J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 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 sun.awt.util; |
| 27 | |
| 28 | import java.util.AbstractList; |
| 29 | import java.util.Arrays; |
| 30 | import java.util.Collection; |
| 31 | import java.util.ConcurrentModificationException; |
| 32 | import java.util.List; |
| 33 | import java.util.RandomAccess; |
| 34 | |
| 35 | /** |
| 36 | * Resizable-array implementation of the <tt>List</tt> interface. Implements |
| 37 | * all optional list operations, and permits all elements, including |
| 38 | * <tt>null</tt>. In addition to implementing the <tt>List</tt> interface, |
| 39 | * this class provides methods to manipulate the size of the array that is |
| 40 | * used internally to store the list. (This class is roughly equivalent to |
| 41 | * <tt>Vector</tt>, except that it is unsynchronized.)<p> |
| 42 | * |
| 43 | * The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>, |
| 44 | * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant |
| 45 | * time. The <tt>add</tt> operation runs in <i>amortized constant time</i>, |
| 46 | * that is, adding n elements requires O(n) time. All of the other operations |
| 47 | * run in linear time (roughly speaking). The constant factor is low compared |
| 48 | * to that for the <tt>LinkedList</tt> implementation.<p> |
| 49 | * |
| 50 | * Each <tt>IdentityArrayList</tt> instance has a <i>capacity</i>. The capacity is |
| 51 | * the size of the array used to store the elements in the list. It is always |
| 52 | * at least as large as the list size. As elements are added to an IdentityArrayList, |
| 53 | * its capacity grows automatically. The details of the growth policy are not |
| 54 | * specified beyond the fact that adding an element has constant amortized |
| 55 | * time cost.<p> |
| 56 | * |
| 57 | * An application can increase the capacity of an <tt>IdentityArrayList</tt> instance |
| 58 | * before adding a large number of elements using the <tt>ensureCapacity</tt> |
| 59 | * operation. This may reduce the amount of incremental reallocation. |
| 60 | * |
| 61 | * <p><strong>Note that this implementation is not synchronized.</strong> |
| 62 | * If multiple threads access an <tt>IdentityArrayList</tt> instance concurrently, |
| 63 | * and at least one of the threads modifies the list structurally, it |
| 64 | * <i>must</i> be synchronized externally. (A structural modification is |
| 65 | * any operation that adds or deletes one or more elements, or explicitly |
| 66 | * resizes the backing array; merely setting the value of an element is not |
| 67 | * a structural modification.) This is typically accomplished by |
| 68 | * synchronizing on some object that naturally encapsulates the list. |
| 69 | * |
| 70 | * If no such object exists, the list should be "wrapped" using the |
| 71 | * {@link Collections#synchronizedList Collections.synchronizedList} |
| 72 | * method. This is best done at creation time, to prevent accidental |
| 73 | * unsynchronized access to the list:<pre> |
| 74 | * List list = Collections.synchronizedList(new IdentityArrayList(...));</pre> |
| 75 | * |
| 76 | * <p>The iterators returned by this class's <tt>iterator</tt> and |
| 77 | * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is |
| 78 | * structurally modified at any time after the iterator is created, in any way |
| 79 | * except through the iterator's own <tt>remove</tt> or <tt>add</tt> methods, |
| 80 | * the iterator will throw a {@link ConcurrentModificationException}. Thus, in |
| 81 | * the face of concurrent modification, the iterator fails quickly and cleanly, |
| 82 | * rather than risking arbitrary, non-deterministic behavior at an undetermined |
| 83 | * time in the future.<p> |
| 84 | * |
| 85 | * Note that the fail-fast behavior of an iterator cannot be guaranteed |
| 86 | * as it is, generally speaking, impossible to make any hard guarantees in the |
| 87 | * presence of unsynchronized concurrent modification. Fail-fast iterators |
| 88 | * throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
| 89 | * Therefore, it would be wrong to write a program that depended on this |
| 90 | * exception for its correctness: <i>the fail-fast behavior of iterators |
| 91 | * should be used only to detect bugs.</i><p> |
| 92 | * |
| 93 | */ |
| 94 | |
| 95 | public class IdentityArrayList<E> extends AbstractList<E> |
| 96 | implements List<E>, RandomAccess |
| 97 | { |
