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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package java.util;

/**

 * The {@code Vector} class implements a growable array of

 * objects. Like an array, it contains components that can be

 * accessed using an integer index. However, the size of a

 * {@code Vector} can grow or shrink as needed to accommodate

 * adding and removing items after the {@code Vector} has been created.

 *

 * <p>Each vector tries to optimize storage management by maintaining a

 * {@code capacity} and a {@code capacityIncrement}. The

 * {@code capacity} is always at least as large as the vector

 * size; it is usually larger because as components are added to the

 * vector, the vector's storage increases in chunks the size of

 * {@code capacityIncrement}. An application can increase the

 * capacity of a vector before inserting a large number of

 * components; this reduces the amount of incremental reallocation.

 *

 * <p><a name="fail-fast"/>

 * The iterators returned by this class's {@link #iterator() iterator} and

 * {@link #listIterator(int) listIterator} methods are <em>fail-fast</em>:

 * if the vector is structurally modified at any time after the iterator is

 * created, in any way except through the iterator's own

 * {@link ListIterator#remove() remove} or

 * {@link ListIterator#add(Object) add} methods, the iterator will throw a

 * {@link ConcurrentModificationException}.  Thus, in the face of

 * concurrent modification, the iterator fails quickly and cleanly, rather

 * than risking arbitrary, non-deterministic behavior at an undetermined

 * time in the future.  The {@link Enumeration Enumerations} returned by

 * the {@link #elements() elements} method are <em>not</em> fail-fast.

 *

 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed

 * as it is, generally speaking, impossible to make any hard guarantees in the

 * presence of unsynchronized concurrent modification.  Fail-fast iterators

 * throw {@code ConcurrentModificationException} on a best-effort basis.

 * Therefore, it would be wrong to write a program that depended on this

 * exception for its correctness:  <i>the fail-fast behavior of iterators

 * should be used only to detect bugs.</i>

 *

 * <p>As of the Java 2 platform v1.2, this class was retrofitted to

 * implement the {@link List} interface, making it a member of the

 * <a href="{@docRoot}/../technotes/guides/collections/index.html">

 * Java Collections Framework</a>.  Unlike the new collection

 * implementations, {@code Vector} is synchronized.  If a thread-safe

 * implementation is not needed, it is recommended to use {@link

 * ArrayList} in place of {@code Vector}.

 *

 * @author  Lee Boynton

 * @author  Jonathan Payne

 * @see Collection

 * @see LinkedList

 * @since   JDK1.0

 */

public class Vector<E>

    extends AbstractList<E>

    implements List<E>, RandomAccess, Cloneable, java.io.Serializable

{

    /**

     * The array buffer into which the components of the vector are

     * stored. The capacity of the vector is the length of this array buffer,

     * and is at least large enough to contain all the vector's elements.

     *

     * <p>Any array elements following the last element in the Vector are null.

     *

     * @serial

     */

    protected Object[] elementData;

    /**

     * The number of valid components in this {@code Vector} object.

     * Components {@code elementData[0]} through

     * {@code elementData[elementCount-1]} are the actual items.

     *

     * @serial

     */

    protected int elementCount;

    /**

     * The amount by which the capacity of the vector is automatically

     * incremented when its size becomes greater than its capacity.  If

     * the capacity increment is less than or equal to zero, the capacity

     * of the vector is doubled each time it needs to grow.

     *

     * @serial

     */

    protected int capacityIncrement;

    /** use serialVersionUID from JDK 1.0.2 for interoperability */

    private static final long serialVersionUID = -2767605614048989439L;

    /**

     * Constructs an empty vector with the specified initial capacity and

     * capacity increment.

     *

     * @param   initialCapacity     the initial capacity of the vector

     * @param   capacityIncrement   the amount by which the capacity is

     *                              increased when the vector overflows

     * @throws IllegalArgumentException if the specified initial capacity

     *         is negative

     */

    public Vector(int initialCapacity, int capacityIncrement) {

        super();

        if (initialCapacity < 0)

            throw new IllegalArgumentException("Illegal Capacity: "+

                                               initialCapacity);

        this.elementData = new Object[initialCapacity];

        this.capacityIncrement = capacityIncrement;

    }

    /**

     * Constructs an empty vector with the specified initial capacity and

     * with its capacity increment equal to zero.

