subsequent call to next. |
| 334 | */ |
| 335 | int cursor = 0; |
| 336 | |
| 337 | /** |
| 338 | * Index of element returned by most recent call to next or |
| 339 | * previous. Reset to -1 if this element is deleted by a call |
| 340 | * to remove. |
| 341 | */ |
| 342 | int lastRet = -1; |
| 343 | |
| 344 | /** |
| 345 | * The modCount value that the iterator believes that the backing |
| 346 | * List should have. If this expectation is violated, the iterator |
| 347 | * has detected concurrent modification. |
| 348 | */ |
| 349 | int expectedModCount = modCount; |
| 350 | |
| 351 | public boolean hasNext() { |
| 352 | return cursor != size(); |
| 353 | } |
| 354 | |
| 355 | public E next() { |
| 356 | checkForComodification(); |
| 357 | try { |
| 358 | int i = cursor; |
| 359 | E next = get(i); |
| 360 | lastRet = i; |
| 361 | cursor = i + 1; |
| 362 | return next; |
| 363 | } catch (IndexOutOfBoundsException e) { |
| 364 | checkForComodification(); |
| 365 | throw new NoSuchElementException(); |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | public void remove() { |
| 370 | if (lastRet < 0) |
| 371 | throw new IllegalStateException(); |
| 372 | checkForComodification(); |
| 373 | |
| 374 | try { |
| 375 | AbstractList.this.remove(lastRet); |
| 376 | if (lastRet < cursor) |
| 377 | cursor--; |
| 378 | lastRet = -1; |
| 379 | expectedModCount = modCount; |
| 380 | } catch (IndexOutOfBoundsException e) { |
| 381 | throw new ConcurrentModificationException(); |
| 382 | } |
| 383 | } |
| 384 | |
| 385 | final void checkForComodification() { |
| 386 | if (modCount != expectedModCount) |
| 387 | throw new ConcurrentModificationException(); |
| 388 | } |
| 389 | } |
| 390 | |
| 391 | private class ListItr extends Itr implements ListIterator<E> { |
| 392 | ListItr(int index) { |
| 393 | cursor = index; |
| 394 | } |
| 395 | |
| 396 | public boolean hasPrevious() { |
| 397 | return cursor != 0; |
| 398 | } |
| 399 | |
| 400 | public E previous() { |
| 401 | checkForComodification(); |
| 402 | try { |
| 403 | int i = cursor - 1; |
| 404 | E previous = get(i); |
| 405 | lastRet = cursor = i; |
| 406 | return previous; |
| 407 | } catch (IndexOutOfBoundsException e) { |
| 408 | checkForComodification(); |
| 409 | throw new NoSuchElementException(); |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | public int nextIndex() { |
| 414 | return cursor; |
| 415 | } |
| 416 | |
| 417 | public int previousIndex() { |
| 418 | return cursor-1; |
| 419 | } |
| 420 | |
| 421 | public void set(E e) { |
| 422 | if (lastRet < 0) |
| 423 | throw new IllegalStateException(); |
| 424 | checkForComodification(); |
| 425 | |
| 426 | try { |
| 427 | AbstractList.this.set(lastRet, e); |
| 428 | expectedModCount = modCount; |
| 429 | } catch (IndexOutOfBoundsException ex) { |
| 430 | throw new ConcurrentModificationException(); |
| 431 | } |
| 432 | } |
| 433 | |
| 434 | public void add(E e) { |
| 435 | checkForComodification(); |
| 436 | |
| 437 | try { |
| 438 | int i = cursor; |
| 439 | AbstractList.this.add(i, e); |
| 440 | lastRet = -1; |
| 441 | cursor = i + 1; |
| 442 | expectedModCount = modCount; |
| 443 | } catch (IndexOutOfBoundsException ex) { |
| 444 | throw new ConcurrentModificationException(); |
| 445 | } |
| 446 | } |
| 447 | } |
| 448 | |
| 449 | /** |
| 450 | * {@inheritDoc} |
| 451 | * |
| 452 | * <p>This implementation returns a list that subclasses |
| 453 | * {@code AbstractList}. The subclass stores, in private fields, the |
| 454 | * offset of the subList within the backing list, the size of the subList |
| 455 | * (which can change over its lifetime), and the expected |
| 456 | * {@code modCount} value of the backing list. There are two variants |
| 457 | * of the subclass, one of which implements {@code RandomAccess}. |
| 458 | * If this list implements {@code RandomAccess} the returned list will |
| 459 | * be an instance of the subclass that implements {@code RandomAccess}. |
| 460 | * |
| 461 | * <p>The subclass's {@code set(int, E)}, {@code get(int)}, |
| 462 | * {@code add(int, E)}, {@code remove(int)}, {@code addAll(int, |
| 463 | * Collection)} and {@code removeRange(int, int)} methods all |