| 98 | |
| 99 | /** |
| 100 | * The array buffer into which the elements of the IdentityArrayList are stored. |
| 101 | * The capacity of the IdentityArrayList is the length of this array buffer. |
| 102 | */ |
| 103 | private transient Object[] elementData; |
| 104 | |
| 105 | /** |
| 106 | * The size of the IdentityArrayList (the number of elements it contains). |
| 107 | * |
| 108 | * @serial |
| 109 | */ |
| 110 | private int size; |
| 111 | |
| 112 | /** |
| 113 | * Constructs an empty list with the specified initial capacity. |
| 114 | * |
| 115 | * @param initialCapacity the initial capacity of the list |
| 116 | * @exception IllegalArgumentException if the specified initial capacity |
| 117 | * is negative |
| 118 | */ |
| 119 | public IdentityArrayList(int initialCapacity) { |
| 120 | super(); |
| 121 | if (initialCapacity < 0) |
| 122 | throw new IllegalArgumentException("Illegal Capacity: "+ |
| 123 | initialCapacity); |
| 124 | this.elementData = new Object[initialCapacity]; |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * Constructs an empty list with an initial capacity of ten. |
| 129 | */ |
| 130 | public IdentityArrayList() { |
| 131 | this(10); |
| 132 | } |
| 133 | |
| 134 | /** |
| 135 | * Constructs a list containing the elements of the specified |
| 136 | * collection, in the order they are returned by the collection's |
| 137 | * iterator. |
| 138 | * |
| 139 | * @param c the collection whose elements are to be placed into this list |
| 140 | * @throws NullPointerException if the specified collection is null |
| 141 | */ |
| 142 | public IdentityArrayList(Collection<? extends E> c) { |
| 143 | elementData = c.toArray(); |
| 144 | size = elementData.length; |
| 145 | // c.toArray might (incorrectly) not return Object[] (see 6260652) |
| 146 | if (elementData.getClass() != Object[].class) |
| 147 | elementData = Arrays.copyOf(elementData, size, Object[].class); |
| 148 | } |
| 149 | |
| 150 | /** |
| 151 | * Trims the capacity of this <tt>IdentityArrayList</tt> instance to be the |
| 152 | * list's current size. An application can use this operation to minimize |
| 153 | * the storage of an <tt>IdentityArrayList</tt> instance. |
| 154 | */ |
| 155 | public void trimToSize() { |
| 156 | modCount++; |
| 157 | int oldCapacity = elementData.length; |
| 158 | if (size < oldCapacity) { |
| 159 | elementData = Arrays.copyOf(elementData, size); |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | /** |
| 164 | * Increases the capacity of this <tt>IdentityArrayList</tt> instance, if |
| 165 | * necessary, to ensure that it can hold at least the number of elements |
| 166 | * specified by the minimum capacity argument. |
| 167 | * |
| 168 | * @param minCapacity the desired minimum capacity |
| 169 | */ |
| 170 | public void ensureCapacity(int minCapacity) { |
| 171 | modCount++; |
| 172 | int oldCapacity = elementData.length; |
| 173 | if (minCapacity > oldCapacity) { |
| 174 | Object oldData[] = elementData; |
| 175 | int newCapacity = (oldCapacity * 3)/2 + 1; |
| 176 | if (newCapacity < minCapacity) |
| 177 | newCapacity = minCapacity; |
| 178 | // minCapacity is usually close to size, so this is a win: |
| 179 | elementData = Arrays.copyOf(elementData, newCapacity); |
| 180 | } |
| 181 | } |
| 182 | |
| 183 | /** |
| 184 | * Returns the number of elements in this list. |
| 185 | * |
| 186 | * @return the number of elements in this list |
| 187 | */ |
| 188 | public int size() { |
| 189 | return size; |
| 190 | } |
| 191 | |
| 192 | /** |
| 193 | * Returns <tt>true</tt> if this list contains no elements. |
| 194 | * |
| 195 | * @return <tt>true</tt> if this list contains no elements |
| 196 | */ |
| 197 | public boolean isEmpty() { |
| 198 | return size == 0; |
| 199 | } |
| 200 | |
| 201 | /** |
| 202 | * Returns <tt>true</tt> if this list contains the specified element. |
| 203 | * More formally, returns <tt>true</tt> if and only if this list contains |
| 204 | * at least one element <tt>e</tt> such that |
| 205 | * <tt>(o==null ? e==null : o == e)</tt>. |
| 206 | * |
| 207 | * @param o element whose presence in this list is to be tested |
| 208 | * @return <tt>true</tt> if this list contains the specified element |
| 209 | */ |
| 210 | public boolean contains(Object o) { |
| 211 | return indexOf(o) >= 0; |
| 212 | } |
| 213 | |
| 214 | /** |
| 215 | * Returns the index of the first occurrence of the specified element |