     *

     * @param   initialCapacity   the initial capacity of the vector

     * @throws IllegalArgumentException if the specified initial capacity

     *         is negative

     */

    public Vector(int initialCapacity) {

        this(initialCapacity, 0);

    }

    /**

     * Constructs an empty vector so that its internal data array

     * has size {@code 10} and its standard capacity increment is

     * zero.

     */

    public Vector() {

        this(10);

    }

    /**

     * Constructs a vector containing the elements of the specified

     * collection, in the order they are returned by the collection's

     * iterator.

     *

     * @param c the collection whose elements are to be placed into this

     *       vector

     * @throws NullPointerException if the specified collection is null

     * @since   1.2

     */

    public Vector(Collection<? extends E> c) {

        elementData = c.toArray();

        elementCount = elementData.length;

        // c.toArray might (incorrectly) not return Object[] (see 6260652)

        if (elementData.getClass() != Object[].class)

            elementData = Arrays.copyOf(elementData, elementCount, Object[].class);

    }

    /**

     * Copies the components of this vector into the specified array.

     * The item at index {@code k} in this vector is copied into

     * component {@code k} of {@code anArray}.

     *

     * @param  anArray the array into which the components get copied

     * @throws NullPointerException if the given array is null

     * @throws IndexOutOfBoundsException if the specified array is not

     *         large enough to hold all the components of this vector

     * @throws ArrayStoreException if a component of this vector is not of

     *         a runtime type that can be stored in the specified array

     * @see #toArray(Object[])

     */

    public synchronized void copyInto(Object[] anArray) {

        System.arraycopy(elementData, 0, anArray, 0, elementCount);

    }

    /**

     * Trims the capacity of this vector to be the vector's current

     * size. If the capacity of this vector is larger than its current

     * size, then the capacity is changed to equal the size by replacing

     * its internal data array, kept in the field {@code elementData},

     * with a smaller one. An application can use this operation to

     * minimize the storage of a vector.

     */

    public synchronized void trimToSize() {

        modCount++;

        int oldCapacity = elementData.length;

        if (elementCount < oldCapacity) {

            elementData = Arrays.copyOf(elementData, elementCount);

        }

    }

    /**

     * Increases the capacity of this vector, if necessary, to ensure

     * that it can hold at least the number of components specified by

     * the minimum capacity argument.

     *

     * <p>If the current capacity of this vector is less than

     * {@code minCapacity}, then its capacity is increased by replacing its

     * internal data array, kept in the field {@code elementData}, with a

     * larger one.  The size of the new data array will be the old size plus

     * {@code capacityIncrement}, unless the value of

     * {@code capacityIncrement} is less than or equal to zero, in which case

     * the new capacity will be twice the old capacity; but if this new size

     * is still smaller than {@code minCapacity}, then the new capacity will

     * be {@code minCapacity}.

     *

     * @param minCapacity the desired minimum capacity

     */

    public synchronized void ensureCapacity(int minCapacity) {

        if (minCapacity > 0) {

            modCount++;

            ensureCapacityHelper(minCapacity);

        }

    }

    /**

     * This implements the unsynchronized semantics of ensureCapacity.

     * Synchronized methods in this class can internally call this

     * method for ensuring capacity without incurring the cost of an

     * extra synchronization.

     *

     * @see #ensureCapacity(int)

     */

    private void ensureCapacityHelper(int minCapacity) {

        // overflow-conscious code

        if (minCapacity - elementData.length > 0)

            grow(minCapacity);

    }

    /**

     * The maximum size of array to allocate.

     * Some VMs reserve some header words in an array.

     * Attempts to allocate larger arrays may result in

     * OutOfMemoryError: Requested array size exceeds VM limit

     */

    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

    private void grow(int minCapacity) {

        // overflow-conscious code

        int oldCapacity = elementData.length;

        int newCapacity = oldCapacity + ((capacityIncrement > 0) ?

                                         capacityIncrement : oldCapacity);

        if (newCapacity - minCapacity < 0)

            newCapacity = minCapacity;

        if (newCapacity - MAX_ARRAY_SIZE > 0)

            newCapacity = hugeCapacity(minCapacity);

        elementData = Arrays.copyOf(elementData, newCapacity);

    }

    private static int hugeCapacity(int minCapacity) {

        if (minCapacity < 0) // overflow

            throw new OutOfMemoryError();

        return (minCapacity > MAX_ARRAY_SIZE) ?

