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
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20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 * questions.
24 */
25
26 package java.util;
27
28 import java.util.function.Consumer;
29 import java.util.function.Predicate;
30 import java.util.function.UnaryOperator;
31
32 /**
33 * The {@code Vector} class implements a growable array of
34 * objects. Like an array, it contains components that can be
35 * accessed using an integer index. However, the size of a
36 * {@code Vector} can grow or shrink as needed to accommodate
37 * adding and removing items after the {@code Vector} has been created.
38 *
39 * <p>Each vector tries to optimize storage management by maintaining a
40 * {@code capacity} and a {@code capacityIncrement}. The
41 * {@code capacity} is always at least as large as the vector
42 * size; it is usually larger because as components are added to the
43 * vector, the vector's storage increases in chunks the size of
44 * {@code capacityIncrement}. An application can increase the
45 * capacity of a vector before inserting a large number of
46 * components; this reduces the amount of incremental reallocation.
47 *
48 * <p id="fail-fast">
49 * The iterators returned by this class's {@link #iterator() iterator} and
50 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:
51 * if the vector is structurally modified at any time after the iterator is
52 * created, in any way except through the iterator's own
53 * {@link ListIterator#remove() remove} or
54 * {@link ListIterator#add(Object) add} methods, the iterator will throw a
55 * {@link ConcurrentModificationException}. Thus, in the face of
56 * concurrent modification, the iterator fails quickly and cleanly, rather
57 * than risking arbitrary, non-deterministic behavior at an undetermined
58 * time in the future. The {@link Enumeration Enumerations} returned by
59 * the {@link #elements() elements} method are <em>not</em> fail-fast; if the
60 * Vector is structurally modified at any time after the enumeration is
61 * created then the results of enumerating are undefined.
62 *
63 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
64 * as it is, generally speaking, impossible to make any hard guarantees in the
65 * presence of unsynchronized concurrent modification. Fail-fast iterators
66 * throw {@code ConcurrentModificationException} on a best-effort basis.
67 * Therefore, it would be wrong to write a program that depended on this
68 * exception for its correctness: <i>the fail-fast behavior of iterators
69 * should be used only to detect bugs.</i>
70 *
71 * <p>As of the Java 2 platform v1.2, this class was retrofitted to
72 * implement the {@link List} interface, making it a member of the
73 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
74 * Java Collections Framework</a>. Unlike the new collection
75 * implementations, {@code Vector} is synchronized. If a thread-safe
76 * implementation is not needed, it is recommended to use {@link
77 * ArrayList} in place of {@code Vector}.
78 *
79 * @param <E> Type of component elements
80 *
81 * @author Lee Boynton
82 * @author Jonathan Payne
83 * @see Collection
84 * @see LinkedList
85 * @since 1.0
86 */
87 public class Vector<E>
88 extends AbstractList<E>
89 implements List<E>, RandomAccess, Cloneable, java.io.Serializable
90 {
91 /**
92 * The array buffer into which the components of the vector are
93 * stored. The capacity of the vector is the length of this array buffer,
94 * and is at least large enough to contain all the vector's elements.
95 *
96 * <p>Any array elements following the last element in the Vector are null.
97 *
98 * @serial
99 */
100 protected Object[] elementData;
101
102 /**
103 * The number of valid components in this {@code Vector} object.
104 * Components {@code elementData[0]} through
105 * {@code elementData[elementCount-1]} are the actual items.
106 *
107 * @serial
108 */
109 protected int elementCount;
110
111 /**
112 * The amount by which the capacity of the vector is automatically
113 * incremented when its size becomes greater than its capacity. If
114 * the capacity increment is less than or equal to zero, the capacity
115 * of the vector is doubled each time it needs to grow.
116 *
117 * @serial
118 */
119 protected int capacityIncrement;
120
121 /** use serialVersionUID from JDK 1.0.2 for interoperability */
122 private static final long serialVersionUID = -2767605614048989439L;
123
124 /**
125 * Constructs an empty vector with the specified initial capacity and
126 * capacity increment.
127 *
128 * @param initialCapacity the initial capacity of the vector
129 * @param capacityIncrement the amount by which the capacity is
130 * increased when the vector overflows
131 * @throws IllegalArgumentException if the specified initial capacity
132 * is negative
133 */
134 public Vector(int initialCapacity, int capacityIncrement) {
135 super();
136 if (initialCapacity < 0)
137 throw new IllegalArgumentException("Illegal Capacity: "+
138 initialCapacity);
139 this.elementData = new Object[initialCapacity];
140 this.capacityIncrement = capacityIncrement;
141 }
142
143 /**
144 * Constructs an empty vector with the specified initial capacity and
145 * with its capacity increment equal to zero.
146 *
147 * @param initialCapacity the initial capacity of the vector
148 * @throws IllegalArgumentException if the specified initial capacity
149 * is negative
150 */
151 public Vector(int initialCapacity) {
152 this(initialCapacity, 0);
153 }
154
155 /**
156 * Constructs an empty vector so that its internal data array
157 * has size {@code 10} and its standard capacity increment is
158 * zero.
159 */
160 public Vector() {
161 this(10);
162 }
163
164 /**
165 * Constructs a vector containing the elements of the specified
166 * collection, in the order they are returned by the collection's
167 * iterator.
168 *
169 * @param c the collection whose elements are to be placed into this
170 * vector
171 * @throws NullPointerException if the specified collection is null
172 * @since 1.2
173 */
174 public Vector(Collection<? extends E> c) {
175 elementData = c.toArray();
176 elementCount = elementData.length;
177 // c.toArray might (incorrectly) not return Object[] (see 6260652)
178 if (elementData.getClass() != Object[].class)
179 elementData = Arrays.copyOf(elementData, elementCount, Object[].class);
180 }
181
182 /**
183 * Copies the components of this vector into the specified array.
184 * The item at index {@code k} in this vector is copied into
185 * component {@code k} of {@code anArray}.
