1 /*
2 * Copyright (c) 1994, 2011, 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
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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 import java.util.function.Consumer;
29
30 /**
31 * The {@code Vector} class implements a growable array of
32 * objects. Like an array, it contains components that can be
33 * accessed using an integer index. However, the size of a
34 * {@code Vector} can grow or shrink as needed to accommodate
35 * adding and removing items after the {@code Vector} has been created.
36 *
37 * <p>Each vector tries to optimize storage management by maintaining a
38 * {@code capacity} and a {@code capacityIncrement}. The
39 * {@code capacity} is always at least as large as the vector
40 * size; it is usually larger because as components are added to the
41 * vector, the vector's storage increases in chunks the size of
42 * {@code capacityIncrement}. An application can increase the
43 * capacity of a vector before inserting a large number of
44 * components; this reduces the amount of incremental reallocation.
45 *
46 * <p><a name="fail-fast"/>
47 * The iterators returned by this class's {@link #iterator() iterator} and
48 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
49 * if the vector is structurally modified at any time after the iterator is
50 * created, in any way except through the iterator's own
51 * {@link ListIterator#remove() remove} or
52 * {@link ListIterator#add(Object) add} methods, the iterator will throw a
53 * {@link ConcurrentModificationException}. Thus, in the face of
54 * concurrent modification, the iterator fails quickly and cleanly, rather
55 * than risking arbitrary, non-deterministic behavior at an undetermined
56 * time in the future. The {@link Enumeration Enumerations} returned by
57 * the {@link #elements() elements} method are <em>not</em> fail-fast.
58 *
59 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
60 * as it is, generally speaking, impossible to make any hard guarantees in the
61 * presence of unsynchronized concurrent modification. Fail-fast iterators
62 * throw {@code ConcurrentModificationException} on a best-effort basis.
63 * Therefore, it would be wrong to write a program that depended on this
64 * exception for its correctness: <i>the fail-fast behavior of iterators
65 * should be used only to detect bugs.</i>
66 *
67 * <p>As of the Java 2 platform v1.2, this class was retrofitted to
68 * implement the {@link List} interface, making it a member of the
69 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
70 * Java Collections Framework</a>. Unlike the new collection
71 * implementations, {@code Vector} is synchronized. If a thread-safe
72 * implementation is not needed, it is recommended to use {@link
73 * ArrayList} in place of {@code Vector}.
74 *
75 * @author Lee Boynton
76 * @author Jonathan Payne
77 * @see Collection
78 * @see LinkedList
79 * @since JDK1.0
80 */
81 public class Vector<E>
82 extends AbstractList<E>
83 implements List<E>, RandomAccess, Cloneable, java.io.Serializable
84 {
85 /**
86 * The array buffer into which the components of the vector are
87 * stored. The capacity of the vector is the length of this array buffer,
88 * and is at least large enough to contain all the vector's elements.
89 *
90 * <p>Any array elements following the last element in the Vector are null.
91 *
92 * @serial
93 */
94 protected Object[] elementData;
95
96 /**
97 * The number of valid components in this {@code Vector} object.
98 * Components {@code elementData[0]} through
99 * {@code elementData[elementCount-1]} are the actual items.
100 *
101 * @serial
102 */
103 protected int elementCount;
104
105 /**
106 * The amount by which the capacity of the vector is automatically
107 * incremented when its size becomes greater than its capacity. If
108 * the capacity increment is less than or equal to zero, the capacity
109 * of the vector is doubled each time it needs to grow.
110 *
111 * @serial
112 */
113 protected int capacityIncrement;
114
115 /** use serialVersionUID from JDK 1.0.2 for interoperability */
116 private static final long serialVersionUID = -2767605614048989439L;
117
118 /**
119 * Constructs an empty vector with the specified initial capacity and
120 * capacity increment.
121 *
122 * @param initialCapacity the initial capacity of the vector
123 * @param capacityIncrement the amount by which the capacity is
124 * increased when the vector overflows
125 * @throws IllegalArgumentException if the specified initial capacity
126 * is negative
127 */
128 public Vector(int initialCapacity, int capacityIncrement) {
129 super();
130 if (initialCapacity < 0)
131 throw new IllegalArgumentException("Illegal Capacity: "+
132 initialCapacity);
133 this.elementData = new Object[initialCapacity];
134 this.capacityIncrement = capacityIncrement;
135 }
136
137 /**
138 * Constructs an empty vector with the specified initial capacity and
139 * with its capacity increment equal to zero.
140 *
141 * @param initialCapacity the initial capacity of the vector
142 * @throws IllegalArgumentException if the specified initial capacity
143 * is negative
144 */
145 public Vector(int initialCapacity) {
146 this(initialCapacity, 0);
147 }
148
149 /**
150 * Constructs an empty vector so that its internal data array
151 * has size {@code 10} and its standard capacity increment is
152 * zero.
153 */
154 public Vector() {
155 this(10);
156 }
157
158 /**
159 * Constructs a vector containing the elements of the specified
160 * collection, in the order they are returned by the collection's
161 * iterator.