            Integer.MAX_VALUE :

            MAX_ARRAY_SIZE;

    }

    /**

     * Sets the size of this vector. If the new size is greater than the

     * current size, new {@code null} items are added to the end of

     * the vector. If the new size is less than the current size, all

     * components at index {@code newSize} and greater are discarded.

     *

     * @param  newSize   the new size of this vector

     * @throws ArrayIndexOutOfBoundsException if the new size is negative

     */

    public synchronized void setSize(int newSize) {

        modCount++;

        if (newSize > elementCount) {

            ensureCapacityHelper(newSize);

        } else {

            for (int i = newSize ; i < elementCount ; i++) {

                elementData[i] = null;

            }

        }

        elementCount = newSize;

    }

    /**

     * Returns the current capacity of this vector.

     *

     * @return  the current capacity (the length of its internal

     *          data array, kept in the field {@code elementData}

     *          of this vector)

     */

    public synchronized int capacity() {

        return elementData.length;

    }

    /**

     * Returns the number of components in this vector.

     *

     * @return  the number of components in this vector

     */

    public synchronized int size() {

        return elementCount;

    }

    /**

     * Tests if this vector has no components.

     *

     * @return  {@code true} if and only if this vector has

     *          no components, that is, its size is zero;

     *          {@code false} otherwise.

     */

    public synchronized boolean isEmpty() {

        return elementCount == 0;

    }

    /**

     * Returns an enumeration of the components of this vector. The

     * returned {@code Enumeration} object will generate all items in

     * this vector. The first item generated is the item at index {@code 0},

     * then the item at index {@code 1}, and so on.

     *

     * @return  an enumeration of the components of this vector

     * @see     Iterator

     */

    public Enumeration<E> elements() {

        return new Enumeration<E>() {

            int count = 0;

            public boolean hasMoreElements() {

                return count < elementCount;

            }

            public E nextElement() {

                synchronized (Vector.this) {

                    if (count < elementCount) {

                        return elementData(count++);

                    }

                }

                throw new NoSuchElementException("Vector Enumeration");

            }

        };

    }

    /**

     * Returns {@code true} if this vector contains the specified element.

     * More formally, returns {@code true} if and only if this vector

     * contains at least one element {@code e} such that

     * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.

     *

     * @param o element whose presence in this vector is to be tested

     * @return {@code true} if this vector contains the specified element

     */

    public boolean contains(Object o) {

        return indexOf(o, 0) >= 0;

    }

    /**

     * Returns the index of the first occurrence of the specified element

     * in this vector, or -1 if this vector does not contain the element.

     * More formally, returns the lowest index {@code i} such that

     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,

     * or -1 if there is no such index.

     *

     * @param o element to search for

     * @return the index of the first occurrence of the specified element in

     *         this vector, or -1 if this vector does not contain the element

     */

    public int indexOf(Object o) {

        return indexOf(o, 0);

    }

    /**

     * Returns the index of the first occurrence of the specified element in

     * this vector, searching forwards from {@code index}, or returns -1 if

     * the element is not found.

     * More formally, returns the lowest index {@code i} such that

     * <tt>(i&nbsp;&gt;=&nbsp;index&nbsp;&amp;&amp;&nbsp;(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i))))</tt>,

     * or -1 if there is no such index.

     *

     * @param o element to search for

     * @param index index to start searching from

     * @return the index of the first occurrence of the element in

     *         this vector at position {@code index} or later in the vector;

     *         {@code -1} if the element is not found.

     * @throws IndexOutOfBoundsException if the specified index is negative

     * @see     Object#equals(Object)

     */

    public synchronized int indexOf(Object o, int index) {

        if (o == null) {

            for (int i = index ; i < elementCount ; i++)

                if (elementData[i]==null)

                    return i;

        } else {

            for (int i = index ; i < elementCount ; i++)

                if (o.equals(elementData[i]))

                    return i;

        }

        return -1;

    }

    /**

     * Returns the index of the last occurrence of the specified element

     * in this vector, or -1 if this vector does not contain the element.

     * More formally, returns the highest index {@code i} such that

     * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>,

     * or -1 if there is no such index.

     *

     * @param o element to search for

     * @return the index of the last occurrence of the specified element in

     *         this vector, or -1 if this vector does not contain the element

     */

    public synchronized int lastIndexOf(Object o) {

        return lastIndexOf(o, elementCount-1);

    }

    /**

     * Returns the index of the last occurrence of the specified element in

     * this vector, searching backwards from {@code index}, or returns -1 if

     * the element is not found.