186 *
187 * @param anArray the array into which the components get copied
188 * @throws NullPointerException if the given array is null
189 * @throws IndexOutOfBoundsException if the specified array is not
190 * large enough to hold all the components of this vector
191 * @throws ArrayStoreException if a component of this vector is not of
192 * a runtime type that can be stored in the specified array
193 * @see #toArray(Object[])
194 */
195 public synchronized void copyInto(Object[] anArray) {
196 System.arraycopy(elementData, 0, anArray, 0, elementCount);
197 }
198
199 /**
200 * Trims the capacity of this vector to be the vector's current
201 * size. If the capacity of this vector is larger than its current
202 * size, then the capacity is changed to equal the size by replacing
203 * its internal data array, kept in the field {@code elementData},
204 * with a smaller one. An application can use this operation to
205 * minimize the storage of a vector.
206 */
207 public synchronized void trimToSize() {
208 modCount++;
209 int oldCapacity = elementData.length;
210 if (elementCount < oldCapacity) {
211 elementData = Arrays.copyOf(elementData, elementCount);
212 }
213 }
214
215 /**
216 * Increases the capacity of this vector, if necessary, to ensure
217 * that it can hold at least the number of components specified by
218 * the minimum capacity argument.
219 *
220 * <p>If the current capacity of this vector is less than
221 * {@code minCapacity}, then its capacity is increased by replacing its
222 * internal data array, kept in the field {@code elementData}, with a
223 * larger one. The size of the new data array will be the old size plus
224 * {@code capacityIncrement}, unless the value of
225 * {@code capacityIncrement} is less than or equal to zero, in which case
226 * the new capacity will be twice the old capacity; but if this new size
227 * is still smaller than {@code minCapacity}, then the new capacity will
228 * be {@code minCapacity}.
229 *
230 * @param minCapacity the desired minimum capacity
231 */
232 public synchronized void ensureCapacity(int minCapacity) {
233 if (minCapacity > 0) {
234 modCount++;
235 ensureCapacityHelper(minCapacity);
236 }
237 }
238
239 /**
240 * This implements the unsynchronized semantics of ensureCapacity.
241 * Synchronized methods in this class can internally call this
242 * method for ensuring capacity without incurring the cost of an
243 * extra synchronization.
244 *
245 * @see #ensureCapacity(int)
246 */
247 private void ensureCapacityHelper(int minCapacity) {
248 // overflow-conscious code
249 if (minCapacity - elementData.length > 0)
250 grow(minCapacity);
251 }
252
253 /**
254 * The maximum size of array to allocate.
255 * Some VMs reserve some header words in an array.
256 * Attempts to allocate larger arrays may result in
257 * OutOfMemoryError: Requested array size exceeds VM limit
258 */
259 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
260
261 private void grow(int minCapacity) {
262 // overflow-conscious code
263 int oldCapacity = elementData.length;
264 int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
265 capacityIncrement : oldCapacity);
266 if (newCapacity - minCapacity < 0)
267 newCapacity = minCapacity;
268 if (newCapacity - MAX_ARRAY_SIZE > 0)
269 newCapacity = hugeCapacity(minCapacity);
270 elementData = Arrays.copyOf(elementData, newCapacity);
271 }
272
273 private static int hugeCapacity(int minCapacity) {
274 if (minCapacity < 0) // overflow
275 throw new OutOfMemoryError();
276 return (minCapacity > MAX_ARRAY_SIZE) ?
277 Integer.MAX_VALUE :
278 MAX_ARRAY_SIZE;
279 }
280
281 /**
282 * Sets the size of this vector. If the new size is greater than the
283 * current size, new {@code null} items are added to the end of
284 * the vector. If the new size is less than the current size, all
285 * components at index {@code newSize} and greater are discarded.
286 *
287 * @param newSize the new size of this vector
288 * @throws ArrayIndexOutOfBoundsException if the new size is negative
289 */
290 public synchronized void setSize(int newSize) {
291 modCount++;
292 if (newSize > elementCount) {
293 ensureCapacityHelper(newSize);
294 } else {
295 for (int i = newSize ; i < elementCount ; i++) {
296 elementData[i] = null;
297 }
298 }
299 elementCount = newSize;
300 }
301
302 /**
303 * Returns the current capacity of this vector.
304 *
305 * @return the current capacity (the length of its internal
306 * data array, kept in the field {@code elementData}
307 * of this vector)
308 */
309 public synchronized int capacity() {
310 return elementData.length;
311 }
312
313 /**
314 * Returns the number of components in this vector.
315 *
316 * @return the number of components in this vector
317 */
318 public synchronized int size() {
319 return elementCount;
320 }
321
322 /**
323 * Tests if this vector has no components.
324 *
325 * @return {@code true} if and only if this vector has
326 * no components, that is, its size is zero;
327 * {@code false} otherwise.
328 */
329 public synchronized boolean isEmpty() {
330 return elementCount == 0;
331 }
332
333 /**
334 * Returns an enumeration of the components of this vector. The
335 * returned {@code Enumeration} object will generate all items in
336 * this vector. The first item generated is the item at index {@code 0},
337 * then the item at index {@code 1}, and so on. If the vector is
338 * structurally modified while enumerating over the elements then the
339 * results of enumerating are undefined.
340 *
341 * @return an enumeration of the components of this vector
342 * @see Iterator
343 */
344 public Enumeration<E> elements() {
345 return new Enumeration<E>() {
346 int count = 0;
347
348 public boolean hasMoreElements() {
349 return count < elementCount;
350 }
351
352 public E nextElement() {
353 synchronized (Vector.this) {
354 if (count < elementCount) {
355 return elementData(count++);
356 }
357 }
358 throw new NoSuchElementException("Vector Enumeration");
359 }
360 };
361 }
362
363 /**
364 * Returns {@code true} if this vector contains the specified element.
365 * More formally, returns {@code true} if and only if this vector
366 * contains at least one element {@code e} such that
367 * <tt>(o==null ? e==null : o.equals(e))</tt>.
