1 /*
2 * Copyright 1994-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.util;
27
28 /**
29 * The {@code Vector} class implements a growable array of
30 * objects. Like an array, it contains components that can be
31 * accessed using an integer index. However, the size of a
32 * {@code Vector} can grow or shrink as needed to accommodate
33 * adding and removing items after the {@code Vector} has been created.
34 *
35 * <p>Each vector tries to optimize storage management by maintaining a
36 * {@code capacity} and a {@code capacityIncrement}. The
37 * {@code capacity} is always at least as large as the vector
38 * size; it is usually larger because as components are added to the
39 * vector, the vector's storage increases in chunks the size of
40 * {@code capacityIncrement}. An application can increase the
41 * capacity of a vector before inserting a large number of
42 * components; this reduces the amount of incremental reallocation.
43 *
44 * <p><a name="fail-fast"/>
45 * The iterators returned by this class's {@link #iterator() iterator} and
46 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
47 * if the vector is structurally modified at any time after the iterator is
48 * created, in any way except through the iterator's own
49 * {@link ListIterator#remove() remove} or
50 * {@link ListIterator#add(Object) add} methods, the iterator will throw a
51 * {@link ConcurrentModificationException}. Thus, in the face of
52 * concurrent modification, the iterator fails quickly and cleanly, rather
53 * than risking arbitrary, non-deterministic behavior at an undetermined
54 * time in the future. The {@link Enumeration Enumerations} returned by
55 * the {@link #elements() elements} method are <em>not</em> fail-fast.
56 *
57 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
58 * as it is, generally speaking, impossible to make any hard guarantees in the
59 * presence of unsynchronized concurrent modification. Fail-fast iterators
60 * throw {@code ConcurrentModificationException} on a best-effort basis.
61 * Therefore, it would be wrong to write a program that depended on this
62 * exception for its correctness: <i>the fail-fast behavior of iterators
63 * should be used only to detect bugs.</i>
64 *
65 * <p>As of the Java 2 platform v1.2, this class was retrofitted to
66 * implement the {@link List} interface, making it a member of the
67 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
68 * Java Collections Framework</a>. Unlike the new collection
69 * implementations, {@code Vector} is synchronized. If a thread-safe
70 * implementation is not needed, it is recommended to use {@link
71 * ArrayList} in place of {@code Vector}.
72 *
73 * @author Lee Boynton
74 * @author Jonathan Payne
75 * @see Collection
76 * @see LinkedList
77 * @since JDK1.0
78 */
79 public class Vector<E>
80 extends AbstractList<E>
81 implements List<E>, RandomAccess, Cloneable, java.io.Serializable
82 {
83 /**
84 * The array buffer into which the components of the vector are
85 * stored. The capacity of the vector is the length of this array buffer,
86 * and is at least large enough to contain all the vector's elements.
87 *
88 * <p>Any array elements following the last element in the Vector are null.
89 *
90 * @serial
91 */
92 protected Object[] elementData;
93
94 /**
95 * The number of valid components in this {@code Vector} object.
96 * Components {@code elementData[0]} through
97 * {@code elementData[elementCount-1]} are the actual items.
98 *
99 * @serial
100 */
101 protected int elementCount;
102
103 /**
104 * The amount by which the capacity of the vector is automatically
105 * incremented when its size becomes greater than its capacity. If
106 * the capacity increment is less than or equal to zero, the capacity
107 * of the vector is doubled each time it needs to grow.
108 *
109 * @serial
110 */
111 protected int capacityIncrement;
112
113 /** use serialVersionUID from JDK 1.0.2 for interoperability */
114 private static final long serialVersionUID = -2767605614048989439L;
115
116 /**
117 * Constructs an empty vector with the specified initial capacity and
118 * capacity increment.
119 *
120 * @param initialCapacity the initial capacity of the vector
121 * @param capacityIncrement the amount by which the capacity is
122 * increased when the vector overflows
123 * @throws IllegalArgumentException if the specified initial capacity
124 * is negative
125 */
126 public Vector(int initialCapacity, int capacityIncrement) {
127 super();
128 if (initialCapacity < 0)
129 throw new IllegalArgumentException("Illegal Capacity: "+
130 initialCapacity);
131 this.elementData = new Object[initialCapacity];
132 this.capacityIncrement = capacityIncrement;
133 }
134
135 /**
136 * Constructs an empty vector with the specified initial capacity and
137 * with its capacity increment equal to zero.
138 *
139 * @param initialCapacity the initial capacity of the vector
140 * @throws IllegalArgumentException if the specified initial capacity
141 * is negative
142 */
143 public Vector(int initialCapacity) {
144 this(initialCapacity, 0);
145 }
146
147 /**
148 * Constructs an empty vector so that its internal data array
149 * has size {@code 10} and its standard capacity increment is
150 * zero.
