Vector.java revision 5c35c7ebda68cc39b6bdee20f678a150336ebd1d
1/* 2 * Copyright (c) 1994, 2013, 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 26package java.util; 27 28import java.util.function.Consumer; 29import java.util.function.Predicate; 30 31/** 32 * The {@code Vector} class implements a growable array of 33 * objects. Like an array, it contains components that can be 34 * accessed using an integer index. However, the size of a 35 * {@code Vector} can grow or shrink as needed to accommodate 36 * adding and removing items after the {@code Vector} has been created. 37 * 38 * <p>Each vector tries to optimize storage management by maintaining a 39 * {@code capacity} and a {@code capacityIncrement}. The 40 * {@code capacity} is always at least as large as the vector 41 * size; it is usually larger because as components are added to the 42 * vector, the vector's storage increases in chunks the size of 43 * {@code capacityIncrement}. An application can increase the 44 * capacity of a vector before inserting a large number of 45 * components; this reduces the amount of incremental reallocation. 46 * 47 * <p><a name="fail-fast"> 48 * The iterators returned by this class's {@link #iterator() iterator} and 49 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em></a>: 50 * if the vector is structurally modified at any time after the iterator is 51 * created, in any way except through the iterator's own 52 * {@link ListIterator#remove() remove} or 53 * {@link ListIterator#add(Object) add} methods, the iterator will throw a 54 * {@link ConcurrentModificationException}. Thus, in the face of 55 * concurrent modification, the iterator fails quickly and cleanly, rather 56 * than risking arbitrary, non-deterministic behavior at an undetermined 57 * time in the future. The {@link Enumeration Enumerations} returned by 58 * the {@link #elements() elements} method are <em>not</em> fail-fast. 59 * 60 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed 61 * as it is, generally speaking, impossible to make any hard guarantees in the 62 * presence of unsynchronized concurrent modification. Fail-fast iterators 63 * throw {@code ConcurrentModificationException} on a best-effort basis. 64 * Therefore, it would be wrong to write a program that depended on this 65 * exception for its correctness: <i>the fail-fast behavior of iterators 66 * should be used only to detect bugs.</i> 67 * 68 * <p>As of the Java 2 platform v1.2, this class was retrofitted to 69 * implement the {@link List} interface, making it a member of the 70 * <a href="{@docRoot}/../technotes/guides/collections/index.html"> 71 * Java Collections Framework</a>. Unlike the new collection 72 * implementations, {@code Vector} is synchronized. If a thread-safe 73 * implementation is not needed, it is recommended to use {@link 74 * ArrayList} in place of {@code Vector}. 75 * 76 * @author Lee Boynton 77 * @author Jonathan Payne 78 * @see Collection 79 * @see LinkedList 80 * @since JDK1.0 81 */ 82public class Vector<E> 83 extends AbstractList<E> 84 implements List<E>, RandomAccess, Cloneable, java.io.Serializable 85{ 86 /** 87 * The array buffer into which the components of the vector are 88 * stored. The capacity of the vector is the length of this array buffer, 89 * and is at least large enough to contain all the vector's elements. 90 * 91 * <p>Any array elements following the last element in the Vector are null. 92 * 93 * @serial 94 */ 95 protected Object[] elementData; 96 97 /** 98 * The number of valid components in this {@code Vector} object. 99 * Components {@code elementData[0]} through 100 * {@code elementData[elementCount-1]} are the actual items. 101 * 102 * @serial 103 */ 104 protected int elementCount; 105 106 /** 107 * The amount by which the capacity of the vector is automatically 108 * incremented when its size becomes greater than its capacity. If 109 * the capacity increment is less than or equal to zero, the capacity 110 * of the vector is doubled each time it needs to grow. 111 * 112 * @serial 113 */ 114 protected int capacityIncrement; 115 116 /** use serialVersionUID from JDK 1.0.2 for interoperability */ 117 private static final long serialVersionUID = -2767605614048989439L; 118 119 /** 120 * Constructs an empty vector with the specified initial capacity and 121 * capacity increment. 122 * 123 * @param initialCapacity the initial capacity of the vector 124 * @param capacityIncrement the amount by which the capacity is 125 * increased when the vector overflows 126 * @throws IllegalArgumentException if the specified initial capacity 127 * is negative 128 */ 129 public Vector(int initialCapacity, int capacityIncrement) { 130 super(); 131 if (initialCapacity < 0) 132 throw new IllegalArgumentException("Illegal Capacity: "+ 133 initialCapacity); 134 this.elementData = new Object[initialCapacity]; 135 this.capacityIncrement = capacityIncrement; 136 } 137 138 /** 139 * Constructs an empty vector with the specified initial capacity and 140 * with its capacity increment equal to zero. 141 * 142 * @param initialCapacity the initial capacity of the vector 143 * @throws IllegalArgumentException if the specified initial capacity 144 * is negative 145 */ 146 public Vector(int initialCapacity) { 147 this(initialCapacity, 0); 148 } 149 150 /** 151 * Constructs an empty vector so that its internal data array 152 * has size {@code 10} and its standard capacity increment is 153 * zero. 154 */ 155 public Vector() { 156 this(10); 157 } 158 159 /** 160 * Constructs a vector containing the elements of the specified 161 * collection, in the order they are returned by the collection's 162 * iterator. 163 * 164 * @param c the collection whose elements are to be placed into this 165 * vector 166 * @throws NullPointerException if the specified collection is null 167 * @since 1.2 168 */ 169 public Vector(Collection<? extends E> c) { 170 elementData = c.toArray(); 171 elementCount = elementData.length; 172 // c.toArray might (incorrectly) not return Object[] (see 6260652) 173 if (elementData.getClass() != Object[].class) 174 elementData = Arrays.copyOf(elementData, elementCount, Object[].class); 175 } 176 177 /** 178 * Copies the components of this vector into the specified array. 