| 464 | * delegate to the corresponding methods on the backing abstract list, |
| 465 | * after bounds-checking the index and adjusting for the offset. The |
| 466 | * {@code addAll(Collection c)} method merely returns {@code addAll(size, |
| 467 | * c)}. |
| 468 | * |
| 469 | * <p>The {@code listIterator(int)} method returns a "wrapper object" |
| 470 | * over a list iterator on the backing list, which is created with the |
| 471 | * corresponding method on the backing list. The {@code iterator} method |
| 472 | * merely returns {@code listIterator()}, and the {@code size} method |
| 473 | * merely returns the subclass's {@code size} field. |
| 474 | * |
| 475 | * <p>All methods first check to see if the actual {@code modCount} of |
| 476 | * the backing list is equal to its expected value, and throw a |
| 477 | * {@code ConcurrentModificationException} if it is not. |
| 478 | * |
| 479 | * @throws IndexOutOfBoundsException if an endpoint index value is out of range |
| 480 | * {@code (fromIndex < 0 || toIndex > size)} |
| 481 | * @throws IllegalArgumentException if the endpoint indices are out of order |
| 482 | * {@code (fromIndex > toIndex)} |
| 483 | */ |
| 484 | public List<E> subList(int fromIndex, int toIndex) { |
| 485 | return (this instanceof RandomAccess ? |
| 486 | new RandomAccessSubList<E>(this, fromIndex, toIndex) : |
| 487 | new SubList<E>(this, fromIndex, toIndex)); |
| 488 | } |
| 489 | |
| 490 | // Comparison and hashing |
| 491 | |
| 492 | /** |
| 493 | * Compares the specified object with this list for equality. Returns |
| 494 | * {@code true} if and only if the specified object is also a list, both |
| 495 | * lists have the same size, and all corresponding pairs of elements in |
| 496 | * the two lists are <i>equal</i>. (Two elements {@code e1} and |
| 497 | * {@code e2} are <i>equal</i> if {@code (e1==null ? e2==null : |
| 498 | * e1.equals(e2))}.) In other words, two lists are defined to be |
| 499 | * equal if they contain the same elements in the same order.<p> |
| 500 | * |
| 501 | * This implementation first checks if the specified object is this |
| 502 | * list. If so, it returns {@code true}; if not, it checks if the |
| 503 | * specified object is a list. If not, it returns {@code false}; if so, |
| 504 | * it iterates over both lists, comparing corresponding pairs of elements. |
| 505 | * If any comparison returns {@code false}, this method returns |
| 506 | * {@code false}. If either iterator runs out of elements before the |
| 507 | * other it returns {@code false} (as the lists are of unequal length); |
| 508 | * otherwise it returns {@code true} when the iterations complete. |
| 509 | * |
| 510 | * @param o the object to be compared for equality with this list |
| 511 | * @return {@code true} if the specified object is equal to this list |
| 512 | */ |
| 513 | public boolean equals(Object o) { |
| 514 | if (o == this) |
| 515 | return true; |
| 516 | if (!(o instanceof List)) |
| 517 | return false; |
| 518 | |
| 519 | ListIterator<E> e1 = listIterator(); |
| 520 | ListIterator e2 = ((List) o).listIterator(); |
| 521 | while(e1.hasNext() && e2.hasNext()) { |
| 522 | E o1 = e1.next(); |
| 523 | Object o2 = e2.next(); |
| 524 | if (!(o1==null ? o2==null : o1.equals(o2))) |
| 525 | return false; |
| 526 | } |
| 527 | return !(e1.hasNext() || e2.hasNext()); |
| 528 | } |
| 529 | |
| 530 | /** |
| 531 | * Returns the hash code value for this list. |
| 532 | * |
| 533 | * <p>This implementation uses exactly the code that is used to define the |
| 534 | * list hash function in the documentation for the {@link List#hashCode} |
| 535 | * method. |
| 536 | * |
| 537 | * @return the hash code value for this list |
| 538 | */ |
| 539 | public int hashCode() { |
| 540 | int hashCode = 1; |
| 541 | for (E e : this) |
| 542 | hashCode = 31*hashCode + (e==null ? 0 : e.hashCode()); |
| 543 | return hashCode; |
| 544 | } |
| 545 | |
| 546 | /** |
| 547 | * Removes from this list all of the elements whose index is between |
| 548 | * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. |
| 549 | * Shifts any succeeding elements to the left (reduces their index). |
| 550 | * This call shortens the list by {@code (toIndex - fromIndex)} elements. |