151 */
152 public Vector() {
153 this(10);
154 }
155
156 /**
157 * Constructs a vector containing the elements of the specified
158 * collection, in the order they are returned by the collection's
159 * iterator.
160 *
161 * @param c the collection whose elements are to be placed into this
162 * vector
163 * @throws NullPointerException if the specified collection is null
164 * @since 1.2
165 */
166 public Vector(Collection<? extends E> c) {
167 elementData = c.toArray();
168 elementCount = elementData.length;
169 // c.toArray might (incorrectly) not return Object[] (see 6260652)
170 if (elementData.getClass() != Object[].class)
171 elementData = Arrays.copyOf(elementData, elementCount, Object[].class);
172 }
173
174 /**
175 * Copies the components of this vector into the specified array.
176 * The item at index {@code k} in this vector is copied into
177 * component {@code k} of {@code anArray}.
178 *
179 * @param anArray the array into which the components get copied
180 * @throws NullPointerException if the given array is null
181 * @throws IndexOutOfBoundsException if the specified array is not
182 * large enough to hold all the components of this vector
183 * @throws ArrayStoreException if a component of this vector is not of
184 * a runtime type that can be stored in the specified array
185 * @see #toArray(Object[])
186 */
187 public synchronized void copyInto(Object[] anArray) {
188 System.arraycopy(elementData, 0, anArray, 0, elementCount);
189 }
190
191 /**
192 * Trims the capacity of this vector to be the vector's current
193 * size. If the capacity of this vector is larger than its current
194 * size, then the capacity is changed to equal the size by replacing
195 * its internal data array, kept in the field {@code elementData},
196 * with a smaller one. An application can use this operation to
197 * minimize the storage of a vector.
198 */
199 public synchronized void trimToSize() {
200 modCount++;
201 int oldCapacity = elementData.length;
202 if (elementCount < oldCapacity) {
203 elementData = Arrays.copyOf(elementData, elementCount);
204 }
205 }
206
207 /**
208 * Increases the capacity of this vector, if necessary, to ensure
209 * that it can hold at least the number of components specified by
210 * the minimum capacity argument.
211 *
212 * <p>If the current capacity of this vector is less than
213 * {@code minCapacity}, then its capacity is increased by replacing its
214 * internal data array, kept in the field {@code elementData}, with a
215 * larger one. The size of the new data array will be the old size plus
216 * {@code capacityIncrement}, unless the value of
217 * {@code capacityIncrement} is less than or equal to zero, in which case
218 * the new capacity will be twice the old capacity; but if this new size
219 * is still smaller than {@code minCapacity}, then the new capacity will
220 * be {@code minCapacity}.
221 *
222 * @param minCapacity the desired minimum capacity
223 */
224 public synchronized void ensureCapacity(int minCapacity) {
225 modCount++;
226 ensureCapacityHelper(minCapacity);
227 }
228
229 /**
230 * This implements the unsynchronized semantics of ensureCapacity.
231 * Synchronized methods in this class can internally call this
232 * method for ensuring capacity without incurring the cost of an
233 * extra synchronization.
234 *
235 * @see #ensureCapacity(int)
236 */
237 private void ensureCapacityHelper(int minCapacity) {
238 int oldCapacity = elementData.length;
239 if (minCapacity > oldCapacity) {
240 Object[] oldData = elementData;
241 int newCapacity = (capacityIncrement > 0) ?
242 (oldCapacity + capacityIncrement) : (oldCapacity * 2);
243 if (newCapacity < minCapacity) {
244 newCapacity = minCapacity;
245 }
246 elementData = Arrays.copyOf(elementData, newCapacity);
247 }
248 }
249
250 /**
251 * Sets the size of this vector. If the new size is greater than the
252 * current size, new {@code null} items are added to the end of
253 * the vector. If the new size is less than the current size, all
254 * components at index {@code newSize} and greater are discarded.
255 *
256 * @param newSize the new size of this vector
257 * @throws ArrayIndexOutOfBoundsException if the new size is negative
258 */
259 public synchronized void setSize(int newSize) {
260 modCount++;
261 if (newSize > elementCount) {
262 ensureCapacityHelper(newSize);
263 } else {
264 for (int i = newSize ; i < elementCount ; i++) {
265 elementData[i] = null;
266 }
267 }
268 elementCount = newSize;
269 }
270
271 /**
272 * Returns the current capacity of this vector.
273 *
274 * @return the current capacity (the length of its internal
275 * data array, kept in the field {@code elementData}
276 * of this vector)
277 */
278 public synchronized int capacity() {
279 return elementData.length;
280 }
281
282 /**
283 * Returns the number of components in this vector.
284 *
285 * @return the number of components in this vector
286 */
287 public synchronized int size() {
288 return elementCount;
289 }
290
291 /**
292 * Tests if this vector has no components.