179 * The item at index {@code k} in this vector is copied into 180 * component {@code k} of {@code anArray}. 181 * 182 * @param anArray the array into which the components get copied 183 * @throws NullPointerException if the given array is null 184 * @throws IndexOutOfBoundsException if the specified array is not 185 * large enough to hold all the components of this vector 186 * @throws ArrayStoreException if a component of this vector is not of 187 * a runtime type that can be stored in the specified array 188 * @see #toArray(Object[]) 189 */ 190 public synchronized void copyInto(Object[] anArray) { 191 System.arraycopy(elementData, 0, anArray, 0, elementCount); 192 } 193 194 /** 195 * Trims the capacity of this vector to be the vector's current 196 * size. If the capacity of this vector is larger than its current 197 * size, then the capacity is changed to equal the size by replacing 198 * its internal data array, kept in the field {@code elementData}, 199 * with a smaller one. An application can use this operation to 200 * minimize the storage of a vector. 201 */ 202 public synchronized void trimToSize() { 203 modCount++; 204 int oldCapacity = elementData.length; 205 if (elementCount < oldCapacity) { 206 elementData = Arrays.copyOf(elementData, elementCount); 207 } 208 } 209 210 /** 211 * Increases the capacity of this vector, if necessary, to ensure 212 * that it can hold at least the number of components specified by 213 * the minimum capacity argument. 214 * 215 * <p>If the current capacity of this vector is less than 216 * {@code minCapacity}, then its capacity is increased by replacing its 217 * internal data array, kept in the field {@code elementData}, with a 218 * larger one. The size of the new data array will be the old size plus 219 * {@code capacityIncrement}, unless the value of 220 * {@code capacityIncrement} is less than or equal to zero, in which case 221 * the new capacity will be twice the old capacity; but if this new size 222 * is still smaller than {@code minCapacity}, then the new capacity will 223 * be {@code minCapacity}. 224 * 225 * @param minCapacity the desired minimum capacity 226 */ 227 public synchronized void ensureCapacity(int minCapacity) { 228 if (minCapacity > 0) { 229 modCount++; 230 ensureCapacityHelper(minCapacity); 231 } 232 } 233 234 /** 235 * This implements the unsynchronized semantics of ensureCapacity. 236 * Synchronized methods in this class can internally call this 237 * method for ensuring capacity without incurring the cost of an 238 * extra synchronization. 239 * 240 * @see #ensureCapacity(int) 241 */ 242 private void ensureCapacityHelper(int minCapacity) { 243 // overflow-conscious code 244 if (minCapacity - elementData.length > 0) 245 grow(minCapacity); 246 } 247 248 /** 249 * The maximum size of array to allocate. 250 * Some VMs reserve some header words in an array. 251 * Attempts to allocate larger arrays may result in 252 * OutOfMemoryError: Requested array size exceeds VM limit 253 */ 254 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8; 255 256 private void grow(int minCapacity) { 257 // overflow-conscious code 258 int oldCapacity = elementData.length; 259 int newCapacity = oldCapacity + ((capacityIncrement > 0) ? 260 capacityIncrement : oldCapacity); 261 if (newCapacity - minCapacity < 0) 262 newCapacity = minCapacity; 263 if (newCapacity - MAX_ARRAY_SIZE > 0) 264 newCapacity = hugeCapacity(minCapacity); 265 elementData = Arrays.copyOf(elementData, newCapacity); 266 } 267 268 private static int hugeCapacity(int minCapacity) { 269 if (minCapacity < 0) // overflow 270 throw new OutOfMemoryError(); 271 return (minCapacity > MAX_ARRAY_SIZE) ? 272 Integer.MAX_VALUE : 273 MAX_ARRAY_SIZE; 274 } 275 276 /** 277 * Sets the size of this vector. If the new size is greater than the 278 * current size, new {@code null} items are added to the end of 279 * the vector. If the new size is less than the current size, all 280 * components at index {@code newSize} and greater are discarded. 281 * 282 * @param newSize the new size of this vector 283 * @throws ArrayIndexOutOfBoundsException if the new size is negative 284 */ 285 public synchronized void setSize(int newSize) { 286 modCount++; 287 if (newSize > elementCount) { 288 ensureCapacityHelper(newSize); 289 } else { 290 for (int i = newSize ; i < elementCount ; i++) { 291 elementData[i] = null; 292 } 293 } 294 elementCount = newSize; 295 } 296 297 /** 298 * Returns the current capacity of this vector. 299 * 300 * @return the current capacity (the length of its internal 301 * data array, kept in the field {@code elementData} 302 * of this vector) 303 */ 304 public synchronized int capacity() { 305 return elementData.length; 306 } 307 308 /** 309 * Returns the number of components in this vector. 310 * 311 * @return the number of components in this vector 312 */ 313 public synchronized int size() { 314 return elementCount; 315 } 316 317 /** 318 * Tests if this vector has no components. 319 * 320 * @return {@code true} if and only if this vector has 321 * no components, that is, its size is zero; 322 * {@code false} otherwise. 323 */ 324 public synchronized boolean isEmpty() { 325 return elementCount == 0; 326 } 327 328 /** 329 * Returns an enumeration of the components of this vector. The 330 * returned {@code Enumeration} object will generate all items in 331 * this vector. The first item generated is the item at index {@code 0}, 332 * then the item at index {@code 1}, and so on. 333 * 334 * @return an enumeration of the components of this vector 335 * @see Iterator 336 */ 337 public Enumeration<E> elements() { 338 return new Enumeration<E>() { 339 int count = 0; 340 341 public boolean hasMoreElements() { 342 return count < elementCount; 343 } 344 345 public E nextElement() { 346 synchronized (Vector.this) { 347 if (count < elementCount) { 348 return elementData(count++); 349 } 350 } 351 throw new NoSuchElementException("Vector Enumeration"); 352 } 353 }; 354 } 355 356 /** 357 * Returns {@code true} if this vector contains the specified element. 