368 *
369 * @param o element whose presence in this vector is to be tested
370 * @return {@code true} if this vector contains the specified element
371 */
372 public boolean contains(Object o) {
373 return indexOf(o, 0) >= 0;
374 }
375
376 /**
377 * Returns the index of the first occurrence of the specified element
378 * in this vector, or -1 if this vector does not contain the element.
379 * More formally, returns the lowest index {@code i} such that
380 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
381 * or -1 if there is no such index.
382 *
383 * @param o element to search for
384 * @return the index of the first occurrence of the specified element in
385 * this vector, or -1 if this vector does not contain the element
386 */
387 public int indexOf(Object o) {
388 return indexOf(o, 0);
389 }
390
391 /**
392 * Returns the index of the first occurrence of the specified element in
393 * this vector, searching forwards from {@code index}, or returns -1 if
394 * the element is not found.
395 * More formally, returns the lowest index {@code i} such that
396 * <tt>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
397 * or -1 if there is no such index.
398 *
399 * @param o element to search for
400 * @param index index to start searching from
401 * @return the index of the first occurrence of the element in
402 * this vector at position {@code index} or later in the vector;
403 * {@code -1} if the element is not found.
404 * @throws IndexOutOfBoundsException if the specified index is negative
405 * @see Object#equals(Object)
406 */
407 public synchronized int indexOf(Object o, int index) {
408 if (o == null) {
409 for (int i = index ; i < elementCount ; i++)
410 if (elementData[i]==null)
411 return i;
412 } else {
413 for (int i = index ; i < elementCount ; i++)
414 if (o.equals(elementData[i]))
415 return i;
416 }
417 return -1;
418 }
419
420 /**
421 * Returns the index of the last occurrence of the specified element
422 * in this vector, or -1 if this vector does not contain the element.
423 * More formally, returns the highest index {@code i} such that
424 * <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>,
425 * or -1 if there is no such index.
426 *
427 * @param o element to search for
428 * @return the index of the last occurrence of the specified element in
429 * this vector, or -1 if this vector does not contain the element
430 */
431 public synchronized int lastIndexOf(Object o) {
432 return lastIndexOf(o, elementCount-1);
433 }
434
435 /**
436 * Returns the index of the last occurrence of the specified element in
437 * this vector, searching backwards from {@code index}, or returns -1 if
438 * the element is not found.
439 * More formally, returns the highest index {@code i} such that
440 * <tt>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</tt>,
441 * or -1 if there is no such index.
442 *
443 * @param o element to search for
444 * @param index index to start searching backwards from
445 * @return the index of the last occurrence of the element at position
446 * less than or equal to {@code index} in this vector;
447 * -1 if the element is not found.
448 * @throws IndexOutOfBoundsException if the specified index is greater
449 * than or equal to the current size of this vector
450 */
451 public synchronized int lastIndexOf(Object o, int index) {
452 if (index >= elementCount)
453 throw new IndexOutOfBoundsException(index + " >= "+ elementCount);
454
455 if (o == null) {
456 for (int i = index; i >= 0; i--)
457 if (elementData[i]==null)
458 return i;
459 } else {
460 for (int i = index; i >= 0; i--)
461 if (o.equals(elementData[i]))
462 return i;
463 }
464 return -1;
465 }
466
467 /**
468 * Returns the component at the specified index.
469 *
470 * <p>This method is identical in functionality to the {@link #get(int)}
471 * method (which is part of the {@link List} interface).
472 *
473 * @param index an index into this vector
474 * @return the component at the specified index
475 * @throws ArrayIndexOutOfBoundsException if the index is out of range
476 * ({@code index < 0 || index >= size()})
477 */
478 public synchronized E elementAt(int index) {
479 if (index >= elementCount) {
480 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
481 }
482
483 return elementData(index);
484 }
485
486 /**
487 * Returns the first component (the item at index {@code 0}) of
488 * this vector.
489 *
490 * @return the first component of this vector
491 * @throws NoSuchElementException if this vector has no components
492 */
493 public synchronized E firstElement() {
494 if (elementCount == 0) {
495 throw new NoSuchElementException();
496 }
497 return elementData(0);
498 }
499
500 /**
501 * Returns the last component of the vector.
502 *
503 * @return the last component of the vector, i.e., the component at index
504 * <code>size() - 1</code>.
505 * @throws NoSuchElementException if this vector is empty
506 */
507 public synchronized E lastElement() {
508 if (elementCount == 0) {
509 throw new NoSuchElementException();
510 }
511 return elementData(elementCount - 1);
512 }
513
514 /**
515 * Sets the component at the specified {@code index} of this
516 * vector to be the specified object. The previous component at that
517 * position is discarded.
518 *
519 * <p>The index must be a value greater than or equal to {@code 0}
520 * and less than the current size of the vector.
521 *
522 * <p>This method is identical in functionality to the
523 * {@link #set(int, Object) set(int, E)}
524 * method (which is part of the {@link List} interface). Note that the
525 * {@code set} method reverses the order of the parameters, to more closely
526 * match array usage. Note also that the {@code set} method returns the
527 * old value that was stored at the specified position.
528 *
529 * @param obj what the component is to be set to
530 * @param index the specified index
531 * @throws ArrayIndexOutOfBoundsException if the index is out of range
532 * ({@code index < 0 || index >= size()})
533 */
534 public synchronized void setElementAt(E obj, int index) {
535 if (index >= elementCount) {
536 throw new ArrayIndexOutOfBoundsException(index + " >= " +
537 elementCount);
538 }
539 elementData[index] = obj;
540 }
541
542 /**
543 * Deletes the component at the specified index. Each component in
544 * this vector with an index greater or equal to the specified
545 * {@code index} is shifted downward to have an index one
546 * smaller than the value it had previously. The size of this vector
547 * is decreased by {@code 1}.
548 *
549 * <p>The index must be a value greater than or equal to {@code 0}
550 * and less than the current size of the vector.