| 216 | * in this list, or -1 if this list does not contain the element. |
| 217 | * More formally, returns the lowest index <tt>i</tt> such that |
| 218 | * <tt>(o==null ? get(i)==null : o == get(i))</tt>, |
| 219 | * or -1 if there is no such index. |
| 220 | */ |
| 221 | public int indexOf(Object o) { |
| 222 | for (int i = 0; i < size; i++) { |
| 223 | if (o == elementData[i]) { |
| 224 | return i; |
| 225 | } |
| 226 | } |
| 227 | return -1; |
| 228 | } |
| 229 | |
| 230 | /** |
| 231 | * Returns the index of the last occurrence of the specified element |
| 232 | * in this list, or -1 if this list does not contain the element. |
| 233 | * More formally, returns the highest index <tt>i</tt> such that |
| 234 | * <tt>(o==null ? get(i)==null : o == get(i))</tt>, |
| 235 | * or -1 if there is no such index. |
| 236 | */ |
| 237 | public int lastIndexOf(Object o) { |
| 238 | for (int i = size-1; i >= 0; i--) { |
| 239 | if (o == elementData[i]) { |
| 240 | return i; |
| 241 | } |
| 242 | } |
| 243 | return -1; |
| 244 | } |
| 245 | |
| 246 | /** |
| 247 | * Returns an array containing all of the elements in this list |
| 248 | * in proper sequence (from first to last element). |
| 249 | * |
| 250 | * <p>The returned array will be "safe" in that no references to it are |
| 251 | * maintained by this list. (In other words, this method must allocate |
| 252 | * a new array). The caller is thus free to modify the returned array. |
| 253 | * |
| 254 | * <p>This method acts as bridge between array-based and collection-based |
| 255 | * APIs. |
| 256 | * |
| 257 | * @return an array containing all of the elements in this list in |
| 258 | * proper sequence |
| 259 | */ |
| 260 | public Object[] toArray() { |
| 261 | return Arrays.copyOf(elementData, size); |
| 262 | } |
| 263 | |
| 264 | /** |
| 265 | * Returns an array containing all of the elements in this list in proper |
| 266 | * sequence (from first to last element); the runtime type of the returned |
| 267 | * array is that of the specified array. If the list fits in the |
| 268 | * specified array, it is returned therein. Otherwise, a new array is |
| 269 | * allocated with the runtime type of the specified array and the size of |
| 270 | * this list. |
| 271 | * |
| 272 | * <p>If the list fits in the specified array with room to spare |
| 273 | * (i.e., the array has more elements than the list), the element in |
| 274 | * the array immediately following the end of the collection is set to |
| 275 | * <tt>null</tt>. (This is useful in determining the length of the |
| 276 | * list <i>only</i> if the caller knows that the list does not contain |
| 277 | * any null elements.) |
| 278 | * |
| 279 | * @param a the array into which the elements of the list are to |
| 280 | * be stored, if it is big enough; otherwise, a new array of the |
| 281 | * same runtime type is allocated for this purpose. |
| 282 | * @return an array containing the elements of the list |
| 283 | * @throws ArrayStoreException if the runtime type of the specified array |
| 284 | * is not a supertype of the runtime type of every element in |
| 285 | * this list |
| 286 | * @throws NullPointerException if the specified array is null |
| 287 | */ |
| 288 | public <T> T[] toArray(T[] a) { |
| 289 | if (a.length < size) |
| 290 | // Make a new array of a's runtime type, but my contents: |
| 291 | return (T[]) Arrays.copyOf(elementData, size, a.getClass()); |
| 292 | System.arraycopy(elementData, 0, a, 0, size); |
| 293 | if (a.length > size) |
| 294 | a[size] = null; |
| 295 | return a; |
| 296 | } |
| 297 | |
| 298 | // Positional Access Operations |
| 299 | |
| 300 | /** |
| 301 | * Returns the element at the specified position in this list. |
| 302 | * |
| 303 | * @param index index of the element to return |
| 304 | * @return the element at the specified position in this list |
| 305 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 306 | */ |
| 307 | public E get(int index) { |
| 308 | rangeCheck(index); |
| 309 | |
| 310 | return (E) elementData[index]; |
| 311 | } |
| 312 | |
| 313 | /** |
| 314 | * Replaces the element at the specified position in this list with |
| 315 | * the specified element. |
| 316 | * |
| 317 | * @param index index of the element to replace |
| 318 | * @param element element to be stored at the specified position |
| 319 | * @return the element previously at the specified position |
| 320 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 321 | */ |