162 *
163 * @param c the collection whose elements are to be placed into this
164 * vector
165 * @throws NullPointerException if the specified collection is null
166 * @since 1.2
167 */
168 public Vector(Collection<? extends E> c) {
169 elementData = c.toArray();
170 elementCount = elementData.length;
171 // c.toArray might (incorrectly) not return Object[] (see 6260652)
172 if (elementData.getClass() != Object[].class)
173 elementData = Arrays.copyOf(elementData, elementCount, Object[].class);
174 }
175
176 /**
177 * Copies the components of this vector into the specified array.
178 * The item at index {@code k} in this vector is copied into
179 * component {@code k} of {@code anArray}.
180 *
181 * @param anArray the array into which the components get copied
182 * @throws NullPointerException if the given array is null
183 * @throws IndexOutOfBoundsException if the specified array is not
184 * large enough to hold all the components of this vector
185 * @throws ArrayStoreException if a component of this vector is not of
186 * a runtime type that can be stored in the specified array
187 * @see #toArray(Object[])
188 */
189 public synchronized void copyInto(Object[] anArray) {
190 System.arraycopy(elementData, 0, anArray, 0, elementCount);
191 }
192
193 /**
194 * Trims the capacity of this vector to be the vector's current
195 * size. If the capacity of this vector is larger than its current
196 * size, then the capacity is changed to equal the size by replacing
197 * its internal data array, kept in the field {@code elementData},
198 * with a smaller one. An application can use this operation to
199 * minimize the storage of a vector.
200 */
201 public synchronized void trimToSize() {
202 modCount++;
203 int oldCapacity = elementData.length;
204 if (elementCount < oldCapacity) {
205 elementData = Arrays.copyOf(elementData, elementCount);
206 }
207 }
208
209 /**
210 * Increases the capacity of this vector, if necessary, to ensure
211 * that it can hold at least the number of components specified by
212 * the minimum capacity argument.
213 *
214 * <p>If the current capacity of this vector is less than
215 * {@code minCapacity}, then its capacity is increased by replacing its
216 * internal data array, kept in the field {@code elementData}, with a
217 * larger one. The size of the new data array will be the old size plus
218 * {@code capacityIncrement}, unless the value of
219 * {@code capacityIncrement} is less than or equal to zero, in which case
220 * the new capacity will be twice the old capacity; but if this new size
221 * is still smaller than {@code minCapacity}, then the new capacity will
222 * be {@code minCapacity}.
223 *
224 * @param minCapacity the desired minimum capacity
225 */
226 public synchronized void ensureCapacity(int minCapacity) {
227 if (minCapacity > 0) {
228 modCount++;
229 ensureCapacityHelper(minCapacity);
230 }
231 }
232
233 /**
234 * This implements the unsynchronized semantics of ensureCapacity.
235 * Synchronized methods in this class can internally call this
236 * method for ensuring capacity without incurring the cost of an
237 * extra synchronization.
238 *
239 * @see #ensureCapacity(int)
240 */
241 private void ensureCapacityHelper(int minCapacity) {
242 // overflow-conscious code
243 if (minCapacity - elementData.length > 0)
244 grow(minCapacity);
245 }
246
247 /**
248 * The maximum size of array to allocate.
249 * Some VMs reserve some header words in an array.
250 * Attempts to allocate larger arrays may result in
251 * OutOfMemoryError: Requested array size exceeds VM limit
252 */
253 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
254
255 private void grow(int minCapacity) {
256 // overflow-conscious code
257 int oldCapacity = elementData.length;
258 int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
259 capacityIncrement : oldCapacity);
260 if (newCapacity - minCapacity < 0)
261 newCapacity = minCapacity;
262 if (newCapacity - MAX_ARRAY_SIZE > 0)
263 newCapacity = hugeCapacity(minCapacity);
264 elementData = Arrays.copyOf(elementData, newCapacity);
265 }
266
267 private static int hugeCapacity(int minCapacity) {
268 if (minCapacity < 0) // overflow
269 throw new OutOfMemoryError();
270 return (minCapacity > MAX_ARRAY_SIZE) ?
271 Integer.MAX_VALUE :
272 MAX_ARRAY_SIZE;
273 }
274
275 /**
276 * Sets the size of this vector. If the new size is greater than the
277 * current size, new {@code null} items are added to the end of
278 * the vector. If the new size is less than the current size, all
279 * components at index {@code newSize} and greater are discarded.
280 *
281 * @param newSize the new size of this vector
282 * @throws ArrayIndexOutOfBoundsException if the new size is negative
283 */
284 public synchronized void setSize(int newSize) {
285 modCount++;
286 if (newSize > elementCount) {
287 ensureCapacityHelper(newSize);
288 } else {
289 for (int i = newSize ; i < elementCount ; i++) {
290 elementData[i] = null;
291 }
292 }
293 elementCount = newSize;
294 }
295
296 /**
297 * Returns the current capacity of this vector.
298 *
299 * @return the current capacity (the length of its internal
300 * data array, kept in the field {@code elementData}
301 * of this vector)
302 */
303 public synchronized int capacity() {
304 return elementData.length;
305 }
306
307 /**
308 * Returns the number of components in this vector.
