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 *
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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 // defend against c.toArray (incorrectly) not returning Object[]
178 // (see e.g. https://bugs.openjdk.java.net/browse/JDK-6260652)
179 if (elementData.getClass() != Object[].class)
180 elementData = Arrays.copyOf(elementData, elementCount, Object[].class);
181 }
182
183 /**
184 * Copies the components of this vector into the specified array.
185 * The item at index {@code k} in this vector is copied into
186 * component {@code k} of {@code anArray}.
187 *
188 * @param anArray the array into which the components get copied
189 * @throws NullPointerException if the given array is null
190 * @throws IndexOutOfBoundsException if the specified array is not
191 * large enough to hold all the components of this vector
192 * @throws ArrayStoreException if a component of this vector is not of
193 * a runtime type that can be stored in the specified array
194 * @see #toArray(Object[])
195 */
196 public synchronized void copyInto(Object[] anArray) {
197 System.arraycopy(elementData, 0, anArray, 0, elementCount);
198 }
199
200 /**
201 * Trims the capacity of this vector to be the vector's current
202 * size. If the capacity of this vector is larger than its current
203 * size, then the capacity is changed to equal the size by replacing
204 * its internal data array, kept in the field {@code elementData},
205 * with a smaller one. An application can use this operation to
206 * minimize the storage of a vector.
207 */
208 public synchronized void trimToSize() {
209 modCount++;
210 int oldCapacity = elementData.length;
211 if (elementCount < oldCapacity) {
212 elementData = Arrays.copyOf(elementData, elementCount);
213 }
214 }
215
216 /**
217 * Increases the capacity of this vector, if necessary, to ensure
218 * that it can hold at least the number of components specified by
219 * the minimum capacity argument.
220 *
221 * <p>If the current capacity of this vector is less than
222 * {@code minCapacity}, then its capacity is increased by replacing its
223 * internal data array, kept in the field {@code elementData}, with a
224 * larger one. The size of the new data array will be the old size plus
225 * {@code capacityIncrement}, unless the value of
226 * {@code capacityIncrement} is less than or equal to zero, in which case
227 * the new capacity will be twice the old capacity; but if this new size
228 * is still smaller than {@code minCapacity}, then the new capacity will
229 * be {@code minCapacity}.
230 *
231 * @param minCapacity the desired minimum capacity
232 */
233 public synchronized void ensureCapacity(int minCapacity) {
234 if (minCapacity > 0) {
235 modCount++;
236 ensureCapacityHelper(minCapacity);
237 }
238 }
239
240 /**
241 * This implements the unsynchronized semantics of ensureCapacity.
242 * Synchronized methods in this class can internally call this
243 * method for ensuring capacity without incurring the cost of an
244 * extra synchronization.
245 *
246 * @see #ensureCapacity(int)
247 */
248 private void ensureCapacityHelper(int minCapacity) {
249 // overflow-conscious code
250 if (minCapacity - elementData.length > 0)
251 grow(minCapacity);
252 }
253
254 /**
255 * The maximum size of array to allocate.
256 * Some VMs reserve some header words in an array.
257 * Attempts to allocate larger arrays may result in
258 * OutOfMemoryError: Requested array size exceeds VM limit
259 */
260 private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;
261
262 private void grow(int minCapacity) {
263 // overflow-conscious code
264 int oldCapacity = elementData.length;
265 int newCapacity = oldCapacity + ((capacityIncrement > 0) ?
266 capacityIncrement : oldCapacity);
267 if (newCapacity - minCapacity < 0)
268 newCapacity = minCapacity;
269 if (newCapacity - MAX_ARRAY_SIZE > 0)
270 newCapacity = hugeCapacity(minCapacity);
271 elementData = Arrays.copyOf(elementData, newCapacity);
272 }
273
274 private static int hugeCapacity(int minCapacity) {
275 if (minCapacity < 0) // overflow
276 throw new OutOfMemoryError();
277 return (minCapacity > MAX_ARRAY_SIZE) ?
278 Integer.MAX_VALUE :
279 MAX_ARRAY_SIZE;
280 }
281
282 /**
283 * Sets the size of this vector. If the new size is greater than the
284 * current size, new {@code null} items are added to the end of
285 * the vector. If the new size is less than the current size, all
286 * components at index {@code newSize} and greater are discarded.
287 *
288 * @param newSize the new size of this vector
289 * @throws ArrayIndexOutOfBoundsException if the new size is negative
290 */
291 public synchronized void setSize(int newSize) {
292 modCount++;
293 if (newSize > elementCount) {
294 ensureCapacityHelper(newSize);
295 } else {
296 for (int i = newSize ; i < elementCount ; i++) {
297 elementData[i] = null;
298 }
299 }
300 elementCount = newSize;
301 }
302
303 /**
304 * Returns the current capacity of this vector.
305 *
306 * @return the current capacity (the length of its internal
307 * data array, kept in the field {@code elementData}
308 * of this vector)
309 */
310 public synchronized int capacity() {
311 return elementData.length;
312 }
313
314 /**
315 * Returns the number of components in this vector.
316 *
317 * @return the number of components in this vector
318 */
319 public synchronized int size() {
320 return elementCount;
321 }
322
323 /**
324 * Tests if this vector has no components.
325 *
326 * @return {@code true} if and only if this vector has
327 * no components, that is, its size is zero;
328 * {@code false} otherwise.
