1 /* 2 * Copyright (c) 1994, 2008, 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 * The {@code Vector} class implements a growable array of 30 * objects. Like an array, it contains components that can be 31 * accessed using an integer index. However, the size of a 32 * {@code Vector} can grow or shrink as needed to accommodate 33 * adding and removing items after the {@code Vector} has been created. 34 * 35 * <p>Each vector tries to optimize storage management by maintaining a 36 * {@code capacity} and a {@code capacityIncrement}. The 37 * {@code capacity} is always at least as large as the vector 38 * size; it is usually larger because as components are added to the 39 * vector, the vector's storage increases in chunks the size of 40 * {@code capacityIncrement}. An application can increase the 41 * capacity of a vector before inserting a large number of 42 * components; this reduces the amount of incremental reallocation. 43 * 44 * <p><a name="fail-fast"/> 45 * The iterators returned by this class's {@link #iterator() iterator} and 46 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>: 47 * if the vector is structurally modified at any time after the iterator is 48 * created, in any way except through the iterator's own 49 * {@link ListIterator#remove() remove} or 50 * {@link ListIterator#add(Object) add} methods, the iterator will throw a 51 * {@link ConcurrentModificationException}. Thus, in the face of 52 * concurrent modification, the iterator fails quickly and cleanly, rather 53 * than risking arbitrary, non-deterministic behavior at an undetermined 54 * time in the future. The {@link Enumeration Enumerations} returned by 55 * the {@link #elements() elements} method are <em>not</em> fail-fast. 56 * 57 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed 58 * as it is, generally speaking, impossible to make any hard guarantees in the 59 * presence of unsynchronized concurrent modification. Fail-fast iterators 60 * throw {@code ConcurrentModificationException} on a best-effort basis. 61 * Therefore, it would be wrong to write a program that depended on this 62 * exception for its correctness: <i>the fail-fast behavior of iterators 63 * should be used only to detect bugs.</i> 64 * 65 * <p>As of the Java 2 platform v1.2, this class was retrofitted to 66 * implement the {@link List} interface, making it a member of the 67 * <a href="{@docRoot}/../technotes/guides/collections/index.html"> 68 * Java Collections Framework</a>. Unlike the new collection 69 * implementations, {@code Vector} is synchronized. If a thread-safe 70 * implementation is not needed, it is recommended to use {@link 71 * ArrayList} in place of {@code Vector}. 72 * 73 * @author Lee Boynton 74 * @author Jonathan Payne 75 * @see Collection 76 * @see LinkedList 77 * @since JDK1.0 78 */ 79 public class Vector<E> 80 extends AbstractList<E> 81 implements List<E>, RandomAccess, Cloneable, java.io.Serializable 82 { 83 /** 84 * The array buffer into which the components of the vector are 85 * stored. The capacity of the vector is the length of this array buffer, 86 * and is at least large enough to contain all the vector's elements. 87 * 88 * <p>Any array elements following the last element in the Vector are null. 89 * 90 * @serial 91 */ 92 protected Object[] elementData; 93 94 /** 95 * The number of valid components in this {@code Vector} object. 96 * Components {@code elementData[0]} through 97 * {@code elementData[elementCount-1]} are the actual items. 98 * 99 * @serial 100 */ 101 protected int elementCount; 102 103 /** 104 * The amount by which the capacity of the vector is automatically 105 * incremented when its size becomes greater than its capacity. If 106 * the capacity increment is less than or equal to zero, the capacity 107 * of the vector is doubled each time it needs to grow. 108 * 109 * @serial 110 */ 111 protected int capacityIncrement; 112 113 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 114 private static final long serialVersionUID = -2767605614048989439L; 115 116 /** 117 * Constructs an empty vector with the specified initial capacity and 118 * capacity increment. 119 * 120 * @param initialCapacity the initial capacity of the vector 121 * @param capacityIncrement the amount by which the capacity is 122 * increased when the vector overflows 123 * @throws IllegalArgumentException if the specified initial capacity 124 * is negative 125 */ 126 public Vector(int initialCapacity, int capacityIncrement) { 127 super(); 128 if (initialCapacity < 0) 129 throw new IllegalArgumentException("Illegal Capacity: "+ 130 initialCapacity); 131 this.elementData = new Object[initialCapacity]; 132 this.capacityIncrement = capacityIncrement; 133 } 134 135 /** 136 * Constructs an empty vector with the specified initial capacity and 137 * with its capacity increment equal to zero. 138 * 139 * @param initialCapacity the initial capacity of the vector 140 * @throws IllegalArgumentException if the specified initial capacity 141 * is negative 142 */ 143 public Vector(int initialCapacity) { 144 this(initialCapacity, 0); 145 } 146 147 /** 148 * Constructs an empty vector so that its internal data array 149 * has size {@code 10} and its standard capacity increment is 150 * zero. 151 */ 152 public Vector() { 153 this(10); 154 } 155 156 /** 157 * Constructs a vector containing the elements of the specified 158 * collection, in the order they are returned by the collection's 159 * iterator. 