| 551 | * (If {@code toIndex==fromIndex}, this operation has no effect.) |
| 552 | * |
| 553 | * <p>This method is called by the {@code clear} operation on this list |
| 554 | * and its subLists. Overriding this method to take advantage of |
| 555 | * the internals of the list implementation can <i>substantially</i> |
| 556 | * improve the performance of the {@code clear} operation on this list |
| 557 | * and its subLists. |
| 558 | * |
| 559 | * <p>This implementation gets a list iterator positioned before |
| 560 | * {@code fromIndex}, and repeatedly calls {@code ListIterator.next} |
| 561 | * followed by {@code ListIterator.remove} until the entire range has |
| 562 | * been removed. <b>Note: if {@code ListIterator.remove} requires linear |
| 563 | * time, this implementation requires quadratic time.</b> |
| 564 | * |
| 565 | * @param fromIndex index of first element to be removed |
| 566 | * @param toIndex index after last element to be removed |
| 567 | */ |
| 568 | protected void removeRange(int fromIndex, int toIndex) { |
| 569 | ListIterator<E> it = listIterator(fromIndex); |
| 570 | for (int i=0, n=toIndex-fromIndex; i<n; i++) { |
| 571 | it.next(); |
| 572 | it.remove(); |
| 573 | } |
| 574 | } |
| 575 | |
| 576 | /** |
| 577 | * The number of times this list has been <i>structurally modified</i>. |
| 578 | * Structural modifications are those that change the size of the |
| 579 | * list, or otherwise perturb it in such a fashion that iterations in |
| 580 | * progress may yield incorrect results. |
| 581 | * |
| 582 | * <p>This field is used by the iterator and list iterator implementation |
| 583 | * returned by the {@code iterator} and {@code listIterator} methods. |
| 584 | * If the value of this field changes unexpectedly, the iterator (or list |
| 585 | * iterator) will throw a {@code ConcurrentModificationException} in |
| 586 | * response to the {@code next}, {@code remove}, {@code previous}, |
| 587 | * {@code set} or {@code add} operations. This provides |
| 588 | * <i>fail-fast</i> behavior, rather than non-deterministic behavior in |
| 589 | * the face of concurrent modification during iteration. |
| 590 | * |
| 591 | * <p><b>Use of this field by subclasses is optional.</b> If a subclass |
| 592 | * wishes to provide fail-fast iterators (and list iterators), then it |
| 593 | * merely has to increment this field in its {@code add(int, E)} and |
| 594 | * {@code remove(int)} methods (and any other methods that it overrides |
| 595 | * that result in structural modifications to the list). A single call to |
| 596 | * {@code add(int, E)} or {@code remove(int)} must add no more than |
| 597 | * one to this field, or the iterators (and list iterators) will throw |
| 598 | * bogus {@code ConcurrentModificationExceptions}. If an implementation |
| 599 | * does not wish to provide fail-fast iterators, this field may be |
| 600 | * ignored. |
| 601 | */ |
| 602 | protected transient int modCount = 0; |
| 603 | |
| 604 | private void rangeCheckForAdd(int index) { |
| 605 | if (index < 0 || index > size()) |
| 606 | throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); |
| 607 | } |
| 608 | |
| 609 | private String outOfBoundsMsg(int index) { |
| 610 | return "Index: "+index+", Size: "+size(); |
| 611 | } |
| 612 | } |
| 613 | |
| 614 | class SubList<E> extends AbstractList<E> { |
| 615 | private final AbstractList<E> l; |
| 616 | private final int offset; |
| 617 | private int size; |
| 618 | |
| 619 | SubList(AbstractList<E> list, int fromIndex, int toIndex) { |
| 620 | if (fromIndex < 0) |
| 621 | throw new IndexOutOfBoundsException("fromIndex = " + fromIndex); |
| 622 | if (toIndex > list.size()) |
| 623 | throw new IndexOutOfBoundsException("toIndex = " + toIndex); |
| 624 | if (fromIndex > toIndex) |
| 625 | throw new IllegalArgumentException("fromIndex(" + fromIndex + |
| 626 | ") > toIndex(" + toIndex + ")"); |
| 627 | l = list; |
| 628 | offset = fromIndex; |
| 629 | size = toIndex - fromIndex; |
| 630 | this.modCount = l.modCount; |
| 631 | } |
| 632 | |
| 633 | public E set(int index, E element) { |
| 634 | rangeCheck(index); |
| 635 | checkForComodification(); |
| 636 | return l.set(index+offset, element); |
| 637 | } |