329 */
330 public synchronized boolean isEmpty() {
331 return elementCount == 0;
332 }
333
334 /**
335 * Returns an enumeration of the components of this vector. The
336 * returned {@code Enumeration} object will generate all items in
337 * this vector. The first item generated is the item at index {@code 0},
338 * then the item at index {@code 1}, and so on. If the vector is
339 * structurally modified while enumerating over the elements then the
340 * results of enumerating are undefined.
341 *
342 * @return an enumeration of the components of this vector
343 * @see Iterator
344 */
345 public Enumeration<E> elements() {
346 return new Enumeration<E>() {
347 int count = 0;
348
349 public boolean hasMoreElements() {
350 return count < elementCount;
351 }
352
353 public E nextElement() {
354 synchronized (Vector.this) {
355 if (count < elementCount) {
356 return elementData(count++);
357 }
358 }
359 throw new NoSuchElementException("Vector Enumeration");
360 }
361 };
362 }
363
364 /**
365 * Returns {@code true} if this vector contains the specified element.
366 * More formally, returns {@code true} if and only if this vector
367 * contains at least one element {@code e} such that
368 * <code>(o==null ? e==null : o.equals(e))</code>.
369 *
370 * @param o element whose presence in this vector is to be tested
371 * @return {@code true} if this vector contains the specified element
372 */
373 public boolean contains(Object o) {
374 return indexOf(o, 0) >= 0;
375 }
376
377 /**
378 * Returns the index of the first occurrence of the specified element
379 * in this vector, or -1 if this vector does not contain the element.
380 * More formally, returns the lowest index {@code i} such that
381 * <code>(o==null ? get(i)==null : o.equals(get(i)))</code>,
382 * or -1 if there is no such index.
383 *
384 * @param o element to search for
385 * @return the index of the first occurrence of the specified element in
386 * this vector, or -1 if this vector does not contain the element
387 */
388 public int indexOf(Object o) {
389 return indexOf(o, 0);
390 }
391
392 /**
393 * Returns the index of the first occurrence of the specified element in
394 * this vector, searching forwards from {@code index}, or returns -1 if
395 * the element is not found.
396 * More formally, returns the lowest index {@code i} such that
397 * <code>(i >= index && (o==null ? get(i)==null : o.equals(get(i))))</code>,
398 * or -1 if there is no such index.
399 *
400 * @param o element to search for
401 * @param index index to start searching from
402 * @return the index of the first occurrence of the element in
403 * this vector at position {@code index} or later in the vector;
404 * {@code -1} if the element is not found.
405 * @throws IndexOutOfBoundsException if the specified index is negative
406 * @see Object#equals(Object)
407 */
408 public synchronized int indexOf(Object o, int index) {
409 if (o == null) {
410 for (int i = index ; i < elementCount ; i++)
411 if (elementData[i]==null)
412 return i;
413 } else {
414 for (int i = index ; i < elementCount ; i++)
415 if (o.equals(elementData[i]))
416 return i;
417 }
418 return -1;
419 }
420
421 /**
422 * Returns the index of the last occurrence of the specified element
423 * in this vector, or -1 if this vector does not contain the element.
424 * More formally, returns the highest index {@code i} such that
425 * <code>(o==null ? get(i)==null : o.equals(get(i)))</code>,
426 * or -1 if there is no such index.
427 *
428 * @param o element to search for
429 * @return the index of the last occurrence of the specified element in
430 * this vector, or -1 if this vector does not contain the element
431 */
432 public synchronized int lastIndexOf(Object o) {
433 return lastIndexOf(o, elementCount-1);
434 }
435
436 /**
437 * Returns the index of the last occurrence of the specified element in
438 * this vector, searching backwards from {@code index}, or returns -1 if
439 * the element is not found.
440 * More formally, returns the highest index {@code i} such that
441 * <code>(i <= index && (o==null ? get(i)==null : o.equals(get(i))))</code>,
442 * or -1 if there is no such index.
443 *
444 * @param o element to search for
445 * @param index index to start searching backwards from
446 * @return the index of the last occurrence of the element at position
447 * less than or equal to {@code index} in this vector;
448 * -1 if the element is not found.
449 * @throws IndexOutOfBoundsException if the specified index is greater
450 * than or equal to the current size of this vector
451 */
452 public synchronized int lastIndexOf(Object o, int index) {
453 if (index >= elementCount)
454 throw new IndexOutOfBoundsException(index + " >= "+ elementCount);
455
456 if (o == null) {
457 for (int i = index; i >= 0; i--)
458 if (elementData[i]==null)
459 return i;
460 } else {
461 for (int i = index; i >= 0; i--)
462 if (o.equals(elementData[i]))
463 return i;
464 }
465 return -1;
466 }
467
468 /**
469 * Returns the component at the specified index.
470 *
471 * <p>This method is identical in functionality to the {@link #get(int)}
472 * method (which is part of the {@link List} interface).
473 *
474 * @param index an index into this vector
475 * @return the component at the specified index
476 * @throws ArrayIndexOutOfBoundsException if the index is out of range
477 * ({@code index < 0 || index >= size()})
478 */
479 public synchronized E elementAt(int index) {
480 if (index >= elementCount) {
481 throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);
482 }
483
484 return elementData(index);
485 }
486
487 /**
488 * Returns the first component (the item at index {@code 0}) of
489 * this vector.