160 * 161 * @param c the collection whose elements are to be placed into this 162 * vector 163 * @throws NullPointerException if the specified collection is null 164 * @since 1.2 165 */ 166 public Vector(Collection<? extends E> c) { 167 elementData = c.toArray(); 168 elementCount = elementData.length; 169 // c.toArray might (incorrectly) not return Object[] (see 6260652) 170 if (elementData.getClass() != Object[].class) 171 elementData = Arrays.copyOf(elementData, elementCount, Object[].class); 172 } 173 174 /** 175 * Copies the components of this vector into the specified array. 176 * The item at index {@code k} in this vector is copied into 177 * component {@code k} of {@code anArray}. 178 * 179 * @param anArray the array into which the components get copied 180 * @throws NullPointerException if the given array is null 181 * @throws IndexOutOfBoundsException if the specified array is not 182 * large enough to hold all the components of this vector 183 * @throws ArrayStoreException if a component of this vector is not of 184 * a runtime type that can be stored in the specified array 185 * @see #toArray(Object[]) 186 */ 187 public synchronized void copyInto(Object[] anArray) { 188 System.arraycopy(elementData, 0, anArray, 0, elementCount); 189 } 190 191 /** 192 * Trims the capacity of this vector to be the vector's current 193 * size. If the capacity of this vector is larger than its current 194 * size, then the capacity is changed to equal the size by replacing 195 * its internal data array, kept in the field {@code elementData}, 196 * with a smaller one. An application can use this operation to 197 * minimize the storage of a vector. 198 */ 199 public synchronized void trimToSize() { 200 modCount++; 201 int oldCapacity = elementData.length; 202 if (elementCount < oldCapacity) { 203 elementData = Arrays.copyOf(elementData, elementCount); 204 } 205 } 206 207 /** 208 * Increases the capacity of this vector, if necessary, to ensure 209 * that it can hold at least the number of components specified by 210 * the minimum capacity argument. 211 * 212 * <p>If the current capacity of this vector is less than 213 * {@code minCapacity}, then its capacity is increased by replacing its 214 * internal data array, kept in the field {@code elementData}, with a 215 * larger one. The size of the new data array will be the old size plus 216 * {@code capacityIncrement}, unless the value of 217 * {@code capacityIncrement} is less than or equal to zero, in which case 218 * the new capacity will be twice the old capacity; but if this new size 219 * is still smaller than {@code minCapacity}, then the new capacity will 220 * be {@code minCapacity}. 221 * 222 * @param minCapacity the desired minimum capacity 223 */ 224 public synchronized void ensureCapacity(int minCapacity) { 225 if (minCapacity > 0) { 226 modCount++; 227 ensureCapacityHelper(minCapacity); 228 } 229 } 230 231 /** 232 * This implements the unsynchronized semantics of ensureCapacity. 233 * Synchronized methods in this class can internally call this 234 * method for ensuring capacity without incurring the cost of an 235 * extra synchronization. 236 * 237 * @see #ensureCapacity(int) 238 */ 239 private void ensureCapacityHelper(int minCapacity) { 240 // overflow-conscious code 241 if (minCapacity - elementData.length > 0) 242 grow(minCapacity); 243 } 244 245 /** 246 * The maximum size of array to allocate. 247 * Some VMs reserve some header words in an array. 248 * Attempts to allocate larger arrays may result in 249 * OutOfMemoryError: Requested array size exceeds VM limit 250 */ 251 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; 252 253 private void grow(int minCapacity) { 254 // overflow-conscious code 255 int oldCapacity = elementData.length; 256 int newCapacity = oldCapacity + ((capacityIncrement > 0) ? 257 capacityIncrement : oldCapacity); 258 if (newCapacity - minCapacity < 0) 259 newCapacity = minCapacity; 260 if (newCapacity - MAX_ARRAY_SIZE > 0) 261 newCapacity = hugeCapacity(minCapacity); 262 elementData = Arrays.copyOf(elementData, newCapacity); 263 } 264 265 private static int hugeCapacity(int minCapacity) { 266 if (minCapacity < 0) // overflow 267 throw new OutOfMemoryError(); 268 return (minCapacity > MAX_ARRAY_SIZE) ? 269 Integer.MAX_VALUE : 270 MAX_ARRAY_SIZE; 271 } 272 273 /** 274 * Sets the size of this vector. If the new size is greater than the 275 * current size, new {@code null} items are added to the end of 276 * the vector. If the new size is less than the current size, all 277 * components at index {@code newSize} and greater are discarded. 278 * 279 * @param newSize the new size of this vector 280 * @throws ArrayIndexOutOfBoundsException if the new size is negative 281 */ 282 public synchronized void setSize(int newSize) { 283 modCount++; 284 if (newSize > elementCount) { 285 ensureCapacityHelper(newSize); 286 } else { 287 for (int i = newSize ; i < elementCount ; i++) { 288 elementData[i] = null; 289 } 290 } 291 elementCount = newSize; 292 } 293 294 /** 295 * Returns the current capacity of this vector. 