| 322 | public E set(int index, E element) { |
| 323 | rangeCheck(index); |
| 324 | |
| 325 | E oldValue = (E) elementData[index]; |
| 326 | elementData[index] = element; |
| 327 | return oldValue; |
| 328 | } |
| 329 | |
| 330 | /** |
| 331 | * Appends the specified element to the end of this list. |
| 332 | * |
| 333 | * @param e element to be appended to this list |
| 334 | * @return <tt>true</tt> (as specified by {@link Collection#add}) |
| 335 | */ |
| 336 | public boolean add(E e) { |
| 337 | ensureCapacity(size + 1); // Increments modCount!! |
| 338 | elementData[size++] = e; |
| 339 | return true; |
| 340 | } |
| 341 | |
| 342 | /** |
| 343 | * Inserts the specified element at the specified position in this |
| 344 | * list. Shifts the element currently at that position (if any) and |
| 345 | * any subsequent elements to the right (adds one to their indices). |
| 346 | * |
| 347 | * @param index index at which the specified element is to be inserted |
| 348 | * @param element element to be inserted |
| 349 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 350 | */ |
| 351 | public void add(int index, E element) { |
| 352 | rangeCheckForAdd(index); |
| 353 | |
| 354 | ensureCapacity(size+1); // Increments modCount!! |
| 355 | System.arraycopy(elementData, index, elementData, index + 1, |
| 356 | size - index); |
| 357 | elementData[index] = element; |
| 358 | size++; |
| 359 | } |
| 360 | |
| 361 | /** |
| 362 | * Removes the element at the specified position in this list. |
| 363 | * Shifts any subsequent elements to the left (subtracts one from their |
| 364 | * indices). |
| 365 | * |
| 366 | * @param index the index of the element to be removed |
| 367 | * @return the element that was removed from the list |
| 368 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 369 | */ |
| 370 | public E remove(int index) { |
| 371 | rangeCheck(index); |
| 372 | |
| 373 | modCount++; |
| 374 | E oldValue = (E) elementData[index]; |
| 375 | |
| 376 | int numMoved = size - index - 1; |
| 377 | if (numMoved > 0) |
| 378 | System.arraycopy(elementData, index+1, elementData, index, |
| 379 | numMoved); |
| 380 | elementData[--size] = null; // Let gc do its work |
| 381 | |
| 382 | return oldValue; |
| 383 | } |
| 384 | |
| 385 | /** |
| 386 | * Removes the first occurrence of the specified element from this list, |
| 387 | * if it is present. If the list does not contain the element, it is |
| 388 | * unchanged. More formally, removes the element with the lowest index |
| 389 | * <tt>i</tt> such that |
| 390 | * <tt>(o==null ? get(i)==null : o == get(i))</tt> |
| 391 | * (if such an element exists). Returns <tt>true</tt> if this list |
| 392 | * contained the specified element (or equivalently, if this list |
| 393 | * changed as a result of the call). |
| 394 | * |
| 395 | * @param o element to be removed from this list, if present |
| 396 | * @return <tt>true</tt> if this list contained the specified element |
| 397 | */ |
| 398 | public boolean remove(Object o) { |
| 399 | for (int index = 0; index < size; index++) { |
| 400 | if (o == elementData[index]) { |
| 401 | fastRemove(index); |
| 402 | return true; |
| 403 | } |
| 404 | } |
| 405 | return false; |
| 406 | } |
| 407 | |
| 408 | /* |
| 409 | * Private remove method that skips bounds checking and does not |
| 410 | * return the value removed. |
| 411 | */ |
| 412 | private void fastRemove(int index) { |
| 413 | modCount++; |
| 414 | int numMoved = size - index - 1; |
| 415 | if (numMoved > 0) |
| 416 | System.arraycopy(elementData, index+1, elementData, index, |
| 417 | numMoved); |
| 418 | elementData[--size] = null; // Let gc do its work |
| 419 | } |
| 420 | |
| 421 | /** |
| 422 | * Removes all of the elements from this list. The list will |
| 423 | * be empty after this call returns. |
| 424 | */ |
| 425 | public void clear() { |
| 426 | modCount++; |
| 427 | |
| 428 | // Let gc do its work |
| 429 | for (int i = 0; i < size; i++) |
| 430 | elementData[i] = null; |
| 431 | |
| 432 | size = 0; |
| 433 | } |
| 434 | |
| 435 | /** |
| 436 | * Appends all of the elements in the specified collection to the end of |
| 437 | * this list, in the order that they are returned by the |
| 438 | * specified collection's Iterator. The behavior of this operation is |
| 439 | * undefined if the specified collection is modified while the operation |
| 440 | * is in progress. (This implies that the behavior of this call is |