551 *
552 * <p>This method is identical in functionality to the {@link #remove(int)}
553 * method (which is part of the {@link List} interface). Note that the
554 * {@code remove} method returns the old value that was stored at the
555 * specified position.
556 *
557 * @param index the index of the object to remove
558 * @throws ArrayIndexOutOfBoundsException if the index is out of range
559 * ({@code index < 0 || index >= size()})
560 */
561 public synchronized void removeElementAt(int index) {
562 if (index >= elementCount) {
563 throw new ArrayIndexOutOfBoundsException(index + " >= " +
564 elementCount);
565 }
566 else if (index < 0) {
567 throw new ArrayIndexOutOfBoundsException(index);
568 }
569 int j = elementCount - index - 1;
570 if (j > 0) {
571 System.arraycopy(elementData, index + 1, elementData, index, j);
572 }
573 modCount++;
574 elementCount--;
575 elementData[elementCount] = null; /* to let gc do its work */
576 }
577
578 /**
579 * Inserts the specified object as a component in this vector at the
580 * specified {@code index}. Each component in this vector with
581 * an index greater or equal to the specified {@code index} is
582 * shifted upward to have an index one greater than the value it had
583 * previously.
584 *
585 * <p>The index must be a value greater than or equal to {@code 0}
586 * and less than or equal to the current size of the vector. (If the
587 * index is equal to the current size of the vector, the new element
588 * is appended to the Vector.)
589 *
590 * <p>This method is identical in functionality to the
591 * {@link #add(int, Object) add(int, E)}
592 * method (which is part of the {@link List} interface). Note that the
593 * {@code add} method reverses the order of the parameters, to more closely
594 * match array usage.
595 *
596 * @param obj the component to insert
597 * @param index where to insert the new component
598 * @throws ArrayIndexOutOfBoundsException if the index is out of range
599 * ({@code index < 0 || index > size()})
600 */
601 public synchronized void insertElementAt(E obj, int index) {
602 if (index > elementCount) {
603 throw new ArrayIndexOutOfBoundsException(index
604 + " > " + elementCount);
605 }
606 ensureCapacityHelper(elementCount + 1);
607 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
608 elementData[index] = obj;
609 modCount++;
610 elementCount++;
611 }
612
613 /**
614 * Adds the specified component to the end of this vector,
615 * increasing its size by one. The capacity of this vector is
616 * increased if its size becomes greater than its capacity.
617 *
618 * <p>This method is identical in functionality to the
619 * {@link #add(Object) add(E)}
620 * method (which is part of the {@link List} interface).
621 *
622 * @param obj the component to be added
623 */
624 public synchronized void addElement(E obj) {
625 ensureCapacityHelper(elementCount + 1);
626 modCount++;
627 elementData[elementCount++] = obj;
628 }
629
630 /**
631 * Removes the first (lowest-indexed) occurrence of the argument
632 * from this vector. If the object is found in this vector, each
633 * component in the vector with an index greater or equal to the
634 * object's index is shifted downward to have an index one smaller
635 * than the value it had previously.
636 *
637 * <p>This method is identical in functionality to the
638 * {@link #remove(Object)} method (which is part of the
639 * {@link List} interface).
640 *
641 * @param obj the component to be removed
642 * @return {@code true} if the argument was a component of this
643 * vector; {@code false} otherwise.
644 */
645 public synchronized boolean removeElement(Object obj) {
646 modCount++;
647 int i = indexOf(obj);
648 if (i >= 0) {
649 removeElementAt(i);
650 return true;
651 }
652 return false;
653 }
654
655 /**
656 * Removes all components from this vector and sets its size to zero.
657 *
658 * <p>This method is identical in functionality to the {@link #clear}
659 * method (which is part of the {@link List} interface).
660 */
661 public synchronized void removeAllElements() {
662 // Let gc do its work
663 for (int i = 0; i < elementCount; i++)
664 elementData[i] = null;
665
666 modCount++;
667 elementCount = 0;
668 }
669
670 /**
671 * Returns a clone of this vector. The copy will contain a
672 * reference to a clone of the internal data array, not a reference
673 * to the original internal data array of this {@code Vector} object.
674 *
675 * @return a clone of this vector
676 */
677 public synchronized Object clone() {
678 try {
679 @SuppressWarnings("unchecked")
680 Vector<E> v = (Vector<E>) super.clone();
681 v.elementData = Arrays.copyOf(elementData, elementCount);
682 v.modCount = 0;
683 return v;
684 } catch (CloneNotSupportedException e) {
685 // this shouldn't happen, since we are Cloneable
686 throw new InternalError(e);
687 }
688 }
689
690 /**
691 * Returns an array containing all of the elements in this Vector
692 * in the correct order.
693 *
694 * @since 1.2
695 */
696 public synchronized Object[] toArray() {
697 return Arrays.copyOf(elementData, elementCount);
698 }
699
700 /**
701 * Returns an array containing all of the elements in this Vector in the
702 * correct order; the runtime type of the returned array is that of the
703 * specified array. If the Vector fits in the specified array, it is
704 * returned therein. Otherwise, a new array is allocated with the runtime
705 * type of the specified array and the size of this Vector.
706 *
707 * <p>If the Vector fits in the specified array with room to spare
708 * (i.e., the array has more elements than the Vector),
709 * the element in the array immediately following the end of the
710 * Vector is set to null. (This is useful in determining the length
711 * of the Vector <em>only</em> if the caller knows that the Vector
712 * does not contain any null elements.)
713 *
714 * @param <T> type of array elements. The same type as {@code <E>} or a
715 * supertype of {@code <E>}.
716 * @param a the array into which the elements of the Vector are to
717 * be stored, if it is big enough; otherwise, a new array of the
718 * same runtime type is allocated for this purpose.