309 *
310 * @return the number of components in this vector
311 */
312 public synchronized int size() {
313 return elementCount;
314 }
315
316 /**
317 * Tests if this vector has no components.
318 *
319 * @return {@code true} if and only if this vector has
320 * no components, that is, its size is zero;
321 * {@code false} otherwise.
322 */
323 public synchronized boolean isEmpty() {
324 return elementCount == 0;
325 }
326
327 /**
328 * Returns an enumeration of the components of this vector. The
329 * returned {@code Enumeration} object will generate all items in
330 * this vector. The first item generated is the item at index {@code 0},
331 * then the item at index {@code 1}, and so on.
332 *
333 * @return an enumeration of the components of this vector
334 * @see Iterator
335 */
336 public Enumeration<E> elements() {
337 return new Enumeration<E>() {
338 int count = 0;
339
340 public boolean hasMoreElements() {
341 return count < elementCount;
342 }
343
344 public E nextElement() {
345 synchronized (Vector.this) {
346 if (count < elementCount) {
347 return elementData(count++);
348 }
349 }
350 throw new NoSuchElementException("Vector Enumeration");
351 }
352 };
353 }
354
355 /**
356 * Returns {@code true} if this vector contains the specified element.
357 * More formally, returns {@code true} if and only if this vector
358 * contains at least one element {@code e} such that
359 * <tt>(o==null ? e==null : o.equals(e))</tt>.
360 *
361 * @param o element whose presence in this vector is to be tested
362 * @return {@code true} if this vector contains the specified element
363 */
364 public boolean contains(Object o) {
365 return indexOf(o, 0) >= 0;
366 }
367
368 /**
369 * Returns the index of the first occurrence of the specified element
370 * in this vector, or -1 if this vector does not contain the element.
371 * More formally, returns the lowest index {@code i} such that
372 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
373 * or -1 if there is no such index.
374 *
375 * @param o element to search for
376 * @return the index of the first occurrence of the specified element in
377 * this vector, or -1 if this vector does not contain the element
378 */
379 public int indexOf(Object o) {
380 return indexOf(o, 0);
381 }
382
383 /**
384 * Returns the index of the first occurrence of the specified element in
385 * this vector, searching forwards from {@code index}, or returns -1 if
386 * the element is not found.
387 * More formally, returns the lowest index {@code i} such that
388 * <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
389 * or -1 if there is no such index.
390 *
391 * @param o element to search for
392 * @param index index to start searching from
393 * @return the index of the first occurrence of the element in
394 * this vector at position {@code index} or later in the vector;
395 * {@code -1} if the element is not found.
396 * @throws IndexOutOfBoundsException if the specified index is negative
397 * @see Object#equals(Object)
398 */
399 public synchronized int indexOf(Object o, int index) {
400 if (o == null) {
401 for (int i = index ; i < elementCount ; i++)
402 if (elementData[i]==null)
403 return i;
404 } else {
405 for (int i = index ; i < elementCount ; i++)
406 if (o.equals(elementData[i]))
407 return i;
408 }
409 return -1;
410 }
411
412 /**
413 * Returns the index of the last occurrence of the specified element
414 * in this vector, or -1 if this vector does not contain the element.
415 * More formally, returns the highest index {@code i} such that
416 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
417 * or -1 if there is no such index.
418 *
419 * @param o element to search for
420 * @return the index of the last occurrence of the specified element in
421 * this vector, or -1 if this vector does not contain the element
422 */
423 public synchronized int lastIndexOf(Object o) {
424 return lastIndexOf(o, elementCount-1);
425 }
426
427 /**
428 * Returns the index of the last occurrence of the specified element in
429 * this vector, searching backwards from {@code index}, or returns -1 if
430 * the element is not found.
431 * More formally, returns the highest index {@code i} such that
432 * <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
433 * or -1 if there is no such index.
434 *
435 * @param o element to search for
436 * @param index index to start searching backwards from
437 * @return the index of the last occurrence of the element at position
438 * less than or equal to {@code index} in this vector;
439 * -1 if the element is not found.
440 * @throws IndexOutOfBoundsException if the specified index is greater
441 * than or equal to the current size of this vector
442 */
443 public synchronized int lastIndexOf(Object o, int index) {
444 if (index >= elementCount)
445 throw new IndexOutOfBoundsException(index + " >= "+ elementCount);
446
447 if (o == null) {
448 for (int i = index; i >= 0; i--)
449 if (elementData[i]==null)
450 return i;
451 } else {
452 for (int i = index; i >= 0; i--)
453 if (o.equals(elementData[i]))
454 return i;
455 }
456 return -1;
457 }
458
459 /**
460 * Returns the component at the specified index.
461 *
462 * <p>This method is identical in functionality to the {@link #get(int)}
463 * method (which is part of the {@link List} interface).