358 * More formally, returns {@code true} if and only if this vector 359 * contains at least one element {@code e} such that 360 * <tt>(o==null ? e==null : o.equals(e))</tt>. 361 * 362 * @param o element whose presence in this vector is to be tested 363 * @return {@code true} if this vector contains the specified element 364 */ 365 public boolean contains(Object o) { 366 return indexOf(o, 0) >= 0; 367 } 368 369 /** 370 * Returns the index of the first occurrence of the specified element 371 * in this vector, or -1 if this vector does not contain the element. 372 * More formally, returns the lowest index {@code i} such that 373 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, 374 * or -1 if there is no such index. 375 * 376 * @param o element to search for 377 * @return the index of the first occurrence of the specified element in 378 * this vector, or -1 if this vector does not contain the element 379 */ 380 public int indexOf(Object o) { 381 return indexOf(o, 0); 382 } 383 384 /** 385 * Returns the index of the first occurrence of the specified element in 386 * this vector, searching forwards from {@code index}, or returns -1 if 387 * the element is not found. 388 * More formally, returns the lowest index {@code i} such that 389 * <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>, 390 * or -1 if there is no such index. 391 * 392 * @param o element to search for 393 * @param index index to start searching from 394 * @return the index of the first occurrence of the element in 395 * this vector at position {@code index} or later in the vector; 396 * {@code -1} if the element is not found. 397 * @throws IndexOutOfBoundsException if the specified index is negative 398 * @see Object#equals(Object) 399 */ 400 public synchronized int indexOf(Object o, int index) { 401 if (o == null) { 402 for (int i = index ; i < elementCount ; i++) 403 if (elementData[i]==null) 404 return i; 405 } else { 406 for (int i = index ; i < elementCount ; i++) 407 if (o.equals(elementData[i])) 408 return i; 409 } 410 return -1; 411 } 412 413 /** 414 * Returns the index of the last occurrence of the specified element 415 * in this vector, or -1 if this vector does not contain the element. 416 * More formally, returns the highest index {@code i} such that 417 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, 418 * or -1 if there is no such index. 419 * 420 * @param o element to search for 421 * @return the index of the last occurrence of the specified element in 422 * this vector, or -1 if this vector does not contain the element 423 */ 424 public synchronized int lastIndexOf(Object o) { 425 return lastIndexOf(o, elementCount-1); 426 } 427 428 /** 429 * Returns the index of the last occurrence of the specified element in 430 * this vector, searching backwards from {@code index}, or returns -1 if 431 * the element is not found. 432 * More formally, returns the highest index {@code i} such that 433 * <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>, 434 * or -1 if there is no such index. 435 * 436 * @param o element to search for 437 * @param index index to start searching backwards from 438 * @return the index of the last occurrence of the element at position 439 * less than or equal to {@code index} in this vector; 440 * -1 if the element is not found. 441 * @throws IndexOutOfBoundsException if the specified index is greater 442 * than or equal to the current size of this vector 443 */ 444 public synchronized int lastIndexOf(Object o, int index) { 445 if (index >= elementCount) 446 throw new IndexOutOfBoundsException(index + " >= "+ elementCount); 447 448 if (o == null) { 449 for (int i = index; i >= 0; i--) 450 if (elementData[i]==null) 451 return i; 452 } else { 453 for (int i = index; i >= 0; i--) 454 if (o.equals(elementData[i])) 455 return i; 456 } 457 return -1; 458 } 459 460 /** 461 * Returns the component at the specified index. 462 * 463 * <p>This method is identical in functionality to the {@link #get(int)} 464 * method (which is part of the {@link List} interface). 465 * 466 * @param index an index into this vector 467 * @return the component at the specified index 468 * @throws ArrayIndexOutOfBoundsException if the index is out of range 469 * ({@code index < 0 || index >= size()}) 470 */ 471 public synchronized E elementAt(int index) { 472 if (index >= elementCount) { 473 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount); 474 } 475 476 return elementData(index); 477 } 478 479 /** 480 * Returns the first component (the item at index {@code 0}) of 481 * this vector. 482 * 483 * @return the first component of this vector 484 * @throws NoSuchElementException if this vector has no components 485 */ 486 public synchronized E firstElement() { 487 if (elementCount == 0) { 488 throw new NoSuchElementException(); 489 } 490 return elementData(0); 491 } 492 493 /** 494 * Returns the last component of the vector. 495 * 496 * @return the last component of the vector, i.e., the component at index 497 * <code>size() - 1</code>. 498 * @throws NoSuchElementException if this vector is empty 499 */ 500 public synchronized E lastElement() { 501 if (elementCount == 0) { 502 throw new NoSuchElementException(); 503 } 504 return elementData(elementCount - 1); 505 } 506 507 /** 508 * Sets the component at the specified {@code index} of this 509 * vector to be the specified object. The previous component at that 510 * position is discarded. 511 * 512 * <p>The index must be a value greater than or equal to {@code 0} 513 * and less than the current size of the vector. 514 * 515 * <p>This method is identical in functionality to the 516 * {@link #set(int, Object) set(int, E)} 517 * method (which is part of the {@link List} interface). Note that the 518 * {@code set} method reverses the order of the parameters, to more closely 519 * match array usage. Note also that the {@code set} method returns the 520 * old value that was stored at the specified position. 