490 *
491 * @return the first component of this vector
492 * @throws NoSuchElementException if this vector has no components
493 */
494 public synchronized E firstElement() {
495 if (elementCount == 0) {
496 throw new NoSuchElementException();
497 }
498 return elementData(0);
499 }
500
501 /**
502 * Returns the last component of the vector.
503 *
504 * @return the last component of the vector, i.e., the component at index
505 * <code>size() - 1</code>.
506 * @throws NoSuchElementException if this vector is empty
507 */
508 public synchronized E lastElement() {
509 if (elementCount == 0) {
510 throw new NoSuchElementException();
511 }
512 return elementData(elementCount - 1);
513 }
514
515 /**
516 * Sets the component at the specified {@code index} of this
517 * vector to be the specified object. The previous component at that
518 * position is discarded.
519 *
520 * <p>The index must be a value greater than or equal to {@code 0}
521 * and less than the current size of the vector.
522 *
523 * <p>This method is identical in functionality to the
524 * {@link #set(int, Object) set(int, E)}
525 * method (which is part of the {@link List} interface). Note that the
526 * {@code set} method reverses the order of the parameters, to more closely
527 * match array usage. Note also that the {@code set} method returns the
528 * old value that was stored at the specified position.
529 *
530 * @param obj what the component is to be set to
531 * @param index the specified index
532 * @throws ArrayIndexOutOfBoundsException if the index is out of range
533 * ({@code index < 0 || index >= size()})
534 */
535 public synchronized void setElementAt(E obj, int index) {
536 if (index >= elementCount) {
537 throw new ArrayIndexOutOfBoundsException(index + " >= " +
538 elementCount);
539 }
540 elementData[index] = obj;
541 }
542
543 /**
544 * Deletes the component at the specified index. Each component in
545 * this vector with an index greater or equal to the specified
546 * {@code index} is shifted downward to have an index one
547 * smaller than the value it had previously. The size of this vector
548 * is decreased by {@code 1}.
549 *
550 * <p>The index must be a value greater than or equal to {@code 0}
551 * and less than the current size of the vector.
552 *
553 * <p>This method is identical in functionality to the {@link #remove(int)}
554 * method (which is part of the {@link List} interface). Note that the
555 * {@code remove} method returns the old value that was stored at the
556 * specified position.
557 *
558 * @param index the index of the object to remove
559 * @throws ArrayIndexOutOfBoundsException if the index is out of range
560 * ({@code index < 0 || index >= size()})
561 */
562 public synchronized void removeElementAt(int index) {
563 if (index >= elementCount) {
564 throw new ArrayIndexOutOfBoundsException(index + " >= " +
565 elementCount);
566 }
567 else if (index < 0) {
568 throw new ArrayIndexOutOfBoundsException(index);
569 }
570 int j = elementCount - index - 1;
571 if (j > 0) {
572 System.arraycopy(elementData, index + 1, elementData, index, j);
573 }
574 modCount++;
575 elementCount--;
576 elementData[elementCount] = null; /* to let gc do its work */
577 }
578
579 /**
580 * Inserts the specified object as a component in this vector at the
581 * specified {@code index}. Each component in this vector with
582 * an index greater or equal to the specified {@code index} is
583 * shifted upward to have an index one greater than the value it had
584 * previously.
585 *
586 * <p>The index must be a value greater than or equal to {@code 0}
587 * and less than or equal to the current size of the vector. (If the
588 * index is equal to the current size of the vector, the new element
589 * is appended to the Vector.)
590 *
591 * <p>This method is identical in functionality to the
592 * {@link #add(int, Object) add(int, E)}
593 * method (which is part of the {@link List} interface). Note that the
594 * {@code add} method reverses the order of the parameters, to more closely
595 * match array usage.
596 *
597 * @param obj the component to insert
598 * @param index where to insert the new component
599 * @throws ArrayIndexOutOfBoundsException if the index is out of range
600 * ({@code index < 0 || index > size()})
601 */
602 public synchronized void insertElementAt(E obj, int index) {
603 if (index > elementCount) {
604 throw new ArrayIndexOutOfBoundsException(index
605 + " > " + elementCount);
606 }
607 ensureCapacityHelper(elementCount + 1);
608 System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);
609 elementData[index] = obj;
610 modCount++;
611 elementCount++;
612 }
613
614 /**
615 * Adds the specified component to the end of this vector,
616 * increasing its size by one. The capacity of this vector is
617 * increased if its size becomes greater than its capacity.
618 *
619 * <p>This method is identical in functionality to the
620 * {@link #add(Object) add(E)}
621 * method (which is part of the {@link List} interface).
622 *
623 * @param obj the component to be added
624 */
625 public synchronized void addElement(E obj) {
626 ensureCapacityHelper(elementCount + 1);
627 modCount++;
628 elementData[elementCount++] = obj;
629 }
630
631 /**
632 * Removes the first (lowest-indexed) occurrence of the argument
633 * from this vector. If the object is found in this vector, each
634 * component in the vector with an index greater or equal to the
635 * object's index is shifted downward to have an index one smaller
636 * than the value it had previously.
637 *
638 * <p>This method is identical in functionality to the
639 * {@link #remove(Object)} method (which is part of the
640 * {@link List} interface).
641 *
642 * @param obj the component to be removed
643 * @return {@code true} if the argument was a component of this
644 * vector; {@code false} otherwise.