464 *
465 * @param index an index into this vector
466 * @return the component at the specified index
467 * @throws ArrayIndexOutOfBoundsException if the index is out of range
468 * ({@code index < 0 || index >= size()})
469 */
470 public synchronized E elementAt(int index) {
471 if (index >= elementCount) {
472 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
473 }
474
475 return elementData(index);
476 }
477
478 /**
479 * Returns the first component (the item at index {@code 0}) of
480 * this vector.
481 *
482 * @return the first component of this vector
483 * @throws NoSuchElementException if this vector has no components
484 */
485 public synchronized E firstElement() {
486 if (elementCount == 0) {
487 throw new NoSuchElementException();
488 }
489 return elementData(0);
490 }
491
492 /**
493 * Returns the last component of the vector.
494 *
495 * @return the last component of the vector, i.e., the component at index
496 * <code>size() - 1</code>.
497 * @throws NoSuchElementException if this vector is empty
498 */
499 public synchronized E lastElement() {
500 if (elementCount == 0) {
501 throw new NoSuchElementException();
502 }
503 return elementData(elementCount - 1);
504 }
505
506 /**
507 * Sets the component at the specified {@code index} of this
508 * vector to be the specified object. The previous component at that
509 * position is discarded.
510 *
511 * <p>The index must be a value greater than or equal to {@code 0}
512 * and less than the current size of the vector.
513 *
514 * <p>This method is identical in functionality to the
515 * {@link #set(int, Object) set(int, E)}
516 * method (which is part of the {@link List} interface). Note that the
517 * {@code set} method reverses the order of the parameters, to more closely
518 * match array usage. Note also that the {@code set} method returns the
519 * old value that was stored at the specified position.
520 *
521 * @param obj what the component is to be set to
522 * @param index the specified index
523 * @throws ArrayIndexOutOfBoundsException if the index is out of range
524 * ({@code index < 0 || index >= size()})
525 */
526 public synchronized void setElementAt(E obj, int index) {
527 if (index >= elementCount) {
528 throw new ArrayIndexOutOfBoundsException(index + " >= " +
529 elementCount);
530 }
531 elementData[index] = obj;
532 }
533
534 /**
535 * Deletes the component at the specified index. Each component in
536 * this vector with an index greater or equal to the specified
537 * {@code index} is shifted downward to have an index one
538 * smaller than the value it had previously. The size of this vector
539 * is decreased by {@code 1}.
540 *
541 * <p>The index must be a value greater than or equal to {@code 0}
542 * and less than the current size of the vector.
543 *
544 * <p>This method is identical in functionality to the {@link #remove(int)}
545 * method (which is part of the {@link List} interface). Note that the
546 * {@code remove} method returns the old value that was stored at the
547 * specified position.
548 *
549 * @param index the index of the object to remove
550 * @throws ArrayIndexOutOfBoundsException if the index is out of range
551 * ({@code index < 0 || index >= size()})
552 */
553 public synchronized void removeElementAt(int index) {
554 modCount++;
555 if (index >= elementCount) {
556 throw new ArrayIndexOutOfBoundsException(index + " >= " +
557 elementCount);
558 }
559 else if (index < 0) {
560 throw new ArrayIndexOutOfBoundsException(index);
561 }
562 int j = elementCount - index - 1;
563 if (j > 0) {
564 System.arraycopy(elementData, index + 1, elementData, index, j);
565 }
566 elementCount--;
567 elementData[elementCount] = null; /* to let gc do its work */
568 }
569
570 /**
571 * Inserts the specified object as a component in this vector at the
572 * specified {@code index}. Each component in this vector with
573 * an index greater or equal to the specified {@code index} is
574 * shifted upward to have an index one greater than the value it had
575 * previously.
576 *
577 * <p>The index must be a value greater than or equal to {@code 0}
578 * and less than or equal to the current size of the vector. (If the
579 * index is equal to the current size of the vector, the new element
580 * is appended to the Vector.)
581 *
582 * <p>This method is identical in functionality to the
583 * {@link #add(int, Object) add(int, E)}
584 * method (which is part of the {@link List} interface). Note that the
585 * {@code add} method reverses the order of the parameters, to more closely
586 * match array usage.
587 *
588 * @param obj the component to insert
589 * @param index where to insert the new component
590 * @throws ArrayIndexOutOfBoundsException if the index is out of range
591 * ({@code index < 0 || index > size()})
592 */
593 public synchronized void insertElementAt(E obj, int index) {
594 modCount++;
595 if (index > elementCount) {
596 throw new ArrayIndexOutOfBoundsException(index
597 + " > " + elementCount);
598 }
599 ensureCapacityHelper(elementCount + 1);
600 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
601 elementData[index] = obj;
602 elementCount++;
603 }
604
605 /**
606 * Adds the specified component to the end of this vector,
607 * increasing its size by one. The capacity of this vector is
608 * increased if its size becomes greater than its capacity.
609 *
610 * <p>This method is identical in functionality to the
611 * {@link #add(Object) add(E)}
612 * method (which is part of the {@link List} interface).