521 * 522 * @param obj what the component is to be set to 523 * @param index the specified index 524 * @throws ArrayIndexOutOfBoundsException if the index is out of range 525 * ({@code index < 0 || index >= size()}) 526 */ 527 public synchronized void setElementAt(E obj, int index) { 528 if (index >= elementCount) { 529 throw new ArrayIndexOutOfBoundsException(index + " >= " + 530 elementCount); 531 } 532 elementData[index] = obj; 533 } 534 535 /** 536 * Deletes the component at the specified index. Each component in 537 * this vector with an index greater or equal to the specified 538 * {@code index} is shifted downward to have an index one 539 * smaller than the value it had previously. The size of this vector 540 * is decreased by {@code 1}. 541 * 542 * <p>The index must be a value greater than or equal to {@code 0} 543 * and less than the current size of the vector. 544 * 545 * <p>This method is identical in functionality to the {@link #remove(int)} 546 * method (which is part of the {@link List} interface). Note that the 547 * {@code remove} method returns the old value that was stored at the 548 * specified position. 549 * 550 * @param index the index of the object to remove 551 * @throws ArrayIndexOutOfBoundsException if the index is out of range 552 * ({@code index < 0 || index >= size()}) 553 */ 554 public synchronized void removeElementAt(int index) { 555 modCount++; 556 if (index >= elementCount) { 557 throw new ArrayIndexOutOfBoundsException(index + " >= " + 558 elementCount); 559 } 560 else if (index < 0) { 561 throw new ArrayIndexOutOfBoundsException(index); 562 } 563 int j = elementCount - index - 1; 564 if (j > 0) { 565 System.arraycopy(elementData, index + 1, elementData, index, j); 566 } 567 elementCount--; 568 elementData[elementCount] = null; /* to let gc do its work */ 569 } 570 571 /** 572 * Inserts the specified object as a component in this vector at the 573 * specified {@code index}. Each component in this vector with 574 * an index greater or equal to the specified {@code index} is 575 * shifted upward to have an index one greater than the value it had 576 * previously. 577 * 578 * <p>The index must be a value greater than or equal to {@code 0} 579 * and less than or equal to the current size of the vector. (If the 580 * index is equal to the current size of the vector, the new element 581 * is appended to the Vector.) 582 * 583 * <p>This method is identical in functionality to the 584 * {@link #add(int, Object) add(int, E)} 585 * method (which is part of the {@link List} interface). Note that the 586 * {@code add} method reverses the order of the parameters, to more closely 587 * match array usage. 588 * 589 * @param obj the component to insert 590 * @param index where to insert the new component 591 * @throws ArrayIndexOutOfBoundsException if the index is out of range 592 * ({@code index < 0 || index > size()}) 593 */ 594 public synchronized void insertElementAt(E obj, int index) { 595 modCount++; 596 if (index > elementCount) { 597 throw new ArrayIndexOutOfBoundsException(index 598 + " > " + elementCount); 599 } 600 ensureCapacityHelper(elementCount + 1); 601 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index); 602 elementData[index] = obj; 603 elementCount++; 604 } 605 606 /** 607 * Adds the specified component to the end of this vector, 608 * increasing its size by one. The capacity of this vector is 609 * increased if its size becomes greater than its capacity. 610 * 611 * <p>This method is identical in functionality to the 612 * {@link #add(Object) add(E)} 613 * method (which is part of the {@link List} interface). 614 * 615 * @param obj the component to be added 616 */ 617 public synchronized void addElement(E obj) { 618 modCount++; 619 ensureCapacityHelper(elementCount + 1); 620 elementData[elementCount++] = obj; 621 } 622 623 /** 624 * Removes the first (lowest-indexed) occurrence of the argument 625 * from this vector. If the object is found in this vector, each 626 * component in the vector with an index greater or equal to the 627 * object's index is shifted downward to have an index one smaller 628 * than the value it had previously. 629 * 630 * <p>This method is identical in functionality to the 631 * {@link #remove(Object)} method (which is part of the 632 * {@link List} interface). 633 * 634 * @param obj the component to be removed 635 * @return {@code true} if the argument was a component of this 636 * vector; {@code false} otherwise. 637 */ 638 public synchronized boolean removeElement(Object obj) { 639 modCount++; 640 int i = indexOf(obj); 641 if (i >= 0) { 642 removeElementAt(i); 643 return true; 644 } 645 return false; 646 } 647 648 /** 649 * Removes all components from this vector and sets its size to zero. 650 * 651 * <p>This method is identical in functionality to the {@link #clear} 652 * method (which is part of the {@link List} interface). 653 */ 654 public synchronized void removeAllElements() { 655 modCount++; 656 // Let gc do its work 657 for (int i = 0; i < elementCount; i++) 658 elementData[i] = null; 659 660 elementCount = 0; 661 } 662 663 /** 664 * Returns a clone of this vector. The copy will contain a 665 * reference to a clone of the internal data array, not a reference 666 * to the original internal data array of this {@code Vector} object. 667 * 668 * @return a clone of this vector 669 */ 670 public synchronized Object clone() { 671 try { 672 @SuppressWarnings("unchecked") 673 Vector<E> v = (Vector<E>) super.clone(); 674 v.elementData = Arrays.copyOf(elementData, elementCount); 675 v.modCount = 0; 676 return v; 677 } catch (CloneNotSupportedException e) { 678 // this shouldn't happen, since we are Cloneable 679 throw new InternalError(e); 680 } 681 } 682 683 /** 684 * Returns an array containing all of the elements in this Vector 685 * in the correct order. 686 * 687 * @since 1.2 688 */ 689 public synchronized Object[] toArray() { 690 return Arrays.copyOf(elementData, elementCount); 691 } 692 693 /** 694 * Returns an array containing all of the elements in this Vector in the 695 * correct order; the runtime type of the returned array is that of the 696 * specified array. If the Vector fits in the specified array, it is 697 * returned therein. Otherwise, a new array is allocated with the runtime 698 * type of the specified array and the size of this Vector. 