645 */
646 public synchronized boolean removeElement(Object obj) {
647 modCount++;
648 int i = indexOf(obj);
649 if (i >= 0) {
650 removeElementAt(i);
651 return true;
652 }
653 return false;
654 }
655
656 /**
657 * Removes all components from this vector and sets its size to zero.
658 *
659 * <p>This method is identical in functionality to the {@link #clear}
660 * method (which is part of the {@link List} interface).
661 */
662 public synchronized void removeAllElements() {
663 // Let gc do its work
664 for (int i = 0; i < elementCount; i++)
665 elementData[i] = null;
666
667 modCount++;
668 elementCount = 0;
669 }
670
671 /**
672 * Returns a clone of this vector. The copy will contain a
673 * reference to a clone of the internal data array, not a reference
674 * to the original internal data array of this {@code Vector} object.
675 *
676 * @return a clone of this vector
677 */
678 public synchronized Object clone() {
679 try {
680 @SuppressWarnings("unchecked")
681 Vector<E> v = (Vector<E>) super.clone();
682 v.elementData = Arrays.copyOf(elementData, elementCount);
683 v.modCount = 0;
684 return v;
685 } catch (CloneNotSupportedException e) {
686 // this shouldn't happen, since we are Cloneable
687 throw new InternalError(e);
688 }
689 }
690
691 /**
692 * Returns an array containing all of the elements in this Vector
693 * in the correct order.
694 *
695 * @since 1.2
696 */
697 public synchronized Object[] toArray() {
698 return Arrays.copyOf(elementData, elementCount);
699 }
700
701 /**
702 * Returns an array containing all of the elements in this Vector in the
703 * correct order; the runtime type of the returned array is that of the
704 * specified array. If the Vector fits in the specified array, it is
705 * returned therein. Otherwise, a new array is allocated with the runtime
706 * type of the specified array and the size of this Vector.
707 *
708 * <p>If the Vector fits in the specified array with room to spare
709 * (i.e., the array has more elements than the Vector),
710 * the element in the array immediately following the end of the
711 * Vector is set to null. (This is useful in determining the length
712 * of the Vector <em>only</em> if the caller knows that the Vector
713 * does not contain any null elements.)
714 *
715 * @param <T> type of array elements. The same type as {@code <E>} or a
716 * supertype of {@code <E>}.
717 * @param a the array into which the elements of the Vector are to
718 * be stored, if it is big enough; otherwise, a new array of the
719 * same runtime type is allocated for this purpose.
720 * @return an array containing the elements of the Vector
721 * @throws ArrayStoreException if the runtime type of a, {@code <T>}, is not
722 * a supertype of the runtime type, {@code <E>}, of every element in this
723 * Vector
724 * @throws NullPointerException if the given array is null
725 * @since 1.2
726 */
727 @SuppressWarnings("unchecked")
728 public synchronized <T> T[] toArray(T[] a) {
729 if (a.length < elementCount)
730 return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());
731
732 System.arraycopy(elementData, 0, a, 0, elementCount);
733
734 if (a.length > elementCount)
735 a[elementCount] = null;
736
737 return a;
738 }
739
740 // Positional Access Operations
741
742 @SuppressWarnings("unchecked")
743 E elementData(int index) {
744 return (E) elementData[index];
745 }
746
747 /**
748 * Returns the element at the specified position in this Vector.
749 *
750 * @param index index of the element to return
751 * @return object at the specified index
752 * @throws ArrayIndexOutOfBoundsException if the index is out of range
753 * ({@code index < 0 || index >= size()})
754 * @since 1.2
755 */
756 public synchronized E get(int index) {
757 if (index >= elementCount)
758 throw new ArrayIndexOutOfBoundsException(index);
759
760 return elementData(index);
761 }
762
763 /**
764 * Replaces the element at the specified position in this Vector with the
765 * specified element.
766 *
767 * @param index index of the element to replace
768 * @param element element to be stored at the specified position
769 * @return the element previously at the specified position
770 * @throws ArrayIndexOutOfBoundsException if the index is out of range
771 * ({@code index < 0 || index >= size()})
772 * @since 1.2
773 */
774 public synchronized E set(int index, E element) {
775 if (index >= elementCount)
776 throw new ArrayIndexOutOfBoundsException(index);
777
778 E oldValue = elementData(index);
779 elementData[index] = element;
780 return oldValue;
781 }
782
783 /**
784 * Appends the specified element to the end of this Vector.
785 *
786 * @param e element to be appended to this Vector
787 * @return {@code true} (as specified by {@link Collection#add})
788 * @since 1.2
789 */
790 public synchronized boolean add(E e) {
791 ensureCapacityHelper(elementCount + 1);
792 modCount++;
793 elementData[elementCount++] = e;
794 return true;
795 }
796
797 /**
798 * Removes the first occurrence of the specified element in this Vector
799 * If the Vector does not contain the element, it is unchanged. More
800 * formally, removes the element with the lowest index i such that
801 * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such
802 * an element exists).
803 *
804 * @param o element to be removed from this Vector, if present
805 * @return true if the Vector contained the specified element
806 * @since 1.2
807 */
808 public boolean remove(Object o) {
809 return removeElement(o);
810 }
811
812 /**
813 * Inserts the specified element at the specified position in this Vector.