293 *
294 * @return {@code true} if and only if this vector has
295 * no components, that is, its size is zero;
296 * {@code false} otherwise.
297 */
298 public synchronized boolean isEmpty() {
299 return elementCount == 0;
300 }
301
302 /**
303 * Returns an enumeration of the components of this vector. The
304 * returned {@code Enumeration} object will generate all items in
305 * this vector. The first item generated is the item at index {@code 0},
306 * then the item at index {@code 1}, and so on.
307 *
308 * @return an enumeration of the components of this vector
309 * @see Iterator
310 */
311 public Enumeration<E> elements() {
312 return new Enumeration<E>() {
313 int count = 0;
314
315 public boolean hasMoreElements() {
316 return count < elementCount;
317 }
318
319 public E nextElement() {
320 synchronized (Vector.this) {
321 if (count < elementCount) {
322 return elementData(count++);
323 }
324 }
325 throw new NoSuchElementException("Vector Enumeration");
326 }
327 };
328 }
329
330 /**
331 * Returns {@code true} if this vector contains the specified element.
332 * More formally, returns {@code true} if and only if this vector
333 * contains at least one element {@code e} such that
334 * <tt>(o==null ? e==null : o.equals(e))</tt>.
335 *
336 * @param o element whose presence in this vector is to be tested
337 * @return {@code true} if this vector contains the specified element
338 */
339 public boolean contains(Object o) {
340 return indexOf(o, 0) >= 0;
341 }
342
343 /**
344 * Returns the index of the first occurrence of the specified element
345 * in this vector, or -1 if this vector does not contain the element.
346 * More formally, returns the lowest index {@code i} such that
347 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
348 * or -1 if there is no such index.
349 *
350 * @param o element to search for
351 * @return the index of the first occurrence of the specified element in
352 * this vector, or -1 if this vector does not contain the element
353 */
354 public int indexOf(Object o) {
355 return indexOf(o, 0);
356 }
357
358 /**
359 * Returns the index of the first occurrence of the specified element in
360 * this vector, searching forwards from {@code index}, or returns -1 if
361 * the element is not found.
362 * More formally, returns the lowest index {@code i} such that
363 * <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
364 * or -1 if there is no such index.
365 *
366 * @param o element to search for
367 * @param index index to start searching from
368 * @return the index of the first occurrence of the element in
369 * this vector at position {@code index} or later in the vector;
370 * {@code -1} if the element is not found.
371 * @throws IndexOutOfBoundsException if the specified index is negative
372 * @see Object#equals(Object)
373 */
374 public synchronized int indexOf(Object o, int index) {
375 if (o == null) {
376 for (int i = index ; i < elementCount ; i++)
377 if (elementData[i]==null)
378 return i;
379 } else {
380 for (int i = index ; i < elementCount ; i++)
381 if (o.equals(elementData[i]))
382 return i;
383 }
384 return -1;
385 }
386
387 /**
388 * Returns the index of the last occurrence of the specified element
389 * in this vector, or -1 if this vector does not contain the element.
390 * More formally, returns the highest index {@code i} such that
391 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
392 * or -1 if there is no such index.
393 *
394 * @param o element to search for
395 * @return the index of the last occurrence of the specified element in
396 * this vector, or -1 if this vector does not contain the element
397 */
398 public synchronized int lastIndexOf(Object o) {
399 return lastIndexOf(o, elementCount-1);
400 }
401
402 /**
403 * Returns the index of the last occurrence of the specified element in
404 * this vector, searching backwards from {@code index}, or returns -1 if
405 * the element is not found.
406 * More formally, returns the highest index {@code i} such that
407 * <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
408 * or -1 if there is no such index.
409 *
410 * @param o element to search for
411 * @param index index to start searching backwards from
412 * @return the index of the last occurrence of the element at position
413 * less than or equal to {@code index} in this vector;
414 * -1 if the element is not found.
415 * @throws IndexOutOfBoundsException if the specified index is greater
416 * than or equal to the current size of this vector
417 */
418 public synchronized int lastIndexOf(Object o, int index) {
419 if (index >= elementCount)
420 throw new IndexOutOfBoundsException(index + " >= "+ elementCount);
421
422 if (o == null) {
423 for (int i = index; i >= 0; i--)
424 if (elementData[i]==null)
425 return i;
426 } else {
427 for (int i = index; i >= 0; i--)
428 if (o.equals(elementData[i]))
429 return i;
430 }
431 return -1;
432 }
433
434 /**
435 * Returns the component at the specified index.
436 *
437 * <p>This method is identical in functionality to the {@link #get(int)}
438 * method (which is part of the {@link List} interface).