296 * 297 * @return the current capacity (the length of its internal 298 * data array, kept in the field {@code elementData} 299 * of this vector) 300 */ 301 public synchronized int capacity() { 302 return elementData.length; 303 } 304 305 /** 306 * Returns the number of components in this vector. 307 * 308 * @return the number of components in this vector 309 */ 310 public synchronized int size() { 311 return elementCount; 312 } 313 314 /** 315 * Tests if this vector has no components. 316 * 317 * @return {@code true} if and only if this vector has 318 * no components, that is, its size is zero; 319 * {@code false} otherwise. 320 */ 321 public synchronized boolean isEmpty() { 322 return elementCount == 0; 323 } 324 325 /** 326 * Returns an enumeration of the components of this vector. The 327 * returned {@code Enumeration} object will generate all items in 328 * this vector. The first item generated is the item at index {@code 0}, 329 * then the item at index {@code 1}, and so on. 330 * 331 * @return an enumeration of the components of this vector 332 * @see Iterator 333 */ 334 public Enumeration<E> elements() { 335 return new Enumeration<E>() { 336 int count = 0; 337 338 public boolean hasMoreElements() { 339 return count < elementCount; 340 } 341 342 public E nextElement() { 343 synchronized (Vector.this) { 344 if (count < elementCount) { 345 return elementData(count++); 346 } 347 } 348 throw new NoSuchElementException("Vector Enumeration"); 349 } 350 }; 351 } 352 353 /** 354 * Returns {@code true} if this vector contains the specified element. 355 * More formally, returns {@code true} if and only if this vector 356 * contains at least one element {@code e} such that 357 * <tt>(o==null ? e==null : o.equals(e))</tt>. 358 * 359 * @param o element whose presence in this vector is to be tested 360 * @return {@code true} if this vector contains the specified element 361 */ 362 public boolean contains(Object o) { 363 return indexOf(o, 0) >= 0; 364 } 365 366 /** 367 * Returns the index of the first occurrence of the specified element 368 * in this vector, or -1 if this vector does not contain the element. 369 * More formally, returns the lowest index {@code i} such that 370 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, 371 * or -1 if there is no such index. 372 * 373 * @param o element to search for 374 * @return the index of the first occurrence of the specified element in 375 * this vector, or -1 if this vector does not contain the element 376 */ 377 public int indexOf(Object o) { 378 return indexOf(o, 0); 379 } 380 381 /** 382 * Returns the index of the first occurrence of the specified element in 383 * this vector, searching forwards from {@code index}, or returns -1 if 384 * the element is not found. 385 * More formally, returns the lowest index {@code i} such that 386 * <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>, 387 * or -1 if there is no such index. 388 * 389 * @param o element to search for 390 * @param index index to start searching from 391 * @return the index of the first occurrence of the element in 392 * this vector at position {@code index} or later in the vector; 393 * {@code -1} if the element is not found. 394 * @throws IndexOutOfBoundsException if the specified index is negative 395 * @see Object#equals(Object) 396 */ 397 public synchronized int indexOf(Object o, int index) { 398 if (o == null) { 399 for (int i = index ; i < elementCount ; i++) 400 if (elementData[i]==null) 401 return i; 402 } else { 403 for (int i = index ; i < elementCount ; i++) 404 if (o.equals(elementData[i])) 405 return i; 406 } 407 return -1; 408 } 409 410 /** 411 * Returns the index of the last occurrence of the specified element 412 * in this vector, or -1 if this vector does not contain the element. 413 * More formally, returns the highest index {@code i} such that 414 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, 415 * or -1 if there is no such index. 416 * 417 * @param o element to search for 418 * @return the index of the last occurrence of the specified element in 419 * this vector, or -1 if this vector does not contain the element 420 */ 421 public synchronized int lastIndexOf(Object o) { 422 return lastIndexOf(o, elementCount-1); 423 } 424 425 /** 426 * Returns the index of the last occurrence of the specified element in 427 * this vector, searching backwards from {@code index}, or returns -1 if 428 * the element is not found. 429 * More formally, returns the highest index {@code i} such that 430 * <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>, 431 * or -1 if there is no such index. 432 * 433 * @param o element to search for 434 * @param index index to start searching backwards from 435 * @return the index of the last occurrence of the element at position 436 * less than or equal to {@code index} in this vector; 437 * -1 if the element is not found. 438 * @throws IndexOutOfBoundsException if the specified index is greater 439 * than or equal to the current size of this vector 440 */ 441 public synchronized int lastIndexOf(Object o, int index) { 442 if (index >= elementCount) 443 throw new IndexOutOfBoundsException(index + " >= "+ elementCount); 444 445 if (o == null) { 446 for (int i = index; i >= 0; i--) 447 if (elementData[i]==null) 448 return i; 449 } else { 450 for (int i = index; i >= 0; i--) 451 if (o.equals(elementData[i])) 452 return i; 453 } 454 return -1; 455 } 456 457 /** 458 * Returns the component at the specified index. 