814 * Shifts the element currently at that position (if any) and any
815 * subsequent elements to the right (adds one to their indices).
816 *
817 * @param index index at which the specified element is to be inserted
818 * @param element element to be inserted
819 * @throws ArrayIndexOutOfBoundsException if the index is out of range
820 * ({@code index < 0 || index > size()})
821 * @since 1.2
822 */
823 public void add(int index, E element) {
824 insertElementAt(element, index);
825 }
826
827 /**
828 * Removes the element at the specified position in this Vector.
829 * Shifts any subsequent elements to the left (subtracts one from their
830 * indices). Returns the element that was removed from the Vector.
831 *
832 * @throws ArrayIndexOutOfBoundsException if the index is out of range
833 * ({@code index < 0 || index >= size()})
834 * @param index the index of the element to be removed
835 * @return element that was removed
836 * @since 1.2
837 */
838 public synchronized E remove(int index) {
839 modCount++;
840 if (index >= elementCount)
841 throw new ArrayIndexOutOfBoundsException(index);
842 E oldValue = elementData(index);
843
844 int numMoved = elementCount - index - 1;
845 if (numMoved > 0)
846 System.arraycopy(elementData, index+1, elementData, index,
847 numMoved);
848 elementData[--elementCount] = null; // Let gc do its work
849
850 return oldValue;
851 }
852
853 /**
854 * Removes all of the elements from this Vector. The Vector will
855 * be empty after this call returns (unless it throws an exception).
856 *
857 * @since 1.2
858 */
859 public void clear() {
860 removeAllElements();
861 }
862
863 // Bulk Operations
864
865 /**
866 * Returns true if this Vector contains all of the elements in the
867 * specified Collection.
868 *
869 * @param c a collection whose elements will be tested for containment
870 * in this Vector
871 * @return true if this Vector contains all of the elements in the
872 * specified collection
873 * @throws NullPointerException if the specified collection is null
874 */
875 public synchronized boolean containsAll(Collection<?> c) {
876 return super.containsAll(c);
877 }
878
879 /**
880 * Appends all of the elements in the specified Collection to the end of
881 * this Vector, in the order that they are returned by the specified
882 * Collection's Iterator. The behavior of this operation is undefined if
883 * the specified Collection is modified while the operation is in progress.
884 * (This implies that the behavior of this call is undefined if the
885 * specified Collection is this Vector, and this Vector is nonempty.)
886 *
887 * @param c elements to be inserted into this Vector
888 * @return {@code true} if this Vector changed as a result of the call
889 * @throws NullPointerException if the specified collection is null
890 * @since 1.2
891 */
892 public boolean addAll(Collection<? extends E> c) {
893 Object[] a = c.toArray();
894 int numNew = a.length;
895 if (numNew > 0) {
896 synchronized (this) {
897 ensureCapacityHelper(elementCount + numNew);
898 System.arraycopy(a, 0, elementData, elementCount, numNew);
899 modCount++;
900 elementCount += numNew;
901 }
902 }
903 return numNew > 0;
904 }
905
906 /**
907 * Removes from this Vector all of its elements that are contained in the
908 * specified Collection.
909 *
910 * @param c a collection of elements to be removed from the Vector
911 * @return true if this Vector changed as a result of the call
912 * @throws ClassCastException if the types of one or more elements
913 * in this vector are incompatible with the specified
914 * collection
915 * (<a href="Collection.html#optional-restrictions">optional</a>)
916 * @throws NullPointerException if this vector contains one or more null
917 * elements and the specified collection does not support null
918 * elements
919 * (<a href="Collection.html#optional-restrictions">optional</a>),
920 * or if the specified collection is null
921 * @since 1.2
922 */
923 public synchronized boolean removeAll(Collection<?> c) {
924 return super.removeAll(c);
925 }
926
927 /**
928 * Retains only the elements in this Vector that are contained in the
929 * specified Collection. In other words, removes from this Vector all
930 * of its elements that are not contained in the specified Collection.
931 *
932 * @param c a collection of elements to be retained in this Vector
933 * (all other elements are removed)
934 * @return true if this Vector changed as a result of the call
935 * @throws ClassCastException if the types of one or more elements
936 * in this vector are incompatible with the specified
937 * collection
938 * (<a href="Collection.html#optional-restrictions">optional</a>)
939 * @throws NullPointerException if this vector contains one or more null
940 * elements and the specified collection does not support null
941 * elements
942 * (<a href="Collection.html#optional-restrictions">optional</a>),
943 * or if the specified collection is null
944 * @since 1.2
945 */
946 public synchronized boolean retainAll(Collection<?> c) {
947 return super.retainAll(c);
948 }
949
950 /**
951 * Inserts all of the elements in the specified Collection into this
952 * Vector at the specified position. Shifts the element currently at
953 * that position (if any) and any subsequent elements to the right
954 * (increases their indices). The new elements will appear in the Vector
955 * in the order that they are returned by the specified Collection's
956 * iterator.