439 *
440 * @param index an index into this vector
441 * @return the component at the specified index
442 * @throws ArrayIndexOutOfBoundsException if the index is out of range
443 * ({@code index < 0 || index >= size()})
444 */
445 public synchronized E elementAt(int index) {
446 if (index >= elementCount) {
447 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
448 }
449
450 return elementData(index);
451 }
452
453 /**
454 * Returns the first component (the item at index {@code 0}) of
455 * this vector.
456 *
457 * @return the first component of this vector
458 * @throws NoSuchElementException if this vector has no components
459 */
460 public synchronized E firstElement() {
461 if (elementCount == 0) {
462 throw new NoSuchElementException();
463 }
464 return elementData(0);
465 }
466
467 /**
468 * Returns the last component of the vector.
469 *
470 * @return the last component of the vector, i.e., the component at index
471 * <code>size() - 1</code>.
472 * @throws NoSuchElementException if this vector is empty
473 */
474 public synchronized E lastElement() {
475 if (elementCount == 0) {
476 throw new NoSuchElementException();
477 }
478 return elementData(elementCount - 1);
479 }
480
481 /**
482 * Sets the component at the specified {@code index} of this
483 * vector to be the specified object. The previous component at that
484 * position is discarded.
485 *
486 * <p>The index must be a value greater than or equal to {@code 0}
487 * and less than the current size of the vector.
488 *
489 * <p>This method is identical in functionality to the
490 * {@link #set(int, Object) set(int, E)}
491 * method (which is part of the {@link List} interface). Note that the
492 * {@code set} method reverses the order of the parameters, to more closely
493 * match array usage. Note also that the {@code set} method returns the
494 * old value that was stored at the specified position.
495 *
496 * @param obj what the component is to be set to
497 * @param index the specified index
498 * @throws ArrayIndexOutOfBoundsException if the index is out of range
499 * ({@code index < 0 || index >= size()})
500 */
501 public synchronized void setElementAt(E obj, int index) {
502 if (index >= elementCount) {
503 throw new ArrayIndexOutOfBoundsException(index + " >= " +
504 elementCount);
505 }
506 elementData[index] = obj;
507 }
508
509 /**
510 * Deletes the component at the specified index. Each component in
511 * this vector with an index greater or equal to the specified
512 * {@code index} is shifted downward to have an index one
513 * smaller than the value it had previously. The size of this vector
514 * is decreased by {@code 1}.
515 *
516 * <p>The index must be a value greater than or equal to {@code 0}
517 * and less than the current size of the vector.
518 *
519 * <p>This method is identical in functionality to the {@link #remove(int)}
520 * method (which is part of the {@link List} interface). Note that the
521 * {@code remove} method returns the old value that was stored at the
522 * specified position.
523 *
524 * @param index the index of the object to remove
525 * @throws ArrayIndexOutOfBoundsException if the index is out of range
526 * ({@code index < 0 || index >= size()})
527 */
528 public synchronized void removeElementAt(int index) {
529 modCount++;
530 if (index >= elementCount) {
531 throw new ArrayIndexOutOfBoundsException(index + " >= " +
532 elementCount);
533 }
534 else if (index < 0) {
535 throw new ArrayIndexOutOfBoundsException(index);
536 }
537 int j = elementCount - index - 1;
538 if (j > 0) {
539 System.arraycopy(elementData, index + 1, elementData, index, j);
540 }
541 elementCount--;
542 elementData[elementCount] = null; /* to let gc do its work */
543 }
544
545 /**
546 * Inserts the specified object as a component in this vector at the
547 * specified {@code index}. Each component in this vector with
548 * an index greater or equal to the specified {@code index} is
549 * shifted upward to have an index one greater than the value it had
550 * previously.
551 *
552 * <p>The index must be a value greater than or equal to {@code 0}
553 * and less than or equal to the current size of the vector. (If the
554 * index is equal to the current size of the vector, the new element
555 * is appended to the Vector.)
556 *
557 * <p>This method is identical in functionality to the
558 * {@link #add(int, Object) add(int, E)}
559 * method (which is part of the {@link List} interface). Note that the
560 * {@code add} method reverses the order of the parameters, to more closely
561 * match array usage.
562 *
563 * @param obj the component to insert
564 * @param index where to insert the new component
565 * @throws ArrayIndexOutOfBoundsException if the index is out of range
566 * ({@code index < 0 || index > size()})
567 */
568 public synchronized void insertElementAt(E obj, int index) {
569 modCount++;
570 if (index > elementCount) {
571 throw new ArrayIndexOutOfBoundsException(index
572 + " > " + elementCount);
573 }
574 ensureCapacityHelper(elementCount + 1);
575 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
576 elementData[index] = obj;
577 elementCount++;
578 }
579
580 /**
581 * Adds the specified component to the end of this vector,
582 * increasing its size by one. The capacity of this vector is
583 * increased if its size becomes greater than its capacity.
584 *
585 * <p>This method is identical in functionality to the
586 * {@link #add(Object) add(E)}
587 * method (which is part of the {@link List} interface).