613 *
614 * @param obj the component to be added
615 */
616 public synchronized void addElement(E obj) {
617 modCount++;
618 ensureCapacityHelper(elementCount + 1);
619 elementData[elementCount++] = obj;
620 }
621
622 /**
623 * Removes the first (lowest-indexed) occurrence of the argument
624 * from this vector. If the object is found in this vector, each
625 * component in the vector with an index greater or equal to the
626 * object's index is shifted downward to have an index one smaller
627 * than the value it had previously.
628 *
629 * <p>This method is identical in functionality to the
630 * {@link #remove(Object)} method (which is part of the
631 * {@link List} interface).
632 *
633 * @param obj the component to be removed
634 * @return {@code true} if the argument was a component of this
635 * vector; {@code false} otherwise.
636 */
637 public synchronized boolean removeElement(Object obj) {
638 modCount++;
639 int i = indexOf(obj);
640 if (i >= 0) {
641 removeElementAt(i);
642 return true;
643 }
644 return false;
645 }
646
647 /**
648 * Removes all components from this vector and sets its size to zero.
649 *
650 * <p>This method is identical in functionality to the {@link #clear}
651 * method (which is part of the {@link List} interface).
652 */
653 public synchronized void removeAllElements() {
654 modCount++;
655 // Let gc do its work
656 for (int i = 0; i < elementCount; i++)
657 elementData[i] = null;
658
659 elementCount = 0;
660 }
661
662 /**
663 * Returns a clone of this vector. The copy will contain a
664 * reference to a clone of the internal data array, not a reference
665 * to the original internal data array of this {@code Vector} object.
666 *
667 * @return a clone of this vector
668 */
669 public synchronized Object clone() {
670 try {
671 @SuppressWarnings("unchecked")
672 Vector<E> v = (Vector<E>) super.clone();
673 v.elementData = Arrays.copyOf(elementData, elementCount);
674 v.modCount = 0;
675 return v;
676 } catch (CloneNotSupportedException e) {
677 // this shouldn't happen, since we are Cloneable
678 throw new InternalError(e);
679 }
680 }
681
682 /**
683 * Returns an array containing all of the elements in this Vector
684 * in the correct order.
685 *
686 * @since 1.2
687 */
688 public synchronized Object[] toArray() {
689 return Arrays.copyOf(elementData, elementCount);
690 }
691
692 /**
693 * Returns an array containing all of the elements in this Vector in the
694 * correct order; the runtime type of the returned array is that of the
695 * specified array. If the Vector fits in the specified array, it is
696 * returned therein. Otherwise, a new array is allocated with the runtime
697 * type of the specified array and the size of this Vector.
698 *
699 * <p>If the Vector fits in the specified array with room to spare
700 * (i.e., the array has more elements than the Vector),
701 * the element in the array immediately following the end of the
702 * Vector is set to null. (This is useful in determining the length
703 * of the Vector <em>only</em> if the caller knows that the Vector
704 * does not contain any null elements.)
705 *
706 * @param a the array into which the elements of the Vector are to
707 * be stored, if it is big enough; otherwise, a new array of the
708 * same runtime type is allocated for this purpose.
709 * @return an array containing the elements of the Vector
710 * @throws ArrayStoreException if the runtime type of a is not a supertype
711 * of the runtime type of every element in this Vector
712 * @throws NullPointerException if the given array is null
713 * @since 1.2
714 */
715 @SuppressWarnings("unchecked")
716 public synchronized <T> T[] toArray(T[] a) {
717 if (a.length < elementCount)
718 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());
719
720 System.arraycopy(elementData, 0, a, 0, elementCount);
721
722 if (a.length > elementCount)
723 a[elementCount] = null;
724
725 return a;
726 }
727
728 // Positional Access Operations
729
730 @SuppressWarnings("unchecked")
731 E elementData(int index) {
732 return (E) elementData[index];
733 }
734
735 /**
736 * Returns the element at the specified position in this Vector.
737 *
738 * @param index index of the element to return
739 * @return object at the specified index
740 * @throws ArrayIndexOutOfBoundsException if the index is out of range
741 * ({@code index < 0 || index >= size()})
742 * @since 1.2
743 */
744 public synchronized E get(int index) {
745 if (index >= elementCount)
746 throw new ArrayIndexOutOfBoundsException(index);
747
748 return elementData(index);
749 }
750
751 /**
752 * Replaces the element at the specified position in this Vector with the
753 * specified element.
754 *
755 * @param index index of the element to replace
756 * @param element element to be stored at the specified position
757 * @return the element previously at the specified position
758 * @throws ArrayIndexOutOfBoundsException if the index is out of range
759 * ({@code index < 0 || index >= size()})
760 * @since 1.2
761 */
762 public synchronized E set(int index, E element) {
763 if (index >= elementCount)
764 throw new ArrayIndexOutOfBoundsException(index);
765
766 E oldValue = elementData(index);
767 elementData[index] = element;
768 return oldValue;
769 }
770
771 /**
772 * Appends the specified element to the end of this Vector.
773 *
774 * @param e element to be appended to this Vector
775 * @return {@code true} (as specified by {@link Collection#add})
776 * @since 1.2
777 */
778 public synchronized boolean add(E e) {
779 modCount++;
780 ensureCapacityHelper(elementCount + 1);
781 elementData[elementCount++] = e;
782 return true;
783 }
784
785 /**
786 * Removes the first occurrence of the specified element in this Vector
787 * If the Vector does not contain the element, it is unchanged. More
788 * formally, removes the element with the lowest index i such that
789 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such
790 * an element exists).