     * More formally, returns the highest index {@code i} such that

     * <tt>(i&nbsp;&lt;=&nbsp;index&nbsp;&amp;&amp;&nbsp;(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i))))</tt>,

     * or -1 if there is no such index.

     *

     * @param o element to search for

     * @param index index to start searching backwards from

     * @return the index of the last occurrence of the element at position

     *         less than or equal to {@code index} in this vector;

     *         -1 if the element is not found.

     * @throws IndexOutOfBoundsException if the specified index is greater

     *         than or equal to the current size of this vector

     */

    public synchronized int lastIndexOf(Object o, int index) {

        if (index >= elementCount)

            throw new IndexOutOfBoundsException(index + " >= "+ elementCount);

        if (o == null) {

            for (int i = index; i >= 0; i--)

                if (elementData[i]==null)

                    return i;

        } else {

            for (int i = index; i >= 0; i--)

                if (o.equals(elementData[i]))

                    return i;

        }

        return -1;

    }

    /**

     * Returns the component at the specified index.

     *

     * <p>This method is identical in functionality to the {@link #get(int)}

     * method (which is part of the {@link List} interface).

     *

     * @param      index   an index into this vector

     * @return     the component at the specified index

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index >= size()})

     */

    public synchronized E elementAt(int index) {

        if (index >= elementCount) {

            throw new ArrayIndexOutOfBoundsException(index + " >= " + elementCount);

        }

        return elementData(index);

    }

    /**

     * Returns the first component (the item at index {@code 0}) of

     * this vector.

     *

     * @return     the first component of this vector

     * @throws NoSuchElementException if this vector has no components

     */

    public synchronized E firstElement() {

        if (elementCount == 0) {

            throw new NoSuchElementException();

        }

        return elementData(0);

    }

    /**

     * Returns the last component of the vector.

     *

     * @return  the last component of the vector, i.e., the component at index

     *          <code>size()&nbsp;-&nbsp;1</code>.

     * @throws NoSuchElementException if this vector is empty

     */

    public synchronized E lastElement() {

        if (elementCount == 0) {

            throw new NoSuchElementException();

        }

        return elementData(elementCount - 1);

    }

    /**

     * Sets the component at the specified {@code index} of this

     * vector to be the specified object. The previous component at that

     * position is discarded.

     *

     * <p>The index must be a value greater than or equal to {@code 0}

     * and less than the current size of the vector.

     *

     * <p>This method is identical in functionality to the

     * {@link #set(int, Object) set(int, E)}

     * method (which is part of the {@link List} interface). Note that the

     * {@code set} method reverses the order of the parameters, to more closely

     * match array usage.  Note also that the {@code set} method returns the

     * old value that was stored at the specified position.

     *

     * @param      obj     what the component is to be set to

     * @param      index   the specified index

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index >= size()})

     */

    public synchronized void setElementAt(E obj, int index) {

        if (index >= elementCount) {

            throw new ArrayIndexOutOfBoundsException(index + " >= " +

                                                     elementCount);

        }

        elementData[index] = obj;

    }

    /**

     * Deletes the component at the specified index. Each component in

     * this vector with an index greater or equal to the specified

     * {@code index} is shifted downward to have an index one

     * smaller than the value it had previously. The size of this vector

     * is decreased by {@code 1}.

     *

     * <p>The index must be a value greater than or equal to {@code 0}

     * and less than the current size of the vector.

     *

     * <p>This method is identical in functionality to the {@link #remove(int)}

     * method (which is part of the {@link List} interface).  Note that the

     * {@code remove} method returns the old value that was stored at the

     * specified position.

     *

     * @param      index   the index of the object to remove

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index >= size()})

     */

    public synchronized void removeElementAt(int index) {

        modCount++;

        if (index >= elementCount) {

            throw new ArrayIndexOutOfBoundsException(index + " >= " +

                                                     elementCount);

        }

        else if (index < 0) {

            throw new ArrayIndexOutOfBoundsException(index);

        }

        int j = elementCount - index - 1;

        if (j > 0) {

            System.arraycopy(elementData, index + 1, elementData, index, j);

        }

        elementCount--;

        elementData[elementCount] = null; /* to let gc do its work */

    }

    /**

     * Inserts the specified object as a component in this vector at the

     * specified {@code index}. Each component in this vector with

     * an index greater or equal to the specified {@code index} is

     * shifted upward to have an index one greater than the value it had

     * previously.