719 * @return an array containing the elements of the Vector
720 * @throws ArrayStoreException if the runtime type of a, {@code <T>}, is not
721 * a supertype of the runtime type, {@code <E>}, of every element in this
722 * Vector
723 * @throws NullPointerException if the given array is null
724 * @since 1.2
725 */
726 @SuppressWarnings("unchecked")
727 public synchronized <T> T[] toArray(T[] a) {
728 if (a.length < elementCount)
729 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());
730
731 System.arraycopy(elementData, 0, a, 0, elementCount);
732
733 if (a.length > elementCount)
734 a[elementCount] = null;
735
736 return a;
737 }
738
739 // Positional Access Operations
740
741 @SuppressWarnings("unchecked")
742 E elementData(int index) {
743 return (E) elementData[index];
744 }
745
746 /**
747 * Returns the element at the specified position in this Vector.
748 *
749 * @param index index of the element to return
750 * @return object at the specified index
751 * @throws ArrayIndexOutOfBoundsException if the index is out of range
752 * ({@code index < 0 || index >= size()})
753 * @since 1.2
754 */
755 public synchronized E get(int index) {
756 if (index >= elementCount)
757 throw new ArrayIndexOutOfBoundsException(index);
758
759 return elementData(index);
760 }
761
762 /**
763 * Replaces the element at the specified position in this Vector with the
764 * specified element.
765 *
766 * @param index index of the element to replace
767 * @param element element to be stored at the specified position
768 * @return the element previously at the specified position
769 * @throws ArrayIndexOutOfBoundsException if the index is out of range
770 * ({@code index < 0 || index >= size()})
771 * @since 1.2
772 */
773 public synchronized E set(int index, E element) {
774 if (index >= elementCount)
775 throw new ArrayIndexOutOfBoundsException(index);
776
777 E oldValue = elementData(index);
778 elementData[index] = element;
779 return oldValue;
780 }
781
782 /**
783 * Appends the specified element to the end of this Vector.
784 *
785 * @param e element to be appended to this Vector
786 * @return {@code true} (as specified by {@link Collection#add})
787 * @since 1.2
788 */
789 public synchronized boolean add(E e) {
790 ensureCapacityHelper(elementCount + 1);
791 modCount++;
792 elementData[elementCount++] = e;
793 return true;
794 }
795
796 /**
797 * Removes the first occurrence of the specified element in this Vector
798 * If the Vector does not contain the element, it is unchanged. More
799 * formally, removes the element with the lowest index i such that
800 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such
801 * an element exists).
802 *
803 * @param o element to be removed from this Vector, if present
804 * @return true if the Vector contained the specified element
805 * @since 1.2
806 */
807 public boolean remove(Object o) {
808 return removeElement(o);
809 }
810
811 /**
812 * Inserts the specified element at the specified position in this Vector.
813 * Shifts the element currently at that position (if any) and any
814 * subsequent elements to the right (adds one to their indices).
815 *
816 * @param index index at which the specified element is to be inserted
817 * @param element element to be inserted
818 * @throws ArrayIndexOutOfBoundsException if the index is out of range
819 * ({@code index < 0 || index > size()})
820 * @since 1.2
821 */
822 public void add(int index, E element) {
823 insertElementAt(element, index);
824 }
825
826 /**
827 * Removes the element at the specified position in this Vector.
828 * Shifts any subsequent elements to the left (subtracts one from their
829 * indices). Returns the element that was removed from the Vector.
830 *
831 * @throws ArrayIndexOutOfBoundsException if the index is out of range
832 * ({@code index < 0 || index >= size()})
833 * @param index the index of the element to be removed
834 * @return element that was removed
835 * @since 1.2
836 */
837 public synchronized E remove(int index) {
838 modCount++;
839 if (index >= elementCount)
840 throw new ArrayIndexOutOfBoundsException(index);
841 E oldValue = elementData(index);
842
843 int numMoved = elementCount - index - 1;
844 if (numMoved > 0)
845 System.arraycopy(elementData, index+1, elementData, index,
846 numMoved);
847 elementData[--elementCount] = null; // Let gc do its work
848
849 return oldValue;
850 }
851
852 /**
853 * Removes all of the elements from this Vector. The Vector will
854 * be empty after this call returns (unless it throws an exception).
855 *
856 * @since 1.2
857 */
858 public void clear() {
859 removeAllElements();
860 }
861
862 // Bulk Operations
863
864 /**
865 * Returns true if this Vector contains all of the elements in the
866 * specified Collection.
867 *
868 * @param c a collection whose elements will be tested for containment
869 * in this Vector
870 * @return true if this Vector contains all of the elements in the
871 * specified collection
872 * @throws NullPointerException if the specified collection is null
873 */
874 public synchronized boolean containsAll(Collection<?> c) {
875 return super.containsAll(c);
876 }
877
878 /**
879 * Appends all of the elements in the specified Collection to the end of
880 * this Vector, in the order that they are returned by the specified
881 * Collection's Iterator. The behavior of this operation is undefined if
882 * the specified Collection is modified while the operation is in progress.
883 * (This implies that the behavior of this call is undefined if the
884 * specified Collection is this Vector, and this Vector is nonempty.)
885 *
886 * @param c elements to be inserted into this Vector
887 * @return {@code true} if this Vector changed as a result of the call
888 * @throws NullPointerException if the specified collection is null
889 * @since 1.2
890 */
891 public boolean addAll(Collection<? extends E> c) {
892 Object[] a = c.toArray();
893 int numNew = a.length;
894 if (numNew > 0) {
895 synchronized (this) {
896 ensureCapacityHelper(elementCount + numNew);
897 System.arraycopy(a, 0, elementData, elementCount, numNew);
898 modCount++;
899 elementCount += numNew;
900 }
901 }
902 return numNew > 0;
903 }
904
905 /**
906 * Removes from this Vector all of its elements that are contained in the
907 * specified Collection.