791 *
792 * @param o element to be removed from this Vector, if present
793 * @return true if the Vector contained the specified element
794 * @since 1.2
795 */
796 public boolean remove(Object o) {
797 return removeElement(o);
798 }
799
800 /**
801 * Inserts the specified element at the specified position in this Vector.
802 * Shifts the element currently at that position (if any) and any
803 * subsequent elements to the right (adds one to their indices).
804 *
805 * @param index index at which the specified element is to be inserted
806 * @param element element to be inserted
807 * @throws ArrayIndexOutOfBoundsException if the index is out of range
808 * ({@code index < 0 || index > size()})
809 * @since 1.2
810 */
811 public void add(int index, E element) {
812 insertElementAt(element, index);
813 }
814
815 /**
816 * Removes the element at the specified position in this Vector.
817 * Shifts any subsequent elements to the left (subtracts one from their
818 * indices). Returns the element that was removed from the Vector.
819 *
820 * @throws ArrayIndexOutOfBoundsException if the index is out of range
821 * ({@code index < 0 || index >= size()})
822 * @param index the index of the element to be removed
823 * @return element that was removed
824 * @since 1.2
825 */
826 public synchronized E remove(int index) {
827 modCount++;
828 if (index >= elementCount)
829 throw new ArrayIndexOutOfBoundsException(index);
830 E oldValue = elementData(index);
831
832 int numMoved = elementCount - index - 1;
833 if (numMoved > 0)
834 System.arraycopy(elementData, index+1, elementData, index,
835 numMoved);
836 elementData[--elementCount] = null; // Let gc do its work
837
838 return oldValue;
839 }
840
841 /**
842 * Removes all of the elements from this Vector. The Vector will
843 * be empty after this call returns (unless it throws an exception).
844 *
845 * @since 1.2
846 */
847 public void clear() {
848 removeAllElements();
849 }
850
851 // Bulk Operations
852
853 /**
854 * Returns true if this Vector contains all of the elements in the
855 * specified Collection.
856 *
857 * @param c a collection whose elements will be tested for containment
858 * in this Vector
859 * @return true if this Vector contains all of the elements in the
860 * specified collection
861 * @throws NullPointerException if the specified collection is null
862 */
863 public synchronized boolean containsAll(Collection<?> c) {
864 return super.containsAll(c);
865 }
866
867 /**
868 * Appends all of the elements in the specified Collection to the end of
869 * this Vector, in the order that they are returned by the specified
870 * Collection's Iterator. The behavior of this operation is undefined if
871 * the specified Collection is modified while the operation is in progress.
872 * (This implies that the behavior of this call is undefined if the
873 * specified Collection is this Vector, and this Vector is nonempty.)
874 *
875 * @param c elements to be inserted into this Vector
876 * @return {@code true} if this Vector changed as a result of the call
877 * @throws NullPointerException if the specified collection is null
878 * @since 1.2
879 */
880 public synchronized boolean addAll(Collection<? extends E> c) {
881 modCount++;
882 Object[] a = c.toArray();
883 int numNew = a.length;
884 ensureCapacityHelper(elementCount + numNew);
885 System.arraycopy(a, 0, elementData, elementCount, numNew);
886 elementCount += numNew;
887 return numNew != 0;
888 }
889
890 /**
891 * Removes from this Vector all of its elements that are contained in the
892 * specified Collection.
893 *
894 * @param c a collection of elements to be removed from the Vector
895 * @return true if this Vector changed as a result of the call
896 * @throws ClassCastException if the types of one or more elements
897 * in this vector are incompatible with the specified
898 * collection
899 * (<a href="Collection.html#optional-restrictions">optional</a>)
900 * @throws NullPointerException if this vector contains one or more null
901 * elements and the specified collection does not support null
902 * elements
903 * (<a href="Collection.html#optional-restrictions">optional</a>),
904 * or if the specified collection is null
905 * @since 1.2
906 */
907 public synchronized boolean removeAll(Collection<?> c) {
908 return super.removeAll(c);
909 }
910
911 /**
912 * Retains only the elements in this Vector that are contained in the
913 * specified Collection. In other words, removes from this Vector all
914 * of its elements that are not contained in the specified Collection.
915 *
916 * @param c a collection of elements to be retained in this Vector
917 * (all other elements are removed)
918 * @return true if this Vector changed as a result of the call
919 * @throws ClassCastException if the types of one or more elements
920 * in this vector are incompatible with the specified
921 * collection
922 * (<a href="Collection.html#optional-restrictions">optional</a>)
923 * @throws NullPointerException if this vector contains one or more null
924 * elements and the specified collection does not support null
925 * elements
926 * (<a href="Collection.html#optional-restrictions">optional</a>),
927 * or if the specified collection is null
928 * @since 1.2
929 */
930 public synchronized boolean retainAll(Collection<?> c) {
931 return super.retainAll(c);
932 }
933
934 /**
935 * Inserts all of the elements in the specified Collection into this
936 * Vector at the specified position. Shifts the element currently at
937 * that position (if any) and any subsequent elements to the right
938 * (increases their indices). The new elements will appear in the Vector
939 * in the order that they are returned by the specified Collection's
940 * iterator.