957 *
958 * @param index index at which to insert the first element from the
959 * specified collection
960 * @param c elements to be inserted into this Vector
961 * @return {@code true} if this Vector changed as a result of the call
962 * @throws ArrayIndexOutOfBoundsException if the index is out of range
963 * ({@code index < 0 || index > size()})
964 * @throws NullPointerException if the specified collection is null
965 * @since 1.2
966 */
967 public synchronized boolean addAll(int index, Collection<? extends E> c) {
968 if (index < 0 || index > elementCount)
969 throw new ArrayIndexOutOfBoundsException(index);
970
971 Object[] a = c.toArray();
972 int numNew = a.length;
973
974 if (numNew > 0) {
975 ensureCapacityHelper(elementCount + numNew);
976
977 int numMoved = elementCount - index;
978 if (numMoved > 0)
979 System.arraycopy(elementData, index, elementData,
980 index + numNew, numMoved);
981
982 System.arraycopy(a, 0, elementData, index, numNew);
983 elementCount += numNew;
984 modCount++;
985 }
986 return numNew > 0;
987 }
988
989 /**
990 * Compares the specified Object with this Vector for equality. Returns
991 * true if and only if the specified Object is also a List, both Lists
992 * have the same size, and all corresponding pairs of elements in the two
993 * Lists are <em>equal</em>. (Two elements {@code e1} and
994 * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null :
995 * e1.equals(e2))}.) In other words, two Lists are defined to be
996 * equal if they contain the same elements in the same order.
997 *
998 * @param o the Object to be compared for equality with this Vector
999 * @return true if the specified Object is equal to this Vector
1000 */
1001 public synchronized boolean equals(Object o) {
1002 return super.equals(o);
1003 }
1004
1005 /**
1006 * Returns the hash code value for this Vector.
1007 */
1008 public synchronized int hashCode() {
1009 return super.hashCode();
1010 }
1011
1012 /**
1013 * Returns a string representation of this Vector, containing
1014 * the String representation of each element.
1015 */
1016 public synchronized String toString() {
1017 return super.toString();
1018 }
1019
1020 /**
1021 * Returns a view of the portion of this List between fromIndex,
1022 * inclusive, and toIndex, exclusive. (If fromIndex and toIndex are
1023 * equal, the returned List is empty.) The returned List is backed by this
1024 * List, so changes in the returned List are reflected in this List, and
1025 * vice-versa. The returned List supports all of the optional List
1026 * operations supported by this List.
1027 *
1028 * <p>This method eliminates the need for explicit range operations (of
1029 * the sort that commonly exist for arrays). Any operation that expects
1030 * a List can be used as a range operation by operating on a subList view
1031 * instead of a whole List. For example, the following idiom
1032 * removes a range of elements from a List:
1033 * <pre>
1034 * list.subList(from, to).clear();
1035 * </pre>
1036 * Similar idioms may be constructed for indexOf and lastIndexOf,
1037 * and all of the algorithms in the Collections class can be applied to
1038 * a subList.
1039 *
1040 * <p>The semantics of the List returned by this method become undefined if
1041 * the backing list (i.e., this List) is <i>structurally modified</i> in
1042 * any way other than via the returned List. (Structural modifications are
1043 * those that change the size of the List, or otherwise perturb it in such
1044 * a fashion that iterations in progress may yield incorrect results.)
1045 *
1046 * @param fromIndex low endpoint (inclusive) of the subList
1047 * @param toIndex high endpoint (exclusive) of the subList
1048 * @return a view of the specified range within this List
1049 * @throws IndexOutOfBoundsException if an endpoint index value is out of range
1050 * {@code (fromIndex < 0 || toIndex > size)}
1051 * @throws IllegalArgumentException if the endpoint indices are out of order
1052 * {@code (fromIndex > toIndex)}
1053 */
1054 public synchronized List<E> subList(int fromIndex, int toIndex) {
1055 return Collections.synchronizedList(super.subList(fromIndex, toIndex),
1056 this);
1057 }
1058
1059 /**
1060 * Removes from this list all of the elements whose index is between
1061 * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
1062 * Shifts any succeeding elements to the left (reduces their index).
1063 * This call shortens the list by {@code (toIndex - fromIndex)} elements.
1064 * (If {@code toIndex==fromIndex}, this operation has no effect.)
1065 */
1066 protected synchronized void removeRange(int fromIndex, int toIndex) {
1067 int numMoved = elementCount - toIndex;
1068 System.arraycopy(elementData, toIndex, elementData, fromIndex,
1069 numMoved);
1070
1071 // Let gc do its work
1072 modCount++;
1073 int newElementCount = elementCount - (toIndex-fromIndex);
1074 while (elementCount != newElementCount)
1075 elementData[--elementCount] = null;
1076 }
1077
1078 /**
1079 * Save the state of the {@code Vector} instance to a stream (that
1080 * is, serialize it).
1081 * This method performs synchronization to ensure the consistency
1082 * of the serialized data.
1083 */
1084 private void writeObject(java.io.ObjectOutputStream s)
1085 throws java.io.IOException {
1086 final java.io.ObjectOutputStream.PutField fields = s.putFields();
1087 final Object[] data;
1088 synchronized (this) {
1089 fields.put("capacityIncrement", capacityIncrement);
1090 fields.put("elementCount", elementCount);
1091 data = elementData.clone();
1092 }
1093 fields.put("elementData", data);
1094 s.writeFields();
1095 }
1096
1097 /**
1098 * Returns a list iterator over the elements in this list (in proper
1099 * sequence), starting at the specified position in the list.
1100 * The specified index indicates the first element that would be
1101 * returned by an initial call to {@link ListIterator#next next}.
1102 * An initial call to {@link ListIterator#previous previous} would
1103 * return the element with the specified index minus one.