459 * 460 * <p>This method is identical in functionality to the {@link #get(int)} 461 * method (which is part of the {@link List} interface). 462 * 463 * @param index an index into this vector 464 * @return the component at the specified index 465 * @throws ArrayIndexOutOfBoundsException if the index is out of range 466 * ({@code index < 0 || index >= size()}) 467 */ 468 public synchronized E elementAt(int index) { 469 if (index >= elementCount) { 470 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount); 471 } 472 473 return elementData(index); 474 } 475 476 /** 477 * Returns the first component (the item at index {@code 0}) of 478 * this vector. 479 * 480 * @return the first component of this vector 481 * @throws NoSuchElementException if this vector has no components 482 */ 483 public synchronized E firstElement() { 484 if (elementCount == 0) { 485 throw new NoSuchElementException(); 486 } 487 return elementData(0); 488 } 489 490 /** 491 * Returns the last component of the vector. 492 * 493 * @return the last component of the vector, i.e., the component at index 494 * <code>size() - 1</code>. 495 * @throws NoSuchElementException if this vector is empty 496 */ 497 public synchronized E lastElement() { 498 if (elementCount == 0) { 499 throw new NoSuchElementException(); 500 } 501 return elementData(elementCount - 1); 502 } 503 504 /** 505 * Sets the component at the specified {@code index} of this 506 * vector to be the specified object. The previous component at that 507 * position is discarded. 508 * 509 * <p>The index must be a value greater than or equal to {@code 0} 510 * and less than the current size of the vector. 511 * 512 * <p>This method is identical in functionality to the 513 * {@link #set(int, Object) set(int, E)} 514 * method (which is part of the {@link List} interface). Note that the 515 * {@code set} method reverses the order of the parameters, to more closely 516 * match array usage. Note also that the {@code set} method returns the 517 * old value that was stored at the specified position. 518 * 519 * @param obj what the component is to be set to 520 * @param index the specified index 521 * @throws ArrayIndexOutOfBoundsException if the index is out of range 522 * ({@code index < 0 || index >= size()}) 523 */ 524 public synchronized void setElementAt(E obj, int index) { 525 if (index >= elementCount) { 526 throw new ArrayIndexOutOfBoundsException(index + " >= " + 527 elementCount); 528 } 529 elementData[index] = obj; 530 } 531 532 /** 533 * Deletes the component at the specified index. Each component in 534 * this vector with an index greater or equal to the specified 535 * {@code index} is shifted downward to have an index one 536 * smaller than the value it had previously. The size of this vector 537 * is decreased by {@code 1}. 538 * 539 * <p>The index must be a value greater than or equal to {@code 0} 540 * and less than the current size of the vector. 541 * 542 * <p>This method is identical in functionality to the {@link #remove(int)} 543 * method (which is part of the {@link List} interface). Note that the 544 * {@code remove} method returns the old value that was stored at the 545 * specified position. 546 * 547 * @param index the index of the object to remove 548 * @throws ArrayIndexOutOfBoundsException if the index is out of range 549 * ({@code index < 0 || index >= size()}) 550 */ 551 public synchronized void removeElementAt(int index) { 552 modCount++; 553 if (index >= elementCount) { 554 throw new ArrayIndexOutOfBoundsException(index + " >= " + 555 elementCount); 556 } 557 else if (index < 0) { 558 throw new ArrayIndexOutOfBoundsException(index); 559 } 560 int j = elementCount - index - 1; 561 if (j > 0) { 562 System.arraycopy(elementData, index + 1, elementData, index, j); 563 } 564 elementCount--; 565 elementData[elementCount] = null; /* to let gc do its work */ 566 } 567 568 /** 569 * Inserts the specified object as a component in this vector at the 570 * specified {@code index}. Each component in this vector with 571 * an index greater or equal to the specified {@code index} is 572 * shifted upward to have an index one greater than the value it had 573 * previously. 574 * 575 * <p>The index must be a value greater than or equal to {@code 0} 576 * and less than or equal to the current size of the vector. (If the 577 * index is equal to the current size of the vector, the new element 578 * is appended to the Vector.) 579 * 580 * <p>This method is identical in functionality to the 581 * {@link #add(int, Object) add(int, E)} 582 * method (which is part of the {@link List} interface). Note that the 583 * {@code add} method reverses the order of the parameters, to more closely 584 * match array usage. 