     *

     * <p>The index must be a value greater than or equal to {@code 0}

     * and less than or equal to the current size of the vector. (If the

     * index is equal to the current size of the vector, the new element

     * is appended to the Vector.)

     *

     * <p>This method is identical in functionality to the

     * {@link #add(int, Object) add(int, E)}

     * method (which is part of the {@link List} interface).  Note that the

     * {@code add} method reverses the order of the parameters, to more closely

     * match array usage.

     *

     * @param      obj     the component to insert

     * @param      index   where to insert the new component

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index > size()})

     */

    public synchronized void insertElementAt(E obj, int index) {

        modCount++;

        if (index > elementCount) {

            throw new ArrayIndexOutOfBoundsException(index

                                                     + " > " + elementCount);

        }

        ensureCapacityHelper(elementCount + 1);

        System.arraycopy(elementData, index, elementData, index + 1, elementCount - index);

        elementData[index] = obj;

        elementCount++;

    }

    /**

     * Adds the specified component to the end of this vector,

     * increasing its size by one. The capacity of this vector is

     * increased if its size becomes greater than its capacity.

     *

     * <p>This method is identical in functionality to the

     * {@link #add(Object) add(E)}

     * method (which is part of the {@link List} interface).

     *

     * @param   obj   the component to be added

     */

    public synchronized void addElement(E obj) {

        modCount++;

        ensureCapacityHelper(elementCount + 1);

        elementData[elementCount++] = obj;

    }

    /**

     * Removes the first (lowest-indexed) occurrence of the argument

     * from this vector. If the object is found in this vector, each

     * component in the vector with an index greater or equal to the

     * object's index is shifted downward to have an index one smaller

     * than the value it had previously.

     *

     * <p>This method is identical in functionality to the

     * {@link #remove(Object)} method (which is part of the

     * {@link List} interface).

     *

     * @param   obj   the component to be removed

     * @return  {@code true} if the argument was a component of this

     *          vector; {@code false} otherwise.

     */

    public synchronized boolean removeElement(Object obj) {

        modCount++;

        int i = indexOf(obj);

        if (i >= 0) {

            removeElementAt(i);

            return true;

        }

        return false;

    }

    /**

     * Removes all components from this vector and sets its size to zero.

     *

     * <p>This method is identical in functionality to the {@link #clear}

     * method (which is part of the {@link List} interface).

     */

    public synchronized void removeAllElements() {

        modCount++;

        // Let gc do its work

        for (int i = 0; i < elementCount; i++)

            elementData[i] = null;

        elementCount = 0;

    }

    /**

     * Returns a clone of this vector. The copy will contain a

     * reference to a clone of the internal data array, not a reference

     * to the original internal data array of this {@code Vector} object.

     *

     * @return  a clone of this vector

     */

    public synchronized Object clone() {

        try {

            @SuppressWarnings("unchecked")

                Vector<E> v = (Vector<E>) super.clone();

            v.elementData = Arrays.copyOf(elementData, elementCount);

            v.modCount = 0;

            return v;

        } catch (CloneNotSupportedException e) {

            // this shouldn't happen, since we are Cloneable

            throw new InternalError();

        }

    }

    /**

     * Returns an array containing all of the elements in this Vector

     * in the correct order.

     *

     * @since 1.2

     */

    public synchronized Object[] toArray() {

        return Arrays.copyOf(elementData, elementCount);

    }

    /**

     * Returns an array containing all of the elements in this Vector in the

     * correct order; the runtime type of the returned array is that of the

     * specified array.  If the Vector fits in the specified array, it is

     * returned therein.  Otherwise, a new array is allocated with the runtime

     * type of the specified array and the size of this Vector.

     *

     * <p>If the Vector fits in the specified array with room to spare

     * (i.e., the array has more elements than the Vector),

     * the element in the array immediately following the end of the

     * Vector is set to null.  (This is useful in determining the length

     * of the Vector <em>only</em> if the caller knows that the Vector

     * does not contain any null elements.)

     *

     * @param a the array into which the elements of the Vector are to

     *          be stored, if it is big enough; otherwise, a new array of the

     *          same runtime type is allocated for this purpose.