1104 *
1105 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1106 *
1107 * @throws IndexOutOfBoundsException {@inheritDoc}
1108 */
1109 public synchronized ListIterator<E> listIterator(int index) {
1110 if (index < 0 || index > elementCount)
1111 throw new IndexOutOfBoundsException("Index: "+index);
1112 return new ListItr(index);
1113 }
1114
1115 /**
1116 * Returns a list iterator over the elements in this list (in proper
1117 * sequence).
1118 *
1119 * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1120 *
1121 * @see #listIterator(int)
1122 */
1123 public synchronized ListIterator<E> listIterator() {
1124 return new ListItr(0);
1125 }
1126
1127 /**
1128 * Returns an iterator over the elements in this list in proper sequence.
1129 *
1130 * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
1131 *
1132 * @return an iterator over the elements in this list in proper sequence
1133 */
1134 public synchronized Iterator<E> iterator() {
1135 return new Itr();
1136 }
1137
1138 /**
1139 * An optimized version of AbstractList.Itr
1140 */
1141 private class Itr implements Iterator<E> {
1142 int cursor; // index of next element to return
1143 int lastRet = -1; // index of last element returned; -1 if no such
1144 int expectedModCount = modCount;
1145
1146 public boolean hasNext() {
1147 // Racy but within spec, since modifications are checked
1148 // within or after synchronization in next/previous
1149 return cursor != elementCount;
1150 }
1151
1152 public E next() {
1153 synchronized (Vector.this) {
1154 checkForComodification();
1155 int i = cursor;
1156 if (i >= elementCount)
1157 throw new NoSuchElementException();
1158 cursor = i + 1;
1159 return elementData(lastRet = i);
1160 }
1161 }
1162
1163 public void remove() {
1164 if (lastRet == -1)
1165 throw new IllegalStateException();
1166 synchronized (Vector.this) {
1167 checkForComodification();
1168 Vector.this.remove(lastRet);
1169 expectedModCount = modCount;
1170 }
1171 cursor = lastRet;
1172 lastRet = -1;
1173 }
1174
1175 @Override
1176 public void forEachRemaining(Consumer<? super E> action) {
1177 Objects.requireNonNull(action);
1178 synchronized (Vector.this) {
1179 final int size = elementCount;
1180 int i = cursor;
1181 if (i >= size) {
1182 return;
1183 }
1184 @SuppressWarnings("unchecked")
1185 final E[] elementData = (E[]) Vector.this.elementData;
1186 if (i >= elementData.length) {
1187 throw new ConcurrentModificationException();
1188 }
1189 while (i != size && modCount == expectedModCount) {
1190 action.accept(elementData[i++]);
1191 }
1192 // update once at end of iteration to reduce heap write traffic
1193 cursor = i;
1194 lastRet = i - 1;
1195 checkForComodification();
1196 }
1197 }
1198
1199 final void checkForComodification() {
1200 if (modCount != expectedModCount)
1201 throw new ConcurrentModificationException();
1202 }
1203 }
1204
1205 /**
1206 * An optimized version of AbstractList.ListItr
1207 */
1208 final class ListItr extends Itr implements ListIterator<E> {
1209 ListItr(int index) {
1210 super();
1211 cursor = index;
1212 }
1213
1214 public boolean hasPrevious() {
1215 return cursor != 0;
1216 }
1217
1218 public int nextIndex() {
1219 return cursor;
1220 }
1221
1222 public int previousIndex() {
1223 return cursor - 1;
1224 }
1225
1226 public E previous() {
1227 synchronized (Vector.this) {
1228 checkForComodification();
1229 int i = cursor - 1;
1230 if (i < 0)
1231 throw new NoSuchElementException();
1232 cursor = i;
1233 return elementData(lastRet = i);
1234 }
1235 }
1236
1237 public void set(E e) {
1238 if (lastRet == -1)
1239 throw new IllegalStateException();
1240 synchronized (Vector.this) {
1241 checkForComodification();
1242 Vector.this.set(lastRet, e);
1243 }
1244 }
1245
1246 public void add(E e) {
1247 int i = cursor;
1248 synchronized (Vector.this) {
1249 checkForComodification();
1250 Vector.this.add(i, e);
1251 expectedModCount = modCount;
1252 }
1253 cursor = i + 1;
1254 lastRet = -1;
1255 }
1256 }
1257
1258 @Override
1259 public synchronized void forEach(Consumer<? super E> action) {
1260 Objects.requireNonNull(action);
1261 final int expectedModCount = modCount;
1262 @SuppressWarnings("unchecked")
1263 final E[] elementData = (E[]) this.elementData;
1264 final int elementCount = this.elementCount;
1265 for (int i=0; modCount == expectedModCount && i < elementCount; i++) {
1266 action.accept(elementData[i]);
1267 }
1268 if (modCount != expectedModCount) {
1269 throw new ConcurrentModificationException();
1270 }
1271 }
1272
1273 @Override
1274 @SuppressWarnings("unchecked")
1275 public synchronized boolean removeIf(Predicate<? super E> filter) {
1276 Objects.requireNonNull(filter);
1277 // figure out which elements are to be removed
1278 // any exception thrown from the filter predicate at this stage
1279 // will leave the collection unmodified
1280 int removeCount = 0;
1281 final int size = elementCount;
1282 final BitSet removeSet = new BitSet(size);
1283 final int expectedModCount = modCount;