699 * 700 * <p>If the Vector fits in the specified array with room to spare 701 * (i.e., the array has more elements than the Vector), 702 * the element in the array immediately following the end of the 703 * Vector is set to null. (This is useful in determining the length 704 * of the Vector <em>only</em> if the caller knows that the Vector 705 * does not contain any null elements.) 706 * 707 * @param a the array into which the elements of the Vector are to 708 * be stored, if it is big enough; otherwise, a new array of the 709 * same runtime type is allocated for this purpose. 710 * @return an array containing the elements of the Vector 711 * @throws ArrayStoreException if the runtime type of a is not a supertype 712 * of the runtime type of every element in this Vector 713 * @throws NullPointerException if the given array is null 714 * @since 1.2 715 */ 716 @SuppressWarnings("unchecked") 717 public synchronized <T> T[] toArray(T[] a) { 718 if (a.length < elementCount) 719 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass()); 720 721 System.arraycopy(elementData, 0, a, 0, elementCount); 722 723 if (a.length > elementCount) 724 a[elementCount] = null; 725 726 return a; 727 } 728 729 // Positional Access Operations 730 731 @SuppressWarnings("unchecked") 732 E elementData(int index) { 733 return (E) elementData[index]; 734 } 735 736 /** 737 * Returns the element at the specified position in this Vector. 738 * 739 * @param index index of the element to return 740 * @return object at the specified index 741 * @throws ArrayIndexOutOfBoundsException if the index is out of range 742 * ({@code index < 0 || index >= size()}) 743 * @since 1.2 744 */ 745 public synchronized E get(int index) { 746 if (index >= elementCount) 747 throw new ArrayIndexOutOfBoundsException(index); 748 749 return elementData(index); 750 } 751 752 /** 753 * Replaces the element at the specified position in this Vector with the 754 * specified element. 755 * 756 * @param index index of the element to replace 757 * @param element element to be stored at the specified position 758 * @return the element previously at the specified position 759 * @throws ArrayIndexOutOfBoundsException if the index is out of range 760 * ({@code index < 0 || index >= size()}) 761 * @since 1.2 762 */ 763 public synchronized E set(int index, E element) { 764 if (index >= elementCount) 765 throw new ArrayIndexOutOfBoundsException(index); 766 767 E oldValue = elementData(index); 768 elementData[index] = element; 769 return oldValue; 770 } 771 772 /** 773 * Appends the specified element to the end of this Vector. 774 * 775 * @param e element to be appended to this Vector 776 * @return {@code true} (as specified by {@link Collection#add}) 777 * @since 1.2 778 */ 779 public synchronized boolean add(E e) { 780 modCount++; 781 ensureCapacityHelper(elementCount + 1); 782 elementData[elementCount++] = e; 783 return true; 784 } 785 786 /** 787 * Removes the first occurrence of the specified element in this Vector 788 * If the Vector does not contain the element, it is unchanged. More 789 * formally, removes the element with the lowest index i such that 790 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such 791 * an element exists). 792 * 793 * @param o element to be removed from this Vector, if present 794 * @return true if the Vector contained the specified element 795 * @since 1.2 796 */ 797 public boolean remove(Object o) { 798 return removeElement(o); 799 } 800 801 /** 802 * Inserts the specified element at the specified position in this Vector. 803 * Shifts the element currently at that position (if any) and any 804 * subsequent elements to the right (adds one to their indices). 805 * 806 * @param index index at which the specified element is to be inserted 807 * @param element element to be inserted 808 * @throws ArrayIndexOutOfBoundsException if the index is out of range 809 * ({@code index < 0 || index > size()}) 810 * @since 1.2 811 */ 812 public void add(int index, E element) { 813 insertElementAt(element, index); 814 } 815 816 /** 817 * Removes the element at the specified position in this Vector. 818 * Shifts any subsequent elements to the left (subtracts one from their 819 * indices). Returns the element that was removed from the Vector. 820 * 821 * @throws ArrayIndexOutOfBoundsException if the index is out of range 822 * ({@code index < 0 || index >= size()}) 823 * @param index the index of the element to be removed 824 * @return element that was removed 825 * @since 1.2 826 */ 827 public synchronized E remove(int index) { 828 modCount++; 829 if (index >= elementCount) 830 throw new ArrayIndexOutOfBoundsException(index); 831 E oldValue = elementData(index); 832 833 int numMoved = elementCount - index - 1; 834 if (numMoved > 0) 835 System.arraycopy(elementData, index+1, elementData, index, 836 numMoved); 837 elementData[--elementCount] = null; // Let gc do its work 838 839 return oldValue; 840 } 841 842 /** 843 * Removes all of the elements from this Vector. The Vector will 844 * be empty after this call returns (unless it throws an exception). 845 * 846 * @since 1.2 847 */ 848 public void clear() { 849 removeAllElements(); 850 } 851 852 // Bulk Operations 853 854 /** 855 * Returns true if this Vector contains all of the elements in the 856 * specified Collection. 857 * 858 * @param c a collection whose elements will be tested for containment 859 * in this Vector 860 * @return true if this Vector contains all of the elements in the 861 * specified collection 862 * @throws NullPointerException if the specified collection is null 863 */ 864 public synchronized boolean containsAll(Collection<?> c) { 865 return super.containsAll(c); 866 } 867 868 /** 869 * Appends all of the elements in the specified Collection to the end of 870 * this Vector, in the order that they are returned by the specified 871 * Collection's Iterator. The behavior of this operation is undefined if 872 * the specified Collection is modified while the operation is in progress. 