941 *
942 * @param index index at which to insert the first element from the
943 * specified collection
944 * @param c elements to be inserted into this Vector
945 * @return {@code true} if this Vector changed as a result of the call
946 * @throws ArrayIndexOutOfBoundsException if the index is out of range
947 * ({@code index < 0 || index > size()})
948 * @throws NullPointerException if the specified collection is null
949 * @since 1.2
950 */
951 public synchronized boolean addAll(int index, Collection<? extends E> c) {
952 modCount++;
953 if (index < 0 || index > elementCount)
954 throw new ArrayIndexOutOfBoundsException(index);
955
956 Object[] a = c.toArray();
957 int numNew = a.length;
958 ensureCapacityHelper(elementCount + numNew);
959
960 int numMoved = elementCount - index;
961 if (numMoved > 0)
962 System.arraycopy(elementData, index, elementData, index + numNew,
963 numMoved);
964
965 System.arraycopy(a, 0, elementData, index, numNew);
966 elementCount += numNew;
967 return numNew != 0;
968 }
969
970 /**
971 * Compares the specified Object with this Vector for equality. Returns
972 * true if and only if the specified Object is also a List, both Lists
973 * have the same size, and all corresponding pairs of elements in the two
974 * Lists are <em>equal</em>. (Two elements {@code e1} and
975 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null :
976 * e1.equals(e2))}.) In other words, two Lists are defined to be
977 * equal if they contain the same elements in the same order.
978 *
979 * @param o the Object to be compared for equality with this Vector
980 * @return true if the specified Object is equal to this Vector
981 */
982 public synchronized boolean equals(Object o) {
983 return super.equals(o);
984 }
985
986 /**
987 * Returns the hash code value for this Vector.
988 */
989 public synchronized int hashCode() {
990 return super.hashCode();
991 }
992
993 /**
994 * Returns a string representation of this Vector, containing
995 * the String representation of each element.
996 */
997 public synchronized String toString() {
998 return super.toString();
999 }
1000
1001 /**
1002 * Returns a view of the portion of this List between fromIndex,
1003 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are
1004 * equal, the returned List is empty.) The returned List is backed by this
1005 * List, so changes in the returned List are reflected in this List, and
1006 * vice-versa. The returned List supports all of the optional List
1007 * operations supported by this List.
1008 *
1009 * <p>This method eliminates the need for explicit range operations (of
1010 * the sort that commonly exist for arrays). Any operation that expects
1011 * a List can be used as a range operation by operating on a subList view
1012 * instead of a whole List. For example, the following idiom
1013 * removes a range of elements from a List:
1014 * <pre>
1015 * list.subList(from, to).clear();
1016 * </pre>
1017 * Similar idioms may be constructed for indexOf and lastIndexOf,
1018 * and all of the algorithms in the Collections class can be applied to
1019 * a subList.
1020 *
1021 * <p>The semantics of the List returned by this method become undefined if
1022 * the backing list (i.e., this List) is <i>structurally modified</i> in
1023 * any way other than via the returned List. (Structural modifications are
1024 * those that change the size of the List, or otherwise perturb it in such
1025 * a fashion that iterations in progress may yield incorrect results.)
1026 *
1027 * @param fromIndex low endpoint (inclusive) of the subList
1028 * @param toIndex high endpoint (exclusive) of the subList
1029 * @return a view of the specified range within this List
1030 * @throws IndexOutOfBoundsException if an endpoint index value is out of range
1031 * {@code (fromIndex < 0 || toIndex > size)}
1032 * @throws IllegalArgumentException if the endpoint indices are out of order
1033 * {@code (fromIndex > toIndex)}
1034 */
1035 public synchronized List<E> subList(int fromIndex, int toIndex) {
1036 return Collections.synchronizedList(super.subList(fromIndex, toIndex),
1037 this);
1038 }
1039
1040 /**
1041 * Removes from this list all of the elements whose index is between
1042 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
1043 * Shifts any succeeding elements to the left (reduces their index).
1044 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
1045 * (If {@code toIndex==fromIndex}, this operation has no effect.)
1046 */
1047 protected synchronized void removeRange(int fromIndex, int toIndex) {
1048 modCount++;
1049 int numMoved = elementCount - toIndex;
1050 System.arraycopy(elementData, toIndex, elementData, fromIndex,
1051 numMoved);
1052
1053 // Let gc do its work
1054 int newElementCount = elementCount - (toIndex-fromIndex);
1055 while (elementCount != newElementCount)
1056 elementData[--elementCount] = null;
1057 }
1058
1059 /**
1060 * Save the state of the {@code Vector} instance to a stream (that
1061 * is, serialize it).
1062 * This method performs synchronization to ensure the consistency
1063 * of the serialized data.