585 * 586 * @param obj the component to insert 587 * @param index where to insert the new component 588 * @throws ArrayIndexOutOfBoundsException if the index is out of range 589 * ({@code index < 0 || index > size()}) 590 */ 591 public synchronized void insertElementAt(E obj, int index) { 592 modCount++; 593 if (index > elementCount) { 594 throw new ArrayIndexOutOfBoundsException(index 595 + " > " + elementCount); 596 } 597 ensureCapacityHelper(elementCount + 1); 598 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index); 599 elementData[index] = obj; 600 elementCount++; 601 } 602 603 /** 604 * Adds the specified component to the end of this vector, 605 * increasing its size by one. The capacity of this vector is 606 * increased if its size becomes greater than its capacity. 607 * 608 * <p>This method is identical in functionality to the 609 * {@link #add(Object) add(E)} 610 * method (which is part of the {@link List} interface). 611 * 612 * @param obj the component to be added 613 */ 614 public synchronized void addElement(E obj) { 615 modCount++; 616 ensureCapacityHelper(elementCount + 1); 617 elementData[elementCount++] = obj; 618 } 619 620 /** 621 * Removes the first (lowest-indexed) occurrence of the argument 622 * from this vector. If the object is found in this vector, each 623 * component in the vector with an index greater or equal to the 624 * object's index is shifted downward to have an index one smaller 625 * than the value it had previously. 626 * 627 * <p>This method is identical in functionality to the 628 * {@link #remove(Object)} method (which is part of the 629 * {@link List} interface). 630 * 631 * @param obj the component to be removed 632 * @return {@code true} if the argument was a component of this 633 * vector; {@code false} otherwise. 634 */ 635 public synchronized boolean removeElement(Object obj) { 636 modCount++; 637 int i = indexOf(obj); 638 if (i >= 0) { 639 removeElementAt(i); 640 return true; 641 } 642 return false; 643 } 644 645 /** 646 * Removes all components from this vector and sets its size to zero. 647 * 648 * <p>This method is identical in functionality to the {@link #clear} 649 * method (which is part of the {@link List} interface). 650 */ 651 public synchronized void removeAllElements() { 652 modCount++; 653 // Let gc do its work 654 for (int i = 0; i < elementCount; i++) 655 elementData[i] = null; 656 657 elementCount = 0; 658 } 659 660 /** 661 * Returns a clone of this vector. The copy will contain a 662 * reference to a clone of the internal data array, not a reference 663 * to the original internal data array of this {@code Vector} object. 664 * 665 * @return a clone of this vector 666 */ 667 public synchronized Object clone() { 668 try { 669 @SuppressWarnings("unchecked") 670 Vector<E> v = (Vector<E>) super.clone(); 671 v.elementData = Arrays.copyOf(elementData, elementCount); 672 v.modCount = 0; 673 return v; 674 } catch (CloneNotSupportedException e) { 675 // this shouldn't happen, since we are Cloneable 676 throw new InternalError(); 677 } 678 } 679 680 /** 681 * Returns an array containing all of the elements in this Vector 682 * in the correct order. 683 * 684 * @since 1.2 685 */ 686 public synchronized Object[] toArray() { 687 return Arrays.copyOf(elementData, elementCount); 688 } 689 690 /** 691 * Returns an array containing all of the elements in this Vector in the 692 * correct order; the runtime type of the returned array is that of the 693 * specified array. If the Vector fits in the specified array, it is 694 * returned therein. Otherwise, a new array is allocated with the runtime 695 * type of the specified array and the size of this Vector. 696 * 697 * <p>If the Vector fits in the specified array with room to spare 698 * (i.e., the array has more elements than the Vector), 699 * the element in the array immediately following the end of the 700 * Vector is set to null. (This is useful in determining the length 701 * of the Vector <em>only</em> if the caller knows that the Vector 702 * does not contain any null elements.) 703 * 704 * @param a the array into which the elements of the Vector are to 705 * be stored, if it is big enough; otherwise, a new array of the 706 * same runtime type is allocated for this purpose. 707 * @return an array containing the elements of the Vector 708 * @throws ArrayStoreException if the runtime type of a is not a supertype 709 * of the runtime type of every element in this Vector 710 * @throws NullPointerException if the given array is null 711 * @since 1.2 712 */ 713 @SuppressWarnings("unchecked") 714 public synchronized <T> T[] toArray(T[] a) { 715 if (a.length < elementCount) 716 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass()); 717 718 System.arraycopy(elementData, 0, a, 0, elementCount); 719 720 if (a.length > elementCount) 721 a[elementCount] = null; 722 723 return a; 724 } 725 726 // Positional Access Operations 727 728 @SuppressWarnings("unchecked") 729 E elementData(int index) { 730 return (E) elementData[index]; 731 } 732 733 /** 734 * Returns the element at the specified position in this Vector. 735 * 736 * @param index index of the element to return 737 * @return object at the specified index 738 * @throws ArrayIndexOutOfBoundsException if the index is out of range 739 * ({@code index < 0 || index >= size()}) 740 * @since 1.2 741 */ 742 public synchronized E get(int index) { 743 if (index >= elementCount) 744 throw new ArrayIndexOutOfBoundsException(index); 745 746 return elementData(index); 747 } 748 749 /** 750 * Replaces the element at the specified position in this Vector with the 751 * specified element. 