     * @return an array containing the elements of the Vector

     * @throws ArrayStoreException if the runtime type of a is not a supertype

     * of the runtime type of every element in this Vector

     * @throws NullPointerException if the given array is null

     * @since 1.2

     */

    @SuppressWarnings("unchecked")

    public synchronized <T> T[] toArray(T[] a) {

        if (a.length < elementCount)

            return (T[]) Arrays.copyOf(elementData, elementCount, a.getClass());

        System.arraycopy(elementData, 0, a, 0, elementCount);

        if (a.length > elementCount)

            a[elementCount] = null;

        return a;

    }

    // Positional Access Operations

    @SuppressWarnings("unchecked")

    E elementData(int index) {

        return (E) elementData[index];

    }

    /**

     * Returns the element at the specified position in this Vector.

     *

     * @param index index of the element to return

     * @return object at the specified index

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *            ({@code index < 0 || index >= size()})

     * @since 1.2

     */

    public synchronized E get(int index) {

        if (index >= elementCount)

            throw new ArrayIndexOutOfBoundsException(index);

        return elementData(index);

    }

    /**

     * Replaces the element at the specified position in this Vector with the

     * specified element.

     *

     * @param index index of the element to replace

     * @param element element to be stored at the specified position

     * @return the element previously at the specified position

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index >= size()})

     * @since 1.2

     */

    public synchronized E set(int index, E element) {

        if (index >= elementCount)

            throw new ArrayIndexOutOfBoundsException(index);

        E oldValue = elementData(index);

        elementData[index] = element;

        return oldValue;

    }

    /**

     * Appends the specified element to the end of this Vector.

     *

     * @param e element to be appended to this Vector

     * @return {@code true} (as specified by {@link Collection#add})

     * @since 1.2

     */

    public synchronized boolean add(E e) {

        modCount++;

        ensureCapacityHelper(elementCount + 1);

        elementData[elementCount++] = e;

        return true;

    }

    /**

     * Removes the first occurrence of the specified element in this Vector

     * If the Vector does not contain the element, it is unchanged.  More

     * formally, removes the element with the lowest index i such that

     * {@code (o==null ? get(i)==null : o.equals(get(i)))} (if such

     * an element exists).

     *

     * @param o element to be removed from this Vector, if present

     * @return true if the Vector contained the specified element

     * @since 1.2

     */

    public boolean remove(Object o) {

        return removeElement(o);

    }

    /**

     * Inserts the specified element at the specified position in this Vector.

     * Shifts the element currently at that position (if any) and any

     * subsequent elements to the right (adds one to their indices).

     *

     * @param index index at which the specified element is to be inserted

     * @param element element to be inserted

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index > size()})

     * @since 1.2

     */

    public void add(int index, E element) {

        insertElementAt(element, index);

    }

    /**

     * Removes the element at the specified position in this Vector.

     * Shifts any subsequent elements to the left (subtracts one from their

     * indices).  Returns the element that was removed from the Vector.

     *

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index >= size()})

     * @param index the index of the element to be removed

     * @return element that was removed

     * @since 1.2

     */

    public synchronized E remove(int index) {

        modCount++;

        if (index >= elementCount)

            throw new ArrayIndexOutOfBoundsException(index);

        E oldValue = elementData(index);

        int numMoved = elementCount - index - 1;

        if (numMoved > 0)

            System.arraycopy(elementData, index+1, elementData, index,

                             numMoved);

        elementData[--elementCount] = null; // Let gc do its work

        return oldValue;

    }

    /**

     * Removes all of the elements from this Vector.  The Vector will

     * be empty after this call returns (unless it throws an exception).

     *

     * @since 1.2

     */

    public void clear() {

        removeAllElements();

    }

    // Bulk Operations

    /**

     * Returns true if this Vector contains all of the elements in the

     * specified Collection.

     *

     * @param   c a collection whose elements will be tested for containment

     *          in this Vector

     * @return true if this Vector contains all of the elements in the

     *         specified collection

     * @throws NullPointerException if the specified collection is null

     */

    public synchronized boolean containsAll(Collection<?> c) {

        return super.containsAll(c);

    }

    /**

     * Appends all of the elements in the specified Collection to the end of

     * this Vector, in the order that they are returned by the specified

     * Collection's Iterator.  The behavior of this operation is undefined if

     * the specified Collection is modified while the operation is in progress.