| 638 | |
| 639 | public E get(int index) { |
| 640 | rangeCheck(index); |
| 641 | checkForComodification(); |
| 642 | return l.get(index+offset); |
| 643 | } |
| 644 | |
| 645 | public int size() { |
| 646 | checkForComodification(); |
| 647 | return size; |
| 648 | } |
| 649 | |
| 650 | public void add(int index, E element) { |
| 651 | rangeCheckForAdd(index); |
| 652 | checkForComodification(); |
| 653 | l.add(index+offset, element); |
| 654 | this.modCount = l.modCount; |
| 655 | size++; |
| 656 | } |
| 657 | |
| 658 | public E remove(int index) { |
| 659 | rangeCheck(index); |
| 660 | checkForComodification(); |
| 661 | E result = l.remove(index+offset); |
| 662 | this.modCount = l.modCount; |
| 663 | size--; |
| 664 | return result; |
| 665 | } |
| 666 | |
| 667 | protected void removeRange(int fromIndex, int toIndex) { |
| 668 | checkForComodification(); |
| 669 | l.removeRange(fromIndex+offset, toIndex+offset); |
| 670 | this.modCount = l.modCount; |
| 671 | size -= (toIndex-fromIndex); |
| 672 | } |
| 673 | |
| 674 | public boolean addAll(Collection<? extends E> c) { |
| 675 | return addAll(size, c); |
| 676 | } |
| 677 | |
| 678 | public boolean addAll(int index, Collection<? extends E> c) { |
| 679 | rangeCheckForAdd(index); |
| 680 | int cSize = c.size(); |
| 681 | if (cSize==0) |
| 682 | return false; |
| 683 | |
| 684 | checkForComodification(); |
| 685 | l.addAll(offset+index, c); |
| 686 | this.modCount = l.modCount; |
| 687 | size += cSize; |
| 688 | return true; |
| 689 | } |
| 690 | |
| 691 | public Iterator<E> iterator() { |
| 692 | return listIterator(); |
| 693 | } |
| 694 | |
| 695 | public ListIterator<E> listIterator(final int index) { |
| 696 | checkForComodification(); |
| 697 | rangeCheckForAdd(index); |
| 698 | |
| 699 | return new ListIterator<E>() { |
| 700 | private final ListIterator<E> i = l.listIterator(index+offset); |
| 701 | |
| 702 | public boolean hasNext() { |
| 703 | return nextIndex() < size; |
| 704 | } |
| 705 | |
| 706 | public E next() { |
| 707 | if (hasNext()) |
| 708 | return i.next(); |
| 709 | else |
| 710 | throw new NoSuchElementException(); |
| 711 | } |
| 712 | |
| 713 | public boolean hasPrevious() { |
| 714 | return previousIndex() >= 0; |
| 715 | } |
| 716 | |
| 717 | public E previous() { |
| 718 | if (hasPrevious()) |
| 719 | return i.previous(); |
| 720 | else |
| 721 | throw new NoSuchElementException(); |
| 722 | } |
| 723 | |
| 724 | public int nextIndex() { |
| 725 | return i.nextIndex() - offset; |
| 726 | } |
| 727 | |
| 728 | public int previousIndex() { |
| 729 | return i.previousIndex() - offset; |
| 730 | } |
| 731 | |
| 732 | public void remove() { |
| 733 | i.remove(); |
| 734 | SubList.this.modCount = l.modCount; |
| 735 | size--; |
| 736 | } |
| 737 | |
| 738 | public void set(E e) { |
| 739 | i.set(e); |
| 740 | } |
| 741 | |
| 742 | public void add(E e) { |
| 743 | i.add(e); |
| 744 | SubList.this.modCount = l.modCount; |
| 745 | size++; |
| 746 | } |
| 747 | }; |
| 748 | } |
| 749 | |
| 750 | public List<E> subList(int fromIndex, int toIndex) { |
| 751 | return new SubList<E>(this, fromIndex, toIndex); |
| 752 | } |
| 753 | |
| 754 | private void rangeCheck(int index) { |
| 755 | if (index < 0 || index >= size) |
| 756 | throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); |
| 757 | } |
| 758 | |
| 759 | private void rangeCheckForAdd(int index) { |
| 760 | if (index < 0 || index > size) |
| 761 | throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); |
| 762 | } |
| 763 | |
| 764 | private String outOfBoundsMsg(int index) { |
| 765 | return "Index: "+index+", Size: "+size; |
| 766 | } |
| 767 | |
| 768 | private void checkForComodification() { |
| 769 | if (this.modCount != l.modCount) |
| 770 | throw new ConcurrentModificationException(); |
| 771 | } |
| 772 | } |
| 773 | |
| 774 | class RandomAccessSubList<E> extends SubList<E> implements RandomAccess { |
| 775 | RandomAccessSubList(AbstractList<E> list, int fromIndex, int toIndex) { |
| 776 | super(list, fromIndex, toIndex); |
| 777 | } |
| 778 | |
| 779 | public List<E> subList(int fromIndex, int toIndex) { |
| 780 | return new RandomAccessSubList<E>(this, fromIndex, toIndex); |
| 781 | } |
| 782 | } |