1064 */
1065 private void writeObject(java.io.ObjectOutputStream s)
1066 throws java.io.IOException {
1067 final java.io.ObjectOutputStream.PutField fields = s.putFields();
1068 final Object[] data;
1069 synchronized (this) {
1070 fields.put("capacityIncrement", capacityIncrement);
1071 fields.put("elementCount", elementCount);
1072 data = elementData.clone();
1073 }
1074 fields.put("elementData", data);
1075 s.writeFields();
1076 }
1077
1078 /**
1079 * Returns a list iterator over the elements in this list (in proper
1080 * sequence), starting at the specified position in the list.
1081 * The specified index indicates the first element that would be
1082 * returned by an initial call to {@link ListIterator#next next}.
1083 * An initial call to {@link ListIterator#previous previous} would
1084 * return the element with the specified index minus one.
1085 *
1086 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1087 *
1088 * @throws IndexOutOfBoundsException {@inheritDoc}
1089 */
1090 public synchronized ListIterator<E> listIterator(int index) {
1091 if (index < 0 || index > elementCount)
1092 throw new IndexOutOfBoundsException("Index: "+index);
1093 return new ListItr(index);
1094 }
1095
1096 /**
1097 * Returns a list iterator over the elements in this list (in proper
1098 * sequence).
1099 *
1100 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1101 *
1102 * @see #listIterator(int)
1103 */
1104 public synchronized ListIterator<E> listIterator() {
1105 return new ListItr(0);
1106 }
1107
1108 /**
1109 * Returns an iterator over the elements in this list in proper sequence.
1110 *
1111 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1112 *
1113 * @return an iterator over the elements in this list in proper sequence
1114 */
1115 public synchronized Iterator<E> iterator() {
1116 return new Itr();
1117 }
1118
1119 /**
1120 * An optimized version of AbstractList.Itr
1121 */
1122 private class Itr implements Iterator<E> {
1123 int cursor; // index of next element to return
1124 int lastRet = -1; // index of last element returned; -1 if no such
1125 int expectedModCount = modCount;
1126
1127 public boolean hasNext() {
1128 // Racy but within spec, since modifications are checked
1129 // within or after synchronization in next/previous
1130 return cursor != elementCount;
1131 }
1132
1133 public E next() {
1134 synchronized (Vector.this) {
1135 checkForComodification();
1136 int i = cursor;
1137 if (i >= elementCount)
1138 throw new NoSuchElementException();
1139 cursor = i + 1;
1140 return elementData(lastRet = i);
1141 }
1142 }
1143
1144 public void remove() {
1145 if (lastRet == -1)
1146 throw new IllegalStateException();
1147 synchronized (Vector.this) {
1148 checkForComodification();
1149 Vector.this.remove(lastRet);
1150 expectedModCount = modCount;
1151 }
1152 cursor = lastRet;
1153 lastRet = -1;
1154 }
1155
1156 @Override
1157 public void forEachRemaining(Consumer<? super E> action) {
1158 Objects.requireNonNull(action);
1159 synchronized (Vector.this) {
1160 final int size = Vector.this.elementCount;
1161 int i = cursor;
1162 if (i >= size) {
1163 return;
1164 }
1165 final Object[] elementData = Vector.this.elementData;
1166 if (i >= elementData.length) {
1167 throw new ConcurrentModificationException();
1168 }
1169 while (i != size && modCount == expectedModCount) {
1170 action.accept((E) elementData[i++]);
1171 }
1172 // update once at end of iteration to reduce heap write traffic
1173 lastRet = cursor = i;
1174 checkForComodification();
1175 }
1176 }
1177
1178 final void checkForComodification() {
1179 if (modCount != expectedModCount)
1180 throw new ConcurrentModificationException();
1181 }
1182 }
1183
1184 /**
1185 * An optimized version of AbstractList.ListItr
1186 */
1187 final class ListItr extends Itr implements ListIterator<E> {
1188 ListItr(int index) {
1189 super();
1190 cursor = index;
1191 }
1192
1193 public boolean hasPrevious() {
1194 return cursor != 0;
1195 }
1196
1197 public int nextIndex() {
1198 return cursor;
1199 }
1200
1201 public int previousIndex() {
1202 return cursor - 1;
1203 }
1204
1205 public E previous() {
1206 synchronized (Vector.this) {
1207 checkForComodification();
1208 int i = cursor - 1;
1209 if (i < 0)
1210 throw new NoSuchElementException();
1211 cursor = i;
1212 return elementData(lastRet = i);
1213 }
1214 }
1215
1216 public void set(E e) {
1217 if (lastRet == -1)
1218 throw new IllegalStateException();
1219 synchronized (Vector.this) {
1220 checkForComodification();
1221 Vector.this.set(lastRet, e);
1222 }
1223 }
1224
1225 public void add(E e) {
1226 int i = cursor;
1227 synchronized (Vector.this) {
1228 checkForComodification();
1229 Vector.this.add(i, e);
1230 expectedModCount = modCount;
1231 }
1232 cursor = i + 1;
1233 lastRet = -1;
1234 }
1235 }
1236 }