873 * (This implies that the behavior of this call is undefined if the 874 * specified Collection is this Vector, and this Vector is nonempty.) 875 * 876 * @param c elements to be inserted into this Vector 877 * @return {@code true} if this Vector changed as a result of the call 878 * @throws NullPointerException if the specified collection is null 879 * @since 1.2 880 */ 881 public synchronized boolean addAll(Collection<? extends E> c) { 882 modCount++; 883 Object[] a = c.toArray(); 884 int numNew = a.length; 885 ensureCapacityHelper(elementCount + numNew); 886 System.arraycopy(a, 0, elementData, elementCount, numNew); 887 elementCount += numNew; 888 return numNew != 0; 889 } 890 891 /** 892 * Removes from this Vector all of its elements that are contained in the 893 * specified Collection. 894 * 895 * @param c a collection of elements to be removed from the Vector 896 * @return true if this Vector changed as a result of the call 897 * @throws ClassCastException if the types of one or more elements 898 * in this vector are incompatible with the specified 899 * collection 900 * (<a href="Collection.html#optional-restrictions">optional</a>) 901 * @throws NullPointerException if this vector contains one or more null 902 * elements and the specified collection does not support null 903 * elements 904 * (<a href="Collection.html#optional-restrictions">optional</a>), 905 * or if the specified collection is null 906 * @since 1.2 907 */ 908 public synchronized boolean removeAll(Collection<?> c) { 909 return super.removeAll(c); 910 } 911 912 /** 913 * Retains only the elements in this Vector that are contained in the 914 * specified Collection. In other words, removes from this Vector all 915 * of its elements that are not contained in the specified Collection. 916 * 917 * @param c a collection of elements to be retained in this Vector 918 * (all other elements are removed) 919 * @return true if this Vector changed as a result of the call 920 * @throws ClassCastException if the types of one or more elements 921 * in this vector are incompatible with the specified 922 * collection 923 * (<a href="Collection.html#optional-restrictions">optional</a>) 924 * @throws NullPointerException if this vector contains one or more null 925 * elements and the specified collection does not support null 926 * elements 927 * (<a href="Collection.html#optional-restrictions">optional</a>), 928 * or if the specified collection is null 929 * @since 1.2 930 */ 931 public synchronized boolean retainAll(Collection<?> c) { 932 return super.retainAll(c); 933 } 934 935 /** 936 * Inserts all of the elements in the specified Collection into this 937 * Vector at the specified position. Shifts the element currently at 938 * that position (if any) and any subsequent elements to the right 939 * (increases their indices). The new elements will appear in the Vector 940 * in the order that they are returned by the specified Collection's 941 * iterator. 942 * 943 * @param index index at which to insert the first element from the 944 * specified collection 945 * @param c elements to be inserted into this Vector 946 * @return {@code true} if this Vector changed as a result of the call 947 * @throws ArrayIndexOutOfBoundsException if the index is out of range 948 * ({@code index < 0 || index > size()}) 949 * @throws NullPointerException if the specified collection is null 950 * @since 1.2 951 */ 952 public synchronized boolean addAll(int index, Collection<? extends E> c) { 953 modCount++; 954 if (index < 0 || index > elementCount) 955 throw new ArrayIndexOutOfBoundsException(index); 956 957 Object[] a = c.toArray(); 958 int numNew = a.length; 959 ensureCapacityHelper(elementCount + numNew); 960 961 int numMoved = elementCount - index; 962 if (numMoved > 0) 963 System.arraycopy(elementData, index, elementData, index + numNew, 964 numMoved); 965 966 System.arraycopy(a, 0, elementData, index, numNew); 967 elementCount += numNew; 968 return numNew != 0; 969 } 970 971 /** 972 * Compares the specified Object with this Vector for equality. Returns 973 * true if and only if the specified Object is also a List, both Lists 974 * have the same size, and all corresponding pairs of elements in the two 975 * Lists are <em>equal</em>. (Two elements {@code e1} and 976 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null : 977 * e1.equals(e2))}.) In other words, two Lists are defined to be 978 * equal if they contain the same elements in the same order. 979 * 980 * @param o the Object to be compared for equality with this Vector 981 * @return true if the specified Object is equal to this Vector 982 */ 983 public synchronized boolean equals(Object o) { 984 return super.equals(o); 985 } 986 987 /** 988 * Returns the hash code value for this Vector. 989 */ 990 public synchronized int hashCode() { 991 return super.hashCode(); 992 } 993 994 /** 995 * Returns a string representation of this Vector, containing 996 * the String representation of each element. 997 */ 998 public synchronized String toString() { 999 return super.toString(); 1000 } 1001 1002 /** 1003 * Returns a view of the portion of this List between fromIndex, 1004 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are 1005 * equal, the returned List is empty.) The returned List is backed by this 1006 * List, so changes in the returned List are reflected in this List, and 1007 * vice-versa. The returned List supports all of the optional List 1008 * operations supported by this List. 1009 * 1010 * <p>This method eliminates the need for explicit range operations (of 1011 * the sort that commonly exist for arrays). Any operation that expects 1012 * a List can be used as a range operation by operating on a subList view 1013 * instead of a whole List. For example, the following idiom 1014 * removes a range of elements from a List: 1015 * <pre> 1016 * list.subList(from, to).clear(); 1017 * </pre> 1018 * Similar idioms may be constructed for indexOf and lastIndexOf, 1019 * and all of the algorithms in the Collections class can be applied to 1020 * a subList. 