     * (This implies that the behavior of this call is undefined if the

     * specified Collection is this Vector, and this Vector is nonempty.)

     *

     * @param c elements to be inserted into this Vector

     * @return {@code true} if this Vector changed as a result of the call

     * @throws NullPointerException if the specified collection is null

     * @since 1.2

     */

    public synchronized boolean addAll(Collection<? extends E> c) {

        modCount++;

        Object[] a = c.toArray();

        int numNew = a.length;

        ensureCapacityHelper(elementCount + numNew);

        System.arraycopy(a, 0, elementData, elementCount, numNew);

        elementCount += numNew;

        return numNew != 0;

    }

    /**

     * Removes from this Vector all of its elements that are contained in the

     * specified Collection.

     *

     * @param c a collection of elements to be removed from the Vector

     * @return true if this Vector changed as a result of the call

     * @throws ClassCastException if the types of one or more elements

     *         in this vector are incompatible with the specified

     *         collection

     * (<a href="Collection.html#optional-restrictions">optional</a>)

     * @throws NullPointerException if this vector contains one or more null

     *         elements and the specified collection does not support null

     *         elements

     * (<a href="Collection.html#optional-restrictions">optional</a>),

     *         or if the specified collection is null

     * @since 1.2

     */

    public synchronized boolean removeAll(Collection<?> c) {

        return super.removeAll(c);

    }

    /**

     * Retains only the elements in this Vector that are contained in the

     * specified Collection.  In other words, removes from this Vector all

     * of its elements that are not contained in the specified Collection.

     *

     * @param c a collection of elements to be retained in this Vector

     *          (all other elements are removed)

     * @return true if this Vector changed as a result of the call

     * @throws ClassCastException if the types of one or more elements

     *         in this vector are incompatible with the specified

     *         collection

     * (<a href="Collection.html#optional-restrictions">optional</a>)

     * @throws NullPointerException if this vector contains one or more null

     *         elements and the specified collection does not support null

     *         elements

     *         (<a href="Collection.html#optional-restrictions">optional</a>),

     *         or if the specified collection is null

     * @since 1.2

     */

    public synchronized boolean retainAll(Collection<?> c) {

        return super.retainAll(c);

    }

    /**

     * Inserts all of the elements in the specified Collection into this

     * Vector at the specified position.  Shifts the element currently at

     * that position (if any) and any subsequent elements to the right

     * (increases their indices).  The new elements will appear in the Vector

     * in the order that they are returned by the specified Collection's

     * iterator.

     *

     * @param index index at which to insert the first element from the

     *              specified collection

     * @param c elements to be inserted into this Vector

     * @return {@code true} if this Vector changed as a result of the call

     * @throws ArrayIndexOutOfBoundsException if the index is out of range

     *         ({@code index < 0 || index > size()})

     * @throws NullPointerException if the specified collection is null

     * @since 1.2

     */

    public synchronized boolean addAll(int index, Collection<? extends E> c) {

        modCount++;

        if (index < 0 || index > elementCount)

            throw new ArrayIndexOutOfBoundsException(index);

        Object[] a = c.toArray();

        int numNew = a.length;

        ensureCapacityHelper(elementCount + numNew);

        int numMoved = elementCount - index;

        if (numMoved > 0)

            System.arraycopy(elementData, index, elementData, index + numNew,

                             numMoved);

        System.arraycopy(a, 0, elementData, index, numNew);

        elementCount += numNew;

        return numNew != 0;

    }

    /**

     * Compares the specified Object with this Vector for equality.  Returns

     * true if and only if the specified Object is also a List, both Lists

     * have the same size, and all corresponding pairs of elements in the two

     * Lists are <em>equal</em>.  (Two elements {@code e1} and

     * {@code e2} are <em>equal</em> if {@code (e1==null ? e2==null :

     * e1.equals(e2))}.)  In other words, two Lists are defined to be

     * equal if they contain the same elements in the same order.

     *

     * @param o the Object to be compared for equality with this Vector

     * @return true if the specified Object is equal to this Vector

     */

    public synchronized boolean equals(Object o) {

        return super.equals(o);

    }

    /**

     * Returns the hash code value for this Vector.

     */

    public synchronized int hashCode() {

        return super.hashCode();

    }

    /**

     * Returns a string representation of this Vector, containing

     * the String representation of each element.