752 * 753 * @param index index of the element to replace 754 * @param element element to be stored at the specified position 755 * @return the element previously at the specified position 756 * @throws ArrayIndexOutOfBoundsException if the index is out of range 757 * ({@code index < 0 || index >= size()}) 758 * @since 1.2 759 */ 760 public synchronized E set(int index, E element) { 761 if (index >= elementCount) 762 throw new ArrayIndexOutOfBoundsException(index); 763 764 E oldValue = elementData(index); 765 elementData[index] = element; 766 return oldValue; 767 } 768 769 /** 770 * Appends the specified element to the end of this Vector. 771 * 772 * @param e element to be appended to this Vector 773 * @return {@code true} (as specified by {@link Collection#add}) 774 * @since 1.2 775 */ 776 public synchronized boolean add(E e) { 777 modCount++; 778 ensureCapacityHelper(elementCount + 1); 779 elementData[elementCount++] = e; 780 return true; 781 } 782 783 /** 784 * Removes the first occurrence of the specified element in this Vector 785 * If the Vector does not contain the element, it is unchanged. More 786 * formally, removes the element with the lowest index i such that 787 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such 788 * an element exists). 789 * 790 * @param o element to be removed from this Vector, if present 791 * @return true if the Vector contained the specified element 792 * @since 1.2 793 */ 794 public boolean remove(Object o) { 795 return removeElement(o); 796 } 797 798 /** 799 * Inserts the specified element at the specified position in this Vector. 800 * Shifts the element currently at that position (if any) and any 801 * subsequent elements to the right (adds one to their indices). 802 * 803 * @param index index at which the specified element is to be inserted 804 * @param element element to be inserted 805 * @throws ArrayIndexOutOfBoundsException if the index is out of range 806 * ({@code index < 0 || index > size()}) 807 * @since 1.2 808 */ 809 public void add(int index, E element) { 810 insertElementAt(element, index); 811 } 812 813 /** 814 * Removes the element at the specified position in this Vector. 815 * Shifts any subsequent elements to the left (subtracts one from their 816 * indices). Returns the element that was removed from the Vector. 817 * 818 * @throws ArrayIndexOutOfBoundsException if the index is out of range 819 * ({@code index < 0 || index >= size()}) 820 * @param index the index of the element to be removed 821 * @return element that was removed 822 * @since 1.2 823 */ 824 public synchronized E remove(int index) { 825 modCount++; 826 if (index >= elementCount) 827 throw new ArrayIndexOutOfBoundsException(index); 828 E oldValue = elementData(index); 829 830 int numMoved = elementCount - index - 1; 831 if (numMoved > 0) 832 System.arraycopy(elementData, index+1, elementData, index, 833 numMoved); 834 elementData[--elementCount] = null; // Let gc do its work 835 836 return oldValue; 837 } 838 839 /** 840 * Removes all of the elements from this Vector. The Vector will 841 * be empty after this call returns (unless it throws an exception). 842 * 843 * @since 1.2 844 */ 845 public void clear() { 846 removeAllElements(); 847 } 848 849 // Bulk Operations 850 851 /** 852 * Returns true if this Vector contains all of the elements in the 853 * specified Collection. 854 * 855 * @param c a collection whose elements will be tested for containment 856 * in this Vector 857 * @return true if this Vector contains all of the elements in the 858 * specified collection 859 * @throws NullPointerException if the specified collection is null 860 */ 861 public synchronized boolean containsAll(Collection<?> c) { 862 return super.containsAll(c); 863 } 864 865 /** 866 * Appends all of the elements in the specified Collection to the end of 867 * this Vector, in the order that they are returned by the specified 868 * Collection's Iterator. The behavior of this operation is undefined if 869 * the specified Collection is modified while the operation is in progress. 870 * (This implies that the behavior of this call is undefined if the 871 * specified Collection is this Vector, and this Vector is nonempty.) 872 * 873 * @param c elements to be inserted into this Vector 874 * @return {@code true} if this Vector changed as a result of the call 875 * @throws NullPointerException if the specified collection is null 876 * @since 1.2 877 */ 878 public synchronized boolean addAll(Collection<? extends E> c) { 879 modCount++; 880 Object[] a = c.toArray(); 881 int numNew = a.length; 882 ensureCapacityHelper(elementCount + numNew); 883 System.arraycopy(a, 0, elementData, elementCount, numNew); 884 elementCount += numNew; 885 return numNew != 0; 886 } 887 888 /** 889 * Removes from this Vector all of its elements that are contained in the 890 * specified Collection. 891 * 892 * @param c a collection of elements to be removed from the Vector 893 * @return true if this Vector changed as a result of the call 894 * @throws ClassCastException if the types of one or more elements 895 * in this vector are incompatible with the specified 896 * collection (optional) 897 * @throws NullPointerException if this vector contains one or more null 898 * elements and the specified collection does not support null 899 * elements (optional), or if the specified collection is null 900 * @since 1.2 901 */ 902 public synchronized boolean removeAll(Collection<?