908 *
909 * @param c a collection of elements to be removed from the Vector
910 * @return true if this Vector changed as a result of the call
911 * @throws ClassCastException if the types of one or more elements
912 * in this vector are incompatible with the specified
913 * collection
914 * (<a href="Collection.html#optional-restrictions">optional</a>)
915 * @throws NullPointerException if this vector contains one or more null
916 * elements and the specified collection does not support null
917 * elements
918 * (<a href="Collection.html#optional-restrictions">optional</a>),
919 * or if the specified collection is null
920 * @since 1.2
921 */
922 public synchronized boolean removeAll(Collection<?> c) {
923 return super.removeAll(c);
924 }
925
926 /**
927 * Retains only the elements in this Vector that are contained in the
928 * specified Collection. In other words, removes from this Vector all
929 * of its elements that are not contained in the specified Collection.
930 *
931 * @param c a collection of elements to be retained in this Vector
932 * (all other elements are removed)
933 * @return true if this Vector changed as a result of the call
934 * @throws ClassCastException if the types of one or more elements
935 * in this vector are incompatible with the specified
936 * collection
937 * (<a href="Collection.html#optional-restrictions">optional</a>)
938 * @throws NullPointerException if this vector contains one or more null
939 * elements and the specified collection does not support null
940 * elements
941 * (<a href="Collection.html#optional-restrictions">optional</a>),
942 * or if the specified collection is null
943 * @since 1.2
944 */
945 public synchronized boolean retainAll(Collection<?> c) {
946 return super.retainAll(c);
947 }
948
949 /**
950 * Inserts all of the elements in the specified Collection into this
951 * Vector at the specified position. Shifts the element currently at
952 * that position (if any) and any subsequent elements to the right
953 * (increases their indices). The new elements will appear in the Vector
954 * in the order that they are returned by the specified Collection's
955 * iterator.
956 *
957 * @param index index at which to insert the first element from the
958 * specified collection
959 * @param c elements to be inserted into this Vector
960 * @return {@code true} if this Vector changed as a result of the call
961 * @throws ArrayIndexOutOfBoundsException if the index is out of range
962 * ({@code index < 0 || index > size()})
963 * @throws NullPointerException if the specified collection is null
964 * @since 1.2
965 */
966 public synchronized boolean addAll(int index, Collection<? extends E> c) {
967 if (index < 0 || index > elementCount)
968 throw new ArrayIndexOutOfBoundsException(index);
969
970 Object[] a = c.toArray();
971 int numNew = a.length;
972
973 if (numNew > 0) {
974 ensureCapacityHelper(elementCount + numNew);
975
976 int numMoved = elementCount - index;
977 if (numMoved > 0)
978 System.arraycopy(elementData, index, elementData,
979 index + numNew, numMoved);
980
981 System.arraycopy(a, 0, elementData, index, numNew);
982 elementCount += numNew;
983 modCount++;
984 }
985 return numNew > 0;
986 }
987
988 /**
989 * Compares the specified Object with this Vector for equality. Returns
990 * true if and only if the specified Object is also a List, both Lists
991 * have the same size, and all corresponding pairs of elements in the two
992 * Lists are <em>equal</em>. (Two elements {@code e1} and
993 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null :
994 * e1.equals(e2))}.) In other words, two Lists are defined to be
995 * equal if they contain the same elements in the same order.
996 *
997 * @param o the Object to be compared for equality with this Vector
998 * @return true if the specified Object is equal to this Vector
999 */
1000 public synchronized boolean equals(Object o) {
1001 return super.equals(o);
1002 }
1003
1004 /**
1005 * Returns the hash code value for this Vector.
1006 */
1007 public synchronized int hashCode() {
1008 return super.hashCode();
1009 }
1010
1011 /**
1012 * Returns a string representation of this Vector, containing
1013 * the String representation of each element.
1014 */
1015 public synchronized String toString() {
1016 return super.toString();
1017 }
1018
1019 /**
1020 * Returns a view of the portion of this List between fromIndex,
1021 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are
1022 * equal, the returned List is empty.) The returned List is backed by this
1023 * List, so changes in the returned List are reflected in this List, and
1024 * vice-versa. The returned List supports all of the optional List
1025 * operations supported by this List.
1026 *
1027 * <p>This method eliminates the need for explicit range operations (of
1028 * the sort that commonly exist for arrays). Any operation that expects
1029 * a List can be used as a range operation by operating on a subList view
1030 * instead of a whole List. For example, the following idiom
1031 * removes a range of elements from a List:
1032 * <pre>
1033 * list.subList(from, to).clear();
1034 * </pre>
1035 * Similar idioms may be constructed for indexOf and lastIndexOf,
1036 * and all of the algorithms in the Collections class can be applied to
1037 * a subList.
1038 *
1039 * <p>The semantics of the List returned by this method become undefined if
1040 * the backing list (i.e., this List) is <i>structurally modified</i> in
1041 * any way other than via the returned List. (Structural modifications are
1042 * those that change the size of the List, or otherwise perturb it in such
1043 * a fashion that iterations in progress may yield incorrect results.)
1044 *
1045 * @param fromIndex low endpoint (inclusive) of the subList
1046 * @param toIndex high endpoint (exclusive) of the subList
1047 * @return a view of the specified range within this List
1048 * @throws IndexOutOfBoundsException if an endpoint index value is out of range
1049 * {@code (fromIndex < 0 || toIndex > size)}
1050 * @throws IllegalArgumentException if the endpoint indices are out of order
1051 * {@code (fromIndex > toIndex)}
1052 */
1053 public synchronized List<E> subList(int fromIndex, int toIndex) {
1054 return Collections.synchronizedList(super.subList(fromIndex, toIndex),
1055 this);
1056 }
1057
1058 /**
1059 * Removes from this list all of the elements whose index is between
1060 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
1061 * Shifts any succeeding elements to the left (reduces their index).
1062 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
1063 * (If {@code toIndex==fromIndex}, this operation has no effect.)