588 *
589 * @param obj the component to be added
590 */
591 public synchronized void addElement(E obj) {
592 modCount++;
593 ensureCapacityHelper(elementCount + 1);
594 elementData[elementCount++] = obj;
595 }
596
597 /**
598 * Removes the first (lowest-indexed) occurrence of the argument
599 * from this vector. If the object is found in this vector, each
600 * component in the vector with an index greater or equal to the
601 * object's index is shifted downward to have an index one smaller
602 * than the value it had previously.
603 *
604 * <p>This method is identical in functionality to the
605 * {@link #remove(Object)} method (which is part of the
606 * {@link List} interface).
607 *
608 * @param obj the component to be removed
609 * @return {@code true} if the argument was a component of this
610 * vector; {@code false} otherwise.
611 */
612 public synchronized boolean removeElement(Object obj) {
613 modCount++;
614 int i = indexOf(obj);
615 if (i >= 0) {
616 removeElementAt(i);
617 return true;
618 }
619 return false;
620 }
621
622 /**
623 * Removes all components from this vector and sets its size to zero.
624 *
625 * <p>This method is identical in functionality to the {@link #clear}
626 * method (which is part of the {@link List} interface).
627 */
628 public synchronized void removeAllElements() {
629 modCount++;
630 // Let gc do its work
631 for (int i = 0; i < elementCount; i++)
632 elementData[i] = null;
633
634 elementCount = 0;
635 }
636
637 /**
638 * Returns a clone of this vector. The copy will contain a
639 * reference to a clone of the internal data array, not a reference
640 * to the original internal data array of this {@code Vector} object.
641 *
642 * @return a clone of this vector
643 */
644 public synchronized Object clone() {
645 try {
646 @SuppressWarnings("unchecked")
647 Vector<E> v = (Vector<E>) super.clone();
648 v.elementData = Arrays.copyOf(elementData, elementCount);
649 v.modCount = 0;
650 return v;
651 } catch (CloneNotSupportedException e) {
652 // this shouldn't happen, since we are Cloneable
653 throw new InternalError();
654 }
655 }
656
657 /**
658 * Returns an array containing all of the elements in this Vector
659 * in the correct order.
660 *
661 * @since 1.2
662 */
663 public synchronized Object[] toArray() {
664 return Arrays.copyOf(elementData, elementCount);
665 }
666
667 /**
668 * Returns an array containing all of the elements in this Vector in the
669 * correct order; the runtime type of the returned array is that of the
670 * specified array. If the Vector fits in the specified array, it is
671 * returned therein. Otherwise, a new array is allocated with the runtime
672 * type of the specified array and the size of this Vector.
673 *
674 * <p>If the Vector fits in the specified array with room to spare
675 * (i.e., the array has more elements than the Vector),
676 * the element in the array immediately following the end of the
677 * Vector is set to null. (This is useful in determining the length
678 * of the Vector <em>only</em> if the caller knows that the Vector
679 * does not contain any null elements.)
680 *
681 * @param a the array into which the elements of the Vector are to
682 * be stored, if it is big enough; otherwise, a new array of the
683 * same runtime type is allocated for this purpose.
684 * @return an array containing the elements of the Vector
685 * @throws ArrayStoreException if the runtime type of a is not a supertype
686 * of the runtime type of every element in this Vector
687 * @throws NullPointerException if the given array is null
688 * @since 1.2
689 */
690 @SuppressWarnings("unchecked")
691 public synchronized <T> T[] toArray(T[] a) {
692 if (a.length < elementCount)
693 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());
694
695 System.arraycopy(elementData, 0, a, 0, elementCount);
696
697 if (a.length > elementCount)
698 a[elementCount] = null;
699
700 return a;
701 }
702
703 // Positional Access Operations
704
705 @SuppressWarnings("unchecked")
706 E elementData(int index) {
707 return (E) elementData[index];
708 }
709
710 /**
711 * Returns the element at the specified position in this Vector.
712 *
713 * @param index index of the element to return
714 * @return object at the specified index
715 * @throws ArrayIndexOutOfBoundsException if the index is out of range
716 * ({@code index < 0 || index >= size()})
717 * @since 1.2
718 */
719 public synchronized E get(int index) {
720 if (index >= elementCount)
721 throw new ArrayIndexOutOfBoundsException(index);
722
723 return elementData(index);
724 }
725
726 /**
727 * Replaces the element at the specified position in this Vector with the
728 * specified element.
729 *
730 * @param index index of the element to replace
731 * @param element element to be stored at the specified position
732 * @return the element previously at the specified position
733 * @throws ArrayIndexOutOfBoundsException if the index is out of range
734 * ({@code index < 0 || index >= size()})
735 * @since 1.2
736 */
737 public synchronized E set(int index, E element) {
738 if (index >= elementCount)
739 throw new ArrayIndexOutOfBoundsException(index);
740
741 E oldValue = elementData(index);
742 elementData[index] = element;
743 return oldValue;
744 }
745
746 /**
747 * Appends the specified element to the end of this Vector.