> c) { 903 return super.removeAll(c); 904 } 905 906 /** 907 * Retains only the elements in this Vector that are contained in the 908 * specified Collection. In other words, removes from this Vector all 909 * of its elements that are not contained in the specified Collection. 910 * 911 * @param c a collection of elements to be retained in this Vector 912 * (all other elements are removed) 913 * @return true if this Vector changed as a result of the call 914 * @throws ClassCastException if the types of one or more elements 915 * in this vector are incompatible with the specified 916 * collection (optional) 917 * @throws NullPointerException if this vector contains one or more null 918 * elements and the specified collection does not support null 919 * elements (optional), or if the specified collection is null 920 * @since 1.2 921 */ 922 public synchronized boolean retainAll(Collection<?> c) { 923 return super.retainAll(c); 924 } 925 926 /** 927 * Inserts all of the elements in the specified Collection into this 928 * Vector at the specified position. Shifts the element currently at 929 * that position (if any) and any subsequent elements to the right 930 * (increases their indices). The new elements will appear in the Vector 931 * in the order that they are returned by the specified Collection's 932 * iterator. 933 * 934 * @param index index at which to insert the first element from the 935 * specified collection 936 * @param c elements to be inserted into this Vector 937 * @return {@code true} if this Vector changed as a result of the call 938 * @throws ArrayIndexOutOfBoundsException if the index is out of range 939 * ({@code index < 0 || index > size()}) 940 * @throws NullPointerException if the specified collection is null 941 * @since 1.2 942 */ 943 public synchronized boolean addAll(int index, Collection<? extends E> c) { 944 modCount++; 945 if (index < 0 || index > elementCount) 946 throw new ArrayIndexOutOfBoundsException(index); 947 948 Object[] a = c.toArray(); 949 int numNew = a.length; 950 ensureCapacityHelper(elementCount + numNew); 951 952 int numMoved = elementCount - index; 953 if (numMoved > 0) 954 System.arraycopy(elementData, index, elementData, index + numNew, 955 numMoved); 956 957 System.arraycopy(a, 0, elementData, index, numNew); 958 elementCount += numNew; 959 return numNew != 0; 960 } 961 962 /** 963 * Compares the specified Object with this Vector for equality. Returns 964 * true if and only if the specified Object is also a List, both Lists 965 * have the same size, and all corresponding pairs of elements in the two 966 * Lists are <em>equal</em>. (Two elements {@code e1} and 967 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null : 968 * e1.equals(e2))}.) In other words, two Lists are defined to be 969 * equal if they contain the same elements in the same order. 970 * 971 * @param o the Object to be compared for equality with this Vector 972 * @return true if the specified Object is equal to this Vector 973 */ 974 public synchronized boolean equals(Object o) { 975 return super.equals(o); 976 } 977 978 /** 979 * Returns the hash code value for this Vector. 980 */ 981 public synchronized int hashCode() { 982 return super.hashCode(); 983 } 984 985 /** 986 * Returns a string representation of this Vector, containing 987 * the String representation of each element. 988 */ 989 public synchronized String toString() { 990 return super.toString(); 991 } 992 993 /** 994 * Returns a view of the portion of this List between fromIndex, 995 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are 996 * equal, the returned List is empty.) The returned List is backed by this 997 * List, so changes in the returned List are reflected in this List, and 998 * vice-versa. The returned List supports all of the optional List 999 * operations supported by this List. 1000 * 1001 * <p>This method eliminates the need for explicit range operations (of 1002 * the sort that commonly exist for arrays). Any operation that expects 1003 * a List can be used as a range operation by operating on a subList view 1004 * instead of a whole List. For example, the following idiom 1005 * removes a range of elements from a List: 1006 * <pre> 1007 * list.subList(from, to).clear(); 1008 * </pre> 1009 * Similar idioms may be constructed for indexOf and lastIndexOf, 1010 * and all of the algorithms in the Collections class can be applied to 1011 * a subList. 1012 * 1013 * <p>The semantics of the List returned by this method become undefined if 1014 * the backing list (i.e., this List) is <i>structurally modified</i> in 1015 * any way other than via the returned List. (Structural modifications are 1016 * those that change the size of the List, or otherwise perturb it in such 1017 * a fashion that iterations in progress may yield incorrect results.) 