1064 */
1065 protected synchronized void removeRange(int fromIndex, int toIndex) {
1066 int numMoved = elementCount - toIndex;
1067 System.arraycopy(elementData, toIndex, elementData, fromIndex,
1068 numMoved);
1069
1070 // Let gc do its work
1071 modCount++;
1072 int newElementCount = elementCount - (toIndex-fromIndex);
1073 while (elementCount != newElementCount)
1074 elementData[--elementCount] = null;
1075 }
1076
1077 /**
1078 * Save the state of the {@code Vector} instance to a stream (that
1079 * is, serialize it).
1080 * This method performs synchronization to ensure the consistency
1081 * of the serialized data.
1082 */
1083 private void writeObject(java.io.ObjectOutputStream s)
1084 throws java.io.IOException {
1085 final java.io.ObjectOutputStream.PutField fields = s.putFields();
1086 final Object[] data;
1087 synchronized (this) {
1088 fields.put("capacityIncrement", capacityIncrement);
1089 fields.put("elementCount", elementCount);
1090 data = elementData.clone();
1091 }
1092 fields.put("elementData", data);
1093 s.writeFields();
1094 }
1095
1096 /**
1097 * Returns a list iterator over the elements in this list (in proper
1098 * sequence), starting at the specified position in the list.
1099 * The specified index indicates the first element that would be
1100 * returned by an initial call to {@link ListIterator#next next}.
1101 * An initial call to {@link ListIterator#previous previous} would
1102 * return the element with the specified index minus one.
1103 *
1104 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1105 *
1106 * @throws IndexOutOfBoundsException {@inheritDoc}
1107 */
1108 public synchronized ListIterator<E> listIterator(int index) {
1109 if (index < 0 || index > elementCount)
1110 throw new IndexOutOfBoundsException("Index: "+index);
1111 return new ListItr(index);
1112 }
1113
1114 /**
1115 * Returns a list iterator over the elements in this list (in proper
1116 * sequence).
1117 *
1118 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1119 *
1120 * @see #listIterator(int)
1121 */
1122 public synchronized ListIterator<E> listIterator() {
1123 return new ListItr(0);
1124 }
1125
1126 /**
1127 * Returns an iterator over the elements in this list in proper sequence.
1128 *
1129 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1130 *
1131 * @return an iterator over the elements in this list in proper sequence
1132 */
1133 public synchronized Iterator<E> iterator() {
1134 return new Itr();
1135 }
1136
1137 /**
1138 * An optimized version of AbstractList.Itr
1139 */
1140 private class Itr implements Iterator<E> {
1141 int cursor; // index of next element to return
1142 int lastRet = -1; // index of last element returned; -1 if no such
1143 int expectedModCount = modCount;
1144
1145 public boolean hasNext() {
1146 // Racy but within spec, since modifications are checked
1147 // within or after synchronization in next/previous
1148 return cursor != elementCount;
1149 }
1150
1151 public E next() {
1152 synchronized (Vector.this) {
1153 checkForComodification();
1154 int i = cursor;
1155 if (i >= elementCount)
1156 throw new NoSuchElementException();
1157 cursor = i + 1;
1158 return elementData(lastRet = i);
1159 }
1160 }
1161
1162 public void remove() {
1163 if (lastRet == -1)
1164 throw new IllegalStateException();
1165 synchronized (Vector.this) {
1166 checkForComodification();
1167 Vector.this.remove(lastRet);
1168 expectedModCount = modCount;
1169 }
1170 cursor = lastRet;
1171 lastRet = -1;
1172 }
1173
1174 @Override
1175 public void forEachRemaining(Consumer<? super E> action) {
1176 Objects.requireNonNull(action);
1177 synchronized (Vector.this) {
1178 final int size = elementCount;
1179 int i = cursor;
1180 if (i >= size) {
1181 return;
1182 }
1183 @SuppressWarnings("unchecked")
1184 final E[] elementData = (E[]) Vector.this.elementData;
1185 if (i >= elementData.length) {
1186 throw new ConcurrentModificationException();
1187 }
1188 while (i != size && modCount == expectedModCount) {
1189 action.accept(elementData[i++]);
1190 }
1191 // update once at end of iteration to reduce heap write traffic
1192 cursor = i;
1193 lastRet = i - 1;
1194 checkForComodification();
1195 }
1196 }
1197
1198 final void checkForComodification() {
1199 if (modCount != expectedModCount)
1200 throw new ConcurrentModificationException();
1201 }
1202 }
1203
1204 /**
1205 * An optimized version of AbstractList.ListItr
1206 */
1207 final class ListItr extends Itr implements ListIterator<E> {
1208 ListItr(int index) {
1209 super();
1210 cursor = index;
1211 }
1212
1213 public boolean hasPrevious() {
1214 return cursor != 0;
1215 }
1216
1217 public int nextIndex() {
1218 return cursor;
1219 }
1220
1221 public int previousIndex() {
1222 return cursor - 1;
1223 }
1224
1225 public E previous() {
1226 synchronized (Vector.this) {
1227 checkForComodification();
1228 int i = cursor - 1;
1229 if (i < 0)
1230 throw new NoSuchElementException();
1231 cursor = i;
1232 return elementData(lastRet = i);
1233 }
1234 }
1235
1236 public void set(E e) {
1237 if (lastRet == -1)
1238 throw new IllegalStateException();
1239 synchronized (Vector.this) {
1240 checkForComodification();
1241 Vector.this.set(lastRet, e);
1242 }
1243 }
1244
1245 public void add(E e) {
1246 int i = cursor;
1247 synchronized (Vector.this) {
1248 checkForComodification();
1249 Vector.this.add(i, e);
1250 expectedModCount = modCount;
1251 }
1252 cursor = i + 1;
1253 lastRet = -1;
1254 }
1255 }
1256
1257 @Override
1258 public synchronized void forEach(Consumer<? super E> action) {
1259 Objects.requireNonNull(action);
1260 final int expectedModCount = modCount;
1261 @SuppressWarnings("unchecked")
1262 final E[] elementData = (E[]) this.elementData;