748 *
749 * @param e element to be appended to this Vector
750 * @return {@code true} (as specified by {@link Collection#add})
751 * @since 1.2
752 */
753 public synchronized boolean add(E e) {
754 modCount++;
755 ensureCapacityHelper(elementCount + 1);
756 elementData[elementCount++] = e;
757 return true;
758 }
759
760 /**
761 * Removes the first occurrence of the specified element in this Vector
762 * If the Vector does not contain the element, it is unchanged. More
763 * formally, removes the element with the lowest index i such that
764 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such
765 * an element exists).
766 *
767 * @param o element to be removed from this Vector, if present
768 * @return true if the Vector contained the specified element
769 * @since 1.2
770 */
771 public boolean remove(Object o) {
772 return removeElement(o);
773 }
774
775 /**
776 * Inserts the specified element at the specified position in this Vector.
777 * Shifts the element currently at that position (if any) and any
778 * subsequent elements to the right (adds one to their indices).
779 *
780 * @param index index at which the specified element is to be inserted
781 * @param element element to be inserted
782 * @throws ArrayIndexOutOfBoundsException if the index is out of range
783 * ({@code index < 0 || index > size()})
784 * @since 1.2
785 */
786 public void add(int index, E element) {
787 insertElementAt(element, index);
788 }
789
790 /**
791 * Removes the element at the specified position in this Vector.
792 * Shifts any subsequent elements to the left (subtracts one from their
793 * indices). Returns the element that was removed from the Vector.
794 *
795 * @throws ArrayIndexOutOfBoundsException if the index is out of range
796 * ({@code index < 0 || index >= size()})
797 * @param index the index of the element to be removed
798 * @return element that was removed
799 * @since 1.2
800 */
801 public synchronized E remove(int index) {
802 modCount++;
803 if (index >= elementCount)
804 throw new ArrayIndexOutOfBoundsException(index);
805 E oldValue = elementData(index);
806
807 int numMoved = elementCount - index - 1;
808 if (numMoved > 0)
809 System.arraycopy(elementData, index+1, elementData, index,
810 numMoved);
811 elementData[--elementCount] = null; // Let gc do its work
812
813 return oldValue;
814 }
815
816 /**
817 * Removes all of the elements from this Vector. The Vector will
818 * be empty after this call returns (unless it throws an exception).
819 *
820 * @since 1.2
821 */
822 public void clear() {
823 removeAllElements();
824 }
825
826 // Bulk Operations
827
828 /**
829 * Returns true if this Vector contains all of the elements in the
830 * specified Collection.
831 *
832 * @param c a collection whose elements will be tested for containment
833 * in this Vector
834 * @return true if this Vector contains all of the elements in the
835 * specified collection
836 * @throws NullPointerException if the specified collection is null
837 */
838 public synchronized boolean containsAll(Collection<?> c) {
839 return super.containsAll(c);
840 }
841
842 /**
843 * Appends all of the elements in the specified Collection to the end of
844 * this Vector, in the order that they are returned by the specified
845 * Collection's Iterator. The behavior of this operation is undefined if
846 * the specified Collection is modified while the operation is in progress.
847 * (This implies that the behavior of this call is undefined if the
848 * specified Collection is this Vector, and this Vector is nonempty.)
849 *
850 * @param c elements to be inserted into this Vector
851 * @return {@code true} if this Vector changed as a result of the call
852 * @throws NullPointerException if the specified collection is null
853 * @since 1.2
854 */
855 public synchronized boolean addAll(Collection<? extends E> c) {
856 modCount++;
857 Object[] a = c.toArray();
858 int numNew = a.length;
859 ensureCapacityHelper(elementCount + numNew);
860 System.arraycopy(a, 0, elementData, elementCount, numNew);
861 elementCount += numNew;
862 return numNew != 0;
863 }
864
865 /**
866 * Removes from this Vector all of its elements that are contained in the
867 * specified Collection.
868 *
869 * @param c a collection of elements to be removed from the Vector
870 * @return true if this Vector changed as a result of the call
871 * @throws ClassCastException if the types of one or more elements
872 * in this vector are incompatible with the specified
873 * collection (optional)
874 * @throws NullPointerException if this vector contains one or more null
875 * elements and the specified collection does not support null
876 * elements (optional), or if the specified collection is null
877 * @since 1.2
878 */
879 public synchronized boolean removeAll(Collection<?> c) {
880 return super.removeAll(c);
881 }
882
883 /**
884 * Retains only the elements in this Vector that are contained in the
885 * specified Collection. In other words, removes from this Vector all
886 * of its elements that are not contained in the specified Collection.
