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

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

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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) {