1263 final int elementCount = this.elementCount;
1264 for (int i=0; modCount == expectedModCount && i < elementCount; i++) {
1265 action.accept(elementData[i]);
1266 }
1267 if (modCount != expectedModCount) {
1268 throw new ConcurrentModificationException();
1269 }
1270 }
1271
1272 @Override
1273 @SuppressWarnings("unchecked")
1274 public synchronized boolean removeIf(Predicate<? super E> filter) {
1275 Objects.requireNonNull(filter);
1276 // figure out which elements are to be removed
1277 // any exception thrown from the filter predicate at this stage
1278 // will leave the collection unmodified
1279 int removeCount = 0;
1280 final int size = elementCount;
1281 final BitSet removeSet = new BitSet(size);
1282 final int expectedModCount = modCount;
1283 for (int i=0; modCount == expectedModCount && i < size; i++) {
1284 @SuppressWarnings("unchecked")
1285 final E element = (E) elementData[i];
1286 if (filter.test(element)) {
1287 removeSet.set(i);
1288 removeCount++;
1289 }
1290 }
1291 if (modCount != expectedModCount) {
1292 throw new ConcurrentModificationException();
1293 }
1294
1295 // shift surviving elements left over the spaces left by removed elements
1296 final boolean anyToRemove = removeCount > 0;
1297 if (anyToRemove) {
1298 final int newSize = size - removeCount;
1299 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
1300 i = removeSet.nextClearBit(i);
1301 elementData[j] = elementData[i];
1302 }
1303 for (int k=newSize; k < size; k++) {
1304 elementData[k] = null; // Let gc do its work
1305 }
1306 elementCount = newSize;
1307 if (modCount != expectedModCount) {
1308 throw new ConcurrentModificationException();
1309 }
1310 modCount++;
1311 }
1312
1313 return anyToRemove;
1314 }
1315
1316 @Override
1317 @SuppressWarnings("unchecked")
1318 public synchronized void replaceAll(UnaryOperator<E> operator) {
1319 Objects.requireNonNull(operator);
1320 final int expectedModCount = modCount;
1321 final int size = elementCount;
1322 for (int i=0; modCount == expectedModCount && i < size; i++) {
1323 elementData[i] = operator.apply((E) elementData[i]);
1324 }
1325 if (modCount != expectedModCount) {
1326 throw new ConcurrentModificationException();
1327 }
1328 modCount++;
1329 }
1330
1331 @SuppressWarnings("unchecked")
1332 @Override
1333 public synchronized void sort(Comparator<? super E> c) {
1334 final int expectedModCount = modCount;
1335 Arrays.sort((E[]) elementData, 0, elementCount, c);
1336 if (modCount != expectedModCount) {
1337 throw new ConcurrentModificationException();
1338 }
1339 modCount++;
1340 }
1341
1342 /**
1343 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1344 * and <em>fail-fast</em> {@link Spliterator} over the elements in this
1345 * list.
1346 *
1347 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1348 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
1349 * Overriding implementations should document the reporting of additional
1350 * characteristic values.
1351 *
1352 * @return a {@code Spliterator} over the elements in this list
1353 * @since 1.8
1354 */
1355 @Override
1356 public Spliterator<E> spliterator() {
1357 return new VectorSpliterator<>(this, null, 0, -1, 0);
1358 }
1359
1360 /** Similar to ArrayList Spliterator */
1361 static final class VectorSpliterator<E> implements Spliterator<E> {
1362 private final Vector<E> list;
1363 private Object[] array;
1364 private int index; // current index, modified on advance/split
1365 private int fence; // -1 until used; then one past last index
1366 private int expectedModCount; // initialized when fence set
1367
1368 /** Create new spliterator covering the given range */
1369 VectorSpliterator(Vector<E> list, Object[] array, int origin, int fence,
1370 int expectedModCount) {
1371 this.list = list;
1372 this.array = array;
1373 this.index = origin;
1374 this.fence = fence;
1375 this.expectedModCount = expectedModCount;
1376 }
1377
1378 private int getFence() { // initialize on first use
1379 int hi;
1380 if ((hi = fence) < 0) {
1381 synchronized(list) {
1382 array = list.elementData;
1383 expectedModCount = list.modCount;
1384 hi = fence = list.elementCount;
1385 }
1386 }
1387 return hi;
1388 }
1389
1390 public Spliterator<E> trySplit() {
1391 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1392 return (lo >= mid) ? null :
1393 new VectorSpliterator<>(list, array, lo, index = mid,
1394 expectedModCount);
1395 }
1396
1397 @SuppressWarnings("unchecked")
1398 public boolean tryAdvance(Consumer<? super E> action) {
1399 int i;
1400 if (action == null)
1401 throw new NullPointerException();
1402 if (getFence() > (i = index)) {
1403 index = i + 1;
1404 action.accept((E)array[i]);
1405 if (list.modCount != expectedModCount)
1406 throw new ConcurrentModificationException();
1407 return true;
1408 }
1409 return false;
1410 }
1411
1412 @SuppressWarnings("unchecked")
1413 public void forEachRemaining(Consumer<? super E> action) {
1414 int i, hi; // hoist accesses and checks from loop
1415 Vector<E> lst; Object[] a;
1416 if (action == null)
1417 throw new NullPointerException();
1418 if ((lst = list) != null) {
1419 if ((hi = fence) < 0) {
1420 synchronized(lst) {
1421 expectedModCount = lst.modCount;
1422 a = array = lst.elementData;
1423 hi = fence = lst.elementCount;
1424 }
1425 }
1426 else
1427 a = array;
1428 if (a != null && (i = index) >= 0 && (index = hi) <= a.length) {
1429 while (i < hi)
1430 action.accept((E) a[i++]);
1431 if (lst.modCount == expectedModCount)
1432 return;
1433 }
1434 }
1435 throw new ConcurrentModificationException();
1436 }
1437
1438 public long estimateSize() {
1439 return getFence() - index;
1440 }
1441
1442 public int characteristics() {
1443 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1444 }
1445 }
1446 }