887 *
888 * @param c a collection of elements to be retained in this Vector
889 * (all other elements are removed)
890 * @return true if this Vector changed as a result of the call
891 * @throws ClassCastException if the types of one or more elements
892 * in this vector are incompatible with the specified
893 * collection (optional)
894 * @throws NullPointerException if this vector contains one or more null
895 * elements and the specified collection does not support null
896 * elements (optional), or if the specified collection is null
897 * @since 1.2
898 */
899 public synchronized boolean retainAll(Collection<?> c) {
900 return super.retainAll(c);
901 }
902
903 /**
904 * Inserts all of the elements in the specified Collection into this
905 * Vector at the specified position. Shifts the element currently at
906 * that position (if any) and any subsequent elements to the right
907 * (increases their indices). The new elements will appear in the Vector
908 * in the order that they are returned by the specified Collection's
909 * iterator.
910 *
911 * @param index index at which to insert the first element from the
912 * specified collection
913 * @param c elements to be inserted into this Vector
914 * @return {@code true} if this Vector changed as a result of the call
915 * @throws ArrayIndexOutOfBoundsException if the index is out of range
916 * ({@code index < 0 || index > size()})
917 * @throws NullPointerException if the specified collection is null
918 * @since 1.2
919 */
920 public synchronized boolean addAll(int index, Collection<? extends E> c) {
921 modCount++;
922 if (index < 0 || index > elementCount)
923 throw new ArrayIndexOutOfBoundsException(index);
924
925 Object[] a = c.toArray();
926 int numNew = a.length;
927 ensureCapacityHelper(elementCount + numNew);
928
929 int numMoved = elementCount - index;
930 if (numMoved > 0)
931 System.arraycopy(elementData, index, elementData, index + numNew,
932 numMoved);
933
934 System.arraycopy(a, 0, elementData, index, numNew);
935 elementCount += numNew;
936 return numNew != 0;
937 }
938
939 /**
940 * Compares the specified Object with this Vector for equality. Returns
941 * true if and only if the specified Object is also a List, both Lists
942 * have the same size, and all corresponding pairs of elements in the two
943 * Lists are <em>equal</em>. (Two elements {@code e1} and
944 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null :
945 * e1.equals(e2))}.) In other words, two Lists are defined to be
946 * equal if they contain the same elements in the same order.
947 *
948 * @param o the Object to be compared for equality with this Vector
949 * @return true if the specified Object is equal to this Vector
950 */
951 public synchronized boolean equals(Object o) {
952 return super.equals(o);
953 }
954
955 /**
956 * Returns the hash code value for this Vector.
957 */
958 public synchronized int hashCode() {
959 return super.hashCode();
960 }
961
962 /**
963 * Returns a string representation of this Vector, containing
964 * the String representation of each element.
965 */
966 public synchronized String toString() {
967 return super.toString();
968 }
969
970 /**
971 * Returns a view of the portion of this List between fromIndex,
972 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are
973 * equal, the returned List is empty.) The returned List is backed by this
974 * List, so changes in the returned List are reflected in this List, and
975 * vice-versa. The returned List supports all of the optional List
976 * operations supported by this List.
977 *
978 * <p>This method eliminates the need for explicit range operations (of
979 * the sort that commonly exist for arrays). Any operation that expects
980 * a List can be used as a range operation by operating on a subList view
981 * instead of a whole List. For example, the following idiom
982 * removes a range of elements from a List:
983 * <pre>
984 * list.subList(from, to).clear();
985 * </pre>
986 * Similar idioms may be constructed for indexOf and lastIndexOf,
987 * and all of the algorithms in the Collections class can be applied to
988 * a subList.
989 *
990 * <p>The semantics of the List returned by this method become undefined if
991 * the backing list (i.e., this List) is <i>structurally modified</i> in
992 * any way other than via the returned List. (Structural modifications are
993 * those that change the size of the List, or otherwise perturb it in such
994 * a fashion that iterations in progress may yield incorrect results.)
995 *
996 * @param fromIndex low endpoint (inclusive) of the subList
997 * @param toIndex high endpoint (exclusive) of the subList
998 * @return a view of the specified range within this List
999 * @throws IndexOutOfBoundsException if an endpoint index value is out of range
1000 * {@code (fromIndex < 0 || toIndex > size)}
1001 * @throws IllegalArgumentException if the endpoint indices are out of order
1002 * {@code (fromIndex > toIndex)}
1003 */
1004 public synchronized List<E> subList(int fromIndex, int toIndex) {
1005 return Collections.synchronizedList(super.subList(fromIndex, toIndex),
1006 this);
1007 }
1008
1009 /**
1010 * Removes from this list all of the elements whose index is between
1011 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
1012 * Shifts any succeeding elements to the left (reduces their index).