1021 * 1022 * <p>The semantics of the List returned by this method become undefined if 1023 * the backing list (i.e., this List) is <i>structurally modified</i> in 1024 * any way other than via the returned List. (Structural modifications are 1025 * those that change the size of the List, or otherwise perturb it in such 1026 * a fashion that iterations in progress may yield incorrect results.) 1027 * 1028 * @param fromIndex low endpoint (inclusive) of the subList 1029 * @param toIndex high endpoint (exclusive) of the subList 1030 * @return a view of the specified range within this List 1031 * @throws IndexOutOfBoundsException if an endpoint index value is out of range 1032 * {@code (fromIndex < 0 || toIndex > size)} 1033 * @throws IllegalArgumentException if the endpoint indices are out of order 1034 * {@code (fromIndex > toIndex)} 1035 */ 1036 public synchronized List<E> subList(int fromIndex, int toIndex) { 1037 return Collections.synchronizedList(super.subList(fromIndex, toIndex), 1038 this); 1039 } 1040 1041 /** 1042 * Removes from this list all of the elements whose index is between 1043 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive. 1044 * Shifts any succeeding elements to the left (reduces their index). 1045 * This call shortens the list by {@code (toIndex - fromIndex)} elements. 1046 * (If {@code toIndex==fromIndex}, this operation has no effect.) 1047 */ 1048 protected synchronized void removeRange(int fromIndex, int toIndex) { 1049 modCount++; 1050 int numMoved = elementCount - toIndex; 1051 System.arraycopy(elementData, toIndex, elementData, fromIndex, 1052 numMoved); 1053 1054 // Let gc do its work 1055 int newElementCount = elementCount - (toIndex-fromIndex); 1056 while (elementCount != newElementCount) 1057 elementData[--elementCount] = null; 1058 } 1059 1060 /** 1061 * Save the state of the {@code Vector} instance to a stream (that 1062 * is, serialize it). 1063 * This method performs synchronization to ensure the consistency 1064 * of the serialized data. 1065 */ 1066 private void writeObject(java.io.ObjectOutputStream s) 1067 throws java.io.IOException { 1068 final java.io.ObjectOutputStream.PutField fields = s.putFields(); 1069 final Object[] data; 1070 synchronized (this) { 1071 fields.put("capacityIncrement", capacityIncrement); 1072 fields.put("elementCount", elementCount); 1073 data = elementData.clone(); 1074 } 1075 fields.put("elementData", data); 1076 s.writeFields(); 1077 } 1078 1079 /** 1080 * Returns a list iterator over the elements in this list (in proper 1081 * sequence), starting at the specified position in the list. 1082 * The specified index indicates the first element that would be 1083 * returned by an initial call to {@link ListIterator#next next}. 1084 * An initial call to {@link ListIterator#previous previous} would 1085 * return the element with the specified index minus one. 1086 * 1087 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1088 * 1089 * @throws IndexOutOfBoundsException {@inheritDoc} 1090 */ 1091 public synchronized ListIterator<E> listIterator(int index) { 1092 if (index < 0 || index > elementCount) 1093 throw new IndexOutOfBoundsException("Index: "+index); 1094 return new ListItr(index); 1095 } 1096 1097 /** 1098 * Returns a list iterator over the elements in this list (in proper 1099 * sequence). 1100 * 1101 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1102 * 1103 * @see #listIterator(int) 1104 */ 1105 public synchronized ListIterator<E> listIterator() { 1106 return new ListItr(0); 1107 } 1108 1109 /** 1110 * Returns an iterator over the elements in this list in proper sequence. 1111 * 1112 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>. 1113 * 1114 * @return an iterator over the elements in this list in proper sequence 1115 */ 1116 public synchronized Iterator<E> iterator() { 1117 return new Itr(); 1118 } 1119 1120 /** 1121 * An optimized version of AbstractList.Itr 1122 */ 1123 private class Itr implements Iterator<E> { 1124 int cursor; // index of next element to return 1125 int lastRet = -1; // index of last element returned; -1 if no such 1126 int expectedModCount = modCount; 1127 1128 public boolean hasNext() { 1129 // Racy but within spec, since modifications are checked 1130 // within or after synchronization in next/previous 1131 return cursor != elementCount; 1132 } 1133 1134 public E next() { 1135 synchronized (Vector.this) { 1136 checkForComodification(); 1137 int i = cursor; 1138 if (i >= elementCount) 1139 throw new NoSuchElementException(); 1140 cursor = i + 1; 1141 return elementData(lastRet = i); 1142 } 1143 } 1144 1145 public void remove() { 1146 if (lastRet == -1) 1147 throw new IllegalStateException(); 1148 synchronized (Vector.this) { 1149 checkForComodification(); 1150 Vector.this.remove(lastRet); 1151 expectedModCount = modCount; 1152 } 1153 cursor = lastRet; 1154 lastRet = -1; 1155 } 1156 1157 @Override 1158 public void forEachRemaining(Consumer<? super E> action) { 1159 Objects.requireNonNull(action); 1160 synchronized (Vector.this) { 1161 final int size = elementCount; 1162 int i = cursor; 1163 if (i >= size) { 1164 return; 1165 } 1166 @SuppressWarnings("unchecked") 1167 final E[] elementData = (E[]) Vector.this.elementData; 1168 if (i >= elementData.length) { 1169 throw new ConcurrentModificationException(); 1170 } 1171 while (i != size && modCount == expectedModCount) { 1172 action.accept(elementData[i++]); 1173 } 1174 // update once at end of iteration to reduce heap write traffic 1175 cursor = i; 1176 lastRet = i - 1; 1177 checkForComodification(); 1178 } 1179 } 1180 1181 final void checkForComodification() { 1182 if (modCount != expectedModCount) 1183 throw new ConcurrentModificationException(); 1184 } 1185 } 1186 1187 /** 1188 * An optimized version of AbstractList.ListItr 1189 */ 1190 final class ListItr extends Itr implements ListIterator<E> { 1191 ListItr(int index) { 1192 super(); 1193 cursor = index; 1194 } 1195 1196 