1018 * 1019 * @param fromIndex low endpoint (inclusive) of the subList 1020 * @param toIndex high endpoint (exclusive) of the subList 1021 * @return a view of the specified range within this List 1022 * @throws IndexOutOfBoundsException if an endpoint index value is out of range 1023 * {@code (fromIndex < 0 || toIndex > size)} 1024 * @throws IllegalArgumentException if the endpoint indices are out of order 1025 * {@code (fromIndex > toIndex)} 1026 */ 1027 public synchronized List<E> subList(int fromIndex, int toIndex) { 1028 return Collections.synchronizedList(super.subList(fromIndex, toIndex), 1029 this); 1030 } 1031 1032 /** 1033 * Removes from this list all of the elements whose index is between 1034 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. 1035 * Shifts any succeeding elements to the left (reduces their index). 1036 * This call shortens the list by {@code (toIndex - fromIndex)} elements. 1037 * (If {@code toIndex==fromIndex}, this operation has no effect.) 1038 */ 1039 protected synchronized void removeRange(int fromIndex, int toIndex) { 1040 modCount++; 1041 int numMoved = elementCount - toIndex; 1042 System.arraycopy(elementData, toIndex, elementData, fromIndex, 1043 numMoved); 1044 1045 // Let gc do its work 1046 int newElementCount = elementCount - (toIndex-fromIndex); 1047 while (elementCount != newElementCount) 1048 elementData[--elementCount] = null; 1049 } 1050 1051 /** 1052 * Save the state of the {@code Vector} instance to a stream (that 1053 * is, serialize it). This method is present merely for synchronization. 1054 * It just calls the default writeObject method. 1055 */ 1056 private synchronized void writeObject(java.io.ObjectOutputStream s) 1057 throws java.io.IOException 1058 { 1059 s.defaultWriteObject(); 1060 } 1061 1062 /** 1063 * Returns a list iterator over the elements in this list (in proper 1064 * sequence), starting at the specified position in the list. 1065 * The specified index indicates the first element that would be 1066 * returned by an initial call to {@link ListIterator#next next}. 1067 * An initial call to {@link ListIterator#previous previous} would 1068 * return the element with the specified index minus one. 1069 * 1070 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1071 * 1072 * @throws IndexOutOfBoundsException {@inheritDoc} 1073 */ 1074 public synchronized ListIterator<E> listIterator(int index) { 1075 if (index < 0 || index > elementCount) 1076 throw new IndexOutOfBoundsException("Index: "+index); 1077 return new ListItr(index); 1078 } 1079 1080 /** 1081 * Returns a list iterator over the elements in this list (in proper 1082 * sequence). 1083 * 1084 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1085 * 1086 * @see #listIterator(int) 1087 */ 1088 public synchronized ListIterator<E> listIterator() { 1089 return new ListItr(0); 1090 } 1091 1092 /** 1093 * Returns an iterator over the elements in this list in proper sequence. 1094 * 1095 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1096 * 1097 * @return an iterator over the elements in this list in proper sequence 1098 */ 1099 public synchronized Iterator<E> iterator() { 1100 return new Itr(); 1101 } 1102 1103 /** 1104 * An optimized version of AbstractList.Itr 1105 */ 1106 private class Itr implements Iterator<E> { 1107 int cursor; // index of next element to return 1108 int lastRet = -1; // index of last element returned; -1 if no such 1109 int expectedModCount = modCount; 1110 1111 public boolean hasNext() { 1112 // Racy but within spec, since modifications are checked 1113 // within or after synchronization in next/previous 1114 return cursor != elementCount; 1115 } 1116 1117 public E next() { 1118 synchronized (Vector.this) { 1119 checkForComodification(); 1120 int i = cursor; 1121 if (i >= elementCount) 1122 throw new NoSuchElementException(); 1123 cursor = i + 1; 1124 return elementData(lastRet = i); 1125 } 1126 } 1127 1128 public void remove() { 1129 if (lastRet == -1) 1130 throw new IllegalStateException(); 1131 synchronized (Vector.this) { 1132 checkForComodification(); 1133 Vector.this.remove(lastRet); 1134 expectedModCount = modCount; 1135 } 1136 cursor = lastRet; 1137 lastRet = -1; 1138 } 1139 1140 final void checkForComodification() { 1141 if (modCount != expectedModCount) 1142 throw new ConcurrentModificationException(); 1143 } 1144 } 1145 1146 /** 1147 * An optimized version of AbstractList.ListItr 1148 */ 1149 final class ListItr extends Itr implements ListIterator<E> { 1150 ListItr(int index) { 1151 super(); 1152 cursor = index; 1153 } 1154 1155 public boolean hasPrevious() { 1156 return cursor != 0; 1157 } 1158 1159 public int nextIndex() { 1160 return cursor; 1161 } 1162 1163 public int previousIndex() { 1164 return cursor - 1; 1165 } 1166 1167 public E previous() { 1168 synchronized (Vector.this) { 1169 checkForComodification(); 1170 int i = cursor - 1; 1171 if (i < 0) 1172 throw new NoSuchElementException(); 1173 cursor = i; 1174 return elementData(lastRet = i); 1175 } 1176 } 1177 1178 public void set(E e) { 1179 if (lastRet == -1) 1180 throw new IllegalStateException(); 1181 synchronized (Vector.this) { 1182 checkForComodification(); 1183 Vector.this.set(lastRet, e); 1184 } 1185 } 1186 1187 public void add(E e) { 1188 int i = cursor; 1189 synchronized (Vector.this) { 1190 checkForComodification(); 1191 Vector.this.add(i, e); 1192 expectedModCount = modCount; 1193 } 1194 cursor = i + 1; 1195 lastRet = -1; 1196 } 1197 } 1198 }