| 441 | * undefined if the specified collection is this list, and this |
| 442 | * list is nonempty.) |
| 443 | * |
| 444 | * @param c collection containing elements to be added to this list |
| 445 | * @return <tt>true</tt> if this list changed as a result of the call |
| 446 | * @throws NullPointerException if the specified collection is null |
| 447 | */ |
| 448 | public boolean addAll(Collection<? extends E> c) { |
| 449 | Object[] a = c.toArray(); |
| 450 | int numNew = a.length; |
| 451 | ensureCapacity(size + numNew); // Increments modCount |
| 452 | System.arraycopy(a, 0, elementData, size, numNew); |
| 453 | size += numNew; |
| 454 | return numNew != 0; |
| 455 | } |
| 456 | |
| 457 | /** |
| 458 | * Inserts all of the elements in the specified collection into this |
| 459 | * list, starting at the specified position. Shifts the element |
| 460 | * currently at that position (if any) and any subsequent elements to |
| 461 | * the right (increases their indices). The new elements will appear |
| 462 | * in the list in the order that they are returned by the |
| 463 | * specified collection's iterator. |
| 464 | * |
| 465 | * @param index index at which to insert the first element from the |
| 466 | * specified collection |
| 467 | * @param c collection containing elements to be added to this list |
| 468 | * @return <tt>true</tt> if this list changed as a result of the call |
| 469 | * @throws IndexOutOfBoundsException {@inheritDoc} |
| 470 | * @throws NullPointerException if the specified collection is null |
| 471 | */ |
| 472 | public boolean addAll(int index, Collection<? extends E> c) { |
| 473 | rangeCheckForAdd(index); |
| 474 | |
| 475 | Object[] a = c.toArray(); |
| 476 | int numNew = a.length; |
| 477 | ensureCapacity(size + numNew); // Increments modCount |
| 478 | |
| 479 | int numMoved = size - index; |
| 480 | if (numMoved > 0) { |
| 481 | System.arraycopy(elementData, index, elementData, index + numNew, numMoved); |
| 482 | } |
| 483 | |
| 484 | System.arraycopy(a, 0, elementData, index, numNew); |
| 485 | size += numNew; |
| 486 | return numNew != 0; |
| 487 | } |
| 488 | |
| 489 | /** |
| 490 | * Removes from this list all of the elements whose index is between |
| 491 | * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
| 492 | * Shifts any succeeding elements to the left (reduces their index). |
| 493 | * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements. |
| 494 | * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.) |
| 495 | * |
| 496 | * @param fromIndex index of first element to be removed |
| 497 | * @param toIndex index after last element to be removed |
| 498 | * @throws IndexOutOfBoundsException if fromIndex or toIndex out of |
| 499 | * range (fromIndex < 0 || fromIndex >= size() || toIndex |
| 500 | * > size() || toIndex < fromIndex) |
| 501 | */ |
| 502 | protected void removeRange(int fromIndex, int toIndex) { |
| 503 | modCount++; |
| 504 | int numMoved = size - toIndex; |
| 505 | System.arraycopy(elementData, toIndex, elementData, fromIndex, |
| 506 | numMoved); |
| 507 | |
| 508 | // Let gc do its work |
| 509 | int newSize = size - (toIndex-fromIndex); |
| 510 | while (size != newSize) |
| 511 | elementData[--size] = null; |
| 512 | } |
| 513 | |
| 514 | /** |
| 515 | * Checks if the given index is in range. If not, throws an appropriate |
| 516 | * runtime exception. This method does *not* check if the index is |
| 517 | * negative: It is always used immediately prior to an array access, |
| 518 | * which throws an ArrayIndexOutOfBoundsException if index is negative. |
| 519 | */ |
| 520 | private void rangeCheck(int index) { |
| 521 | if (index >= size) |
| 522 | throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); |
| 523 | } |
| 524 | |
| 525 | /** |
| 526 | * A version of rangeCheck used by add and addAll. |
| 527 | */ |
| 528 | private void rangeCheckForAdd(int index) { |
| 529 | if (index > size || index < 0) |
| 530 | throw new IndexOutOfBoundsException(outOfBoundsMsg(index)); |
| 531 | } |
| 532 | |
| 533 | /** |
| 534 | * Constructs an IndexOutOfBoundsException detail message. |
| 535 | * Of the many possible refactorings of the error handling code, |
| 536 | * this "outlining" performs best with both server and client VMs. |
| 537 | */ |
| 538 | private String outOfBoundsMsg(int index) { |
| 539 | return "Index: "+index+", Size: "+size; |
| 540 | } |
| 541 | } |