1284 for (int i=0; modCount == expectedModCount && i < size; i++) {
1285 @SuppressWarnings("unchecked")
1286 final E element = (E) elementData[i];
1287 if (filter.test(element)) {
1288 removeSet.set(i);
1289 removeCount++;
1290 }
1291 }
1292 if (modCount != expectedModCount) {
1293 throw new ConcurrentModificationException();
1294 }
1295
1296 // shift surviving elements left over the spaces left by removed elements
1297 final boolean anyToRemove = removeCount > 0;
1298 if (anyToRemove) {
1299 final int newSize = size - removeCount;
1300 for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
1301 i = removeSet.nextClearBit(i);
1302 elementData[j] = elementData[i];
1303 }
1304 for (int k=newSize; k < size; k++) {
1305 elementData[k] = null; // Let gc do its work
1306 }
1307 elementCount = newSize;
1308 if (modCount != expectedModCount) {
1309 throw new ConcurrentModificationException();
1310 }
1311 modCount++;
1312 }
1313
1314 return anyToRemove;
1315 }
1316
1317 @Override
1318 @SuppressWarnings("unchecked")
1319 public synchronized void replaceAll(UnaryOperator<E> operator) {
1320 Objects.requireNonNull(operator);
1321 final int expectedModCount = modCount;
1322 final int size = elementCount;
1323 for (int i=0; modCount == expectedModCount && i < size; i++) {
1324 elementData[i] = operator.apply((E) elementData[i]);
1325 }
1326 if (modCount != expectedModCount) {
1327 throw new ConcurrentModificationException();
1328 }
1329 modCount++;
1330 }
1331
1332 @SuppressWarnings("unchecked")
1333 @Override
1334 public synchronized void sort(Comparator<? super E> c) {
1335 final int expectedModCount = modCount;
1336 Arrays.sort((E[]) elementData, 0, elementCount, c);
1337 if (modCount != expectedModCount) {
1338 throw new ConcurrentModificationException();
1339 }
1340 modCount++;
1341 }
1342
1343 /**
1344 * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
1345 * and <em>fail-fast</em> {@link Spliterator} over the elements in this
1346 * list.
1347 *
1348 * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
1349 * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
1350 * Overriding implementations should document the reporting of additional
1351 * characteristic values.
1352 *
1353 * @return a {@code Spliterator} over the elements in this list
1354 * @since 1.8
1355 */
1356 @Override
1357 public Spliterator<E> spliterator() {
1358 return new VectorSpliterator<>(this, null, 0, -1, 0);
1359 }
1360
1361 /** Similar to ArrayList Spliterator */
1362 static final class VectorSpliterator<E> implements Spliterator<E> {
1363 private final Vector<E> list;
1364 private Object[] array;
1365 private int index; // current index, modified on advance/split
1366 private int fence; // -1 until used; then one past last index
1367 private int expectedModCount; // initialized when fence set
1368
1369 /** Create new spliterator covering the given range */
1370 VectorSpliterator(Vector<E> list, Object[] array, int origin, int fence,
1371 int expectedModCount) {
1372 this.list = list;
1373 this.array = array;
1374 this.index = origin;
1375 this.fence = fence;
1376 this.expectedModCount = expectedModCount;
1377 }
1378
1379 private int getFence() { // initialize on first use
1380 int hi;
1381 if ((hi = fence) < 0) {
1382 synchronized(list) {
1383 array = list.elementData;
1384 expectedModCount = list.modCount;
1385 hi = fence = list.elementCount;
1386 }
1387 }
1388 return hi;
1389 }
1390
1391 public Spliterator<E> trySplit() {
1392 int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
1393 return (lo >= mid) ? null :
1394 new VectorSpliterator<>(list, array, lo, index = mid,
1395 expectedModCount);
1396 }
1397
1398 @SuppressWarnings("unchecked")
1399 public boolean tryAdvance(Consumer<? super E> action) {
1400 int i;
1401 if (action == null)
1402 throw new NullPointerException();
1403 if (getFence() > (i = index)) {
1404 index = i + 1;
1405 action.accept((E)array[i]);
1406 if (list.modCount != expectedModCount)
1407 throw new ConcurrentModificationException();
1408 return true;
1409 }
1410 return false;
1411 }
1412
1413 @SuppressWarnings("unchecked")
1414 public void forEachRemaining(Consumer<? super E> action) {
1415 int i, hi; // hoist accesses and checks from loop
1416 Vector<E> lst; Object[] a;
1417 if (action == null)
1418 throw new NullPointerException();
1419 if ((lst = list) != null) {
1420 if ((hi = fence) < 0) {
1421 synchronized(lst) {
1422 expectedModCount = lst.modCount;
1423 a = array = lst.elementData;
1424 hi = fence = lst.elementCount;
1425 }
1426 }
1427 else
1428 a = array;
1429 if (a != null && (i = index) >= 0 && (index = hi) <= a.length) {
1430 while (i < hi)
1431 action.accept((E) a[i++]);
1432 if (lst.modCount == expectedModCount)
1433 return;
1434 }
1435 }
1436 throw new ConcurrentModificationException();
1437 }
1438
1439 public long estimateSize() {
1440 return getFence() - index;
1441 }
1442
1443 public int characteristics() {
1444 return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
1445 }
1446 }
1447 }