1013 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
1014 * (If {@code toIndex==fromIndex}, this operation has no effect.)
1015 */
1016 protected synchronized void removeRange(int fromIndex, int toIndex) {
1017 modCount++;
1018 int numMoved = elementCount - toIndex;
1019 System.arraycopy(elementData, toIndex, elementData, fromIndex,
1020 numMoved);
1021
1022 // Let gc do its work
1023 int newElementCount = elementCount - (toIndex-fromIndex);
1024 while (elementCount != newElementCount)
1025 elementData[--elementCount] = null;
1026 }
1027
1028 /**
1029 * Save the state of the {@code Vector} instance to a stream (that
1030 * is, serialize it). This method is present merely for synchronization.
1031 * It just calls the default writeObject method.
1032 */
1033 private synchronized void writeObject(java.io.ObjectOutputStream s)
1034 throws java.io.IOException
1035 {
1036 s.defaultWriteObject();
1037 }
1038
1039 /**
1040 * Returns a list iterator over the elements in this list (in proper
1041 * sequence), starting at the specified position in the list.
1042 * The specified index indicates the first element that would be
1043 * returned by an initial call to {@link ListIterator#next next}.
1044 * An initial call to {@link ListIterator#previous previous} would
1045 * return the element with the specified index minus one.
1046 *
1047 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1048 *
1049 * @throws IndexOutOfBoundsException {@inheritDoc}
1050 */
1051 public synchronized ListIterator<E> listIterator(int index) {
1052 if (index < 0 || index > elementCount)
1053 throw new IndexOutOfBoundsException("Index: "+index);
1054 return new ListItr(index);
1055 }
1056
1057 /**
1058 * Returns a list iterator over the elements in this list (in proper
1059 * sequence).
1060 *
1061 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1062 *
1063 * @see #listIterator(int)
1064 */
1065 public synchronized ListIterator<E> listIterator() {
1066 return new ListItr(0);
1067 }
1068
1069 /**
1070 * Returns an iterator over the elements in this list in proper sequence.
1071 *
1072 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1073 *
1074 * @return an iterator over the elements in this list in proper sequence
1075 */
1076 public synchronized Iterator<E> iterator() {
1077 return new Itr();
1078 }
1079
1080 /**
1081 * An optimized version of AbstractList.Itr
1082 */
1083 private class Itr implements Iterator<E> {
1084 int cursor; // index of next element to return
1085 int lastRet = -1; // index of last element returned; -1 if no such
1086 int expectedModCount = modCount;
1087
1088 public boolean hasNext() {
1089 // Racy but within spec, since modifications are checked
1090 // within or after synchronization in next/previous
1091 return cursor != elementCount;
1092 }
1093
1094 public E next() {
1095 synchronized (Vector.this) {
1096 checkForComodification();
1097 int i = cursor;
1098 if (i >= elementCount)
1099 throw new NoSuchElementException();
1100 cursor = i + 1;
1101 return elementData(lastRet = i);
1102 }
1103 }
1104
1105 public void remove() {
1106 if (lastRet == -1)
1107 throw new IllegalStateException();
1108 synchronized (Vector.this) {
1109 checkForComodification();
1110 Vector.this.remove(lastRet);
1111 expectedModCount = modCount;
1112 }
1113 cursor = lastRet;
1114 lastRet = -1;
1115 }
1116
1117 final void checkForComodification() {
1118 if (modCount != expectedModCount)
1119 throw new ConcurrentModificationException();
1120 }
1121 }
1122
1123 /**
1124 * An optimized version of AbstractList.ListItr
1125 */
1126 final class ListItr extends Itr implements ListIterator<E> {
1127 ListItr(int index) {
1128 super();
1129 cursor = index;
1130 }
1131
1132 public boolean hasPrevious() {
1133 return cursor != 0;
1134 }
1135
1136 public int nextIndex() {
1137 return cursor;
1138 }
1139
1140 public int previousIndex() {
1141 return cursor - 1;
1142 }
1143
1144 public E previous() {
1145 synchronized (Vector.this) {
1146 checkForComodification();
1147 int i = cursor - 1;
1148 if (i < 0)
1149 throw new NoSuchElementException();
1150 cursor = i;
1151 return elementData(lastRet = i);
1152 }
1153 }
1154
1155 public void set(E e) {
1156 if (lastRet == -1)
1157 throw new IllegalStateException();
1158 synchronized (Vector.this) {
1159 checkForComodification();
1160 Vector.this.set(lastRet, e);
1161 }
1162 }
1163
1164 public void add(E e) {
1165 int i = cursor;
1166 synchronized (Vector.this) {
1167 checkForComodification();
1168 Vector.this.add(i, e);
1169 expectedModCount = modCount;
1170 }
1171 cursor = i + 1;
1172 lastRet = -1;
1173 }
1174 }
1175 }
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