public boolean hasPrevious() { 1197 return cursor != 0; 1198 } 1199 1200 public int nextIndex() { 1201 return cursor; 1202 } 1203 1204 public int previousIndex() { 1205 return cursor - 1; 1206 } 1207 1208 public E previous() { 1209 synchronized (Vector.this) { 1210 checkForComodification(); 1211 int i = cursor - 1; 1212 if (i < 0) 1213 throw new NoSuchElementException(); 1214 cursor = i; 1215 return elementData(lastRet = i); 1216 } 1217 } 1218 1219 public void set(E e) { 1220 if (lastRet == -1) 1221 throw new IllegalStateException(); 1222 synchronized (Vector.this) { 1223 checkForComodification(); 1224 Vector.this.set(lastRet, e); 1225 } 1226 } 1227 1228 public void add(E e) { 1229 int i = cursor; 1230 synchronized (Vector.this) { 1231 checkForComodification(); 1232 Vector.this.add(i, e); 1233 expectedModCount = modCount; 1234 } 1235 cursor = i + 1; 1236 lastRet = -1; 1237 } 1238 } 1239 1240 @Override 1241 public synchronized void forEach(Consumer<? super E> action) { 1242 Objects.requireNonNull(action); 1243 final int expectedModCount = modCount; 1244 @SuppressWarnings("unchecked") 1245 final E[] elementData = (E[]) this.elementData; 1246 final int elementCount = this.elementCount; 1247 for (int i=0; modCount == expectedModCount && i < elementCount; i++) { 1248 action.accept(elementData[i]); 1249 } 1250 if (modCount != expectedModCount) { 1251 throw new ConcurrentModificationException(); 1252 } 1253 } 1254 1255 /** 1256 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em> 1257 * and <em>fail-fast</em> {@link Spliterator} over the elements in this 1258 * list. 1259 * 1260 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED}, 1261 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}. 1262 * Overriding implementations should document the reporting of additional 1263 * characteristic values. 1264 * 1265 * @return a {@code Spliterator} over the elements in this list 1266 * @since 1.8 1267 */ 1268 @Override 1269 public Spliterator<E> spliterator() { 1270 return new VectorSpliterator<>(this, null, 0, -1, 0); 1271 } 1272 1273 /** Similar to ArrayList Spliterator */ 1274 static final class VectorSpliterator<E> implements Spliterator<E> { 1275 private final Vector<E> list; 1276 private Object[] array; 1277 private int index; // current index, modified on advance/split 1278 private int fence; // -1 until used; then one past last index 1279 private int expectedModCount; // initialized when fence set 1280 1281 /** Create new spliterator covering the given range */ 1282 VectorSpliterator(Vector<E> list, Object[] array, int origin, int fence, 1283 int expectedModCount) { 1284 this.list = list; 1285 this.array = array; 1286 this.index = origin; 1287 this.fence = fence; 1288 this.expectedModCount = expectedModCount; 1289 } 1290 1291 private int getFence() { // initialize on first use 1292 int hi; 1293 if ((hi = fence) < 0) { 1294 synchronized(list) { 1295 array = list.elementData; 1296 expectedModCount = list.modCount; 1297 hi = fence = list.elementCount; 1298 } 1299 } 1300 return hi; 1301 } 1302 1303 public Spliterator<E> trySplit() { 1304 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1; 1305 return (lo >= mid) ? null : 1306 new VectorSpliterator<E>(list, array, lo, index = mid, 1307 expectedModCount); 1308 } 1309 1310 @SuppressWarnings("unchecked") 1311 public boolean tryAdvance(Consumer<? super E> action) { 1312 int i; 1313 if (action == null) 1314 throw new NullPointerException(); 1315 if (getFence() > (i = index)) { 1316 index = i + 1; 1317 action.accept((E)array[i]); 1318 if (list.modCount != expectedModCount) 1319 throw new ConcurrentModificationException(); 1320 return true; 1321 } 1322 return false; 1323 } 1324 1325 @SuppressWarnings("unchecked") 1326 public void forEachRemaining(Consumer<? super E> action) { 1327 int i, hi; // hoist accesses and checks from loop 1328 Vector<E> lst; Object[] a; 1329 if (action == null) 1330 throw new NullPointerException(); 1331 if ((lst = list) != null) { 1332 if ((hi = fence) < 0) { 1333 synchronized(lst) { 1334 expectedModCount = lst.modCount; 1335 a = array = lst.elementData; 1336 hi = fence = lst.elementCount; 1337 } 1338 } 1339 else 1340 a = array; 1341 if (a != null && (i = index) >= 0 && (index = hi) <= a.length) { 1342 while (i < hi) 1343 action.accept((E) a[i++]); 1344 if (lst.modCount == expectedModCount) 1345 return; 1346 } 1347 } 1348 throw new ConcurrentModificationException(); 1349 } 1350 1351 public long estimateSize() { 1352 return (long) (getFence() - index); 1353 } 1354 1355 public int characteristics() { 1356 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED; 1357 } 1358 } 1359 1360 @Override 1361 @SuppressWarnings("unchecked") 1362 public synchronized boolean removeIf(Predicate<? super E> filter) { 1363 Objects.requireNonNull(filter); 1364 // figure out which elements are to be removed 1365 // any exception thrown from the filter predicate at this stage 1366 // will leave the collection unmodified 1367 int removeCount = 0; 1368 final int size = elementCount; 1369 final BitSet removeSet = new BitSet(size); 1370 final int expectedModCount = modCount; 1371 for (int i=0; modCount == expectedModCount && i < size; i++) { 1372 @SuppressWarnings("unchecked") 1373 final E element = (E) elementData[i]; 1374 if (filter.test(element)) { 1375 removeSet.set(i); 1376 removeCount++; 1377 } 1378 } 1379 if (modCount != expectedModCount) { 1380 throw new ConcurrentModificationException(); 1381 } 1382 1383 // shift surviving elements left over the spaces left by removed elements 1384 final boolean anyToRemove = removeCount > 0; 1385 if (anyToRemove) { 1386 final int newSize = size - removeCount; 1387 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) { 1388 i = removeSet.nextClearBit(i); 1389 elementData[j] = elementData[i]; 1390 } 1391 for (int k=newSize; k < size; k++) { 1392 elementData[k] = null; // Let gc do its work 1393 } 1394 elementCount = newSize; 1395 if (modCount != expectedModCount) { 1396 throw new ConcurrentModificationException(); 1397 } 1398 modCount++; 1399 } 1400 1401 return anyToRemove; 1402 } 1403} 1404