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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * 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
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   *
   * 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
   * version 2 for more details (a copy is included in the LICENSE file that
   * 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;
  
  import java.util.function.Consumer;
  import java.util.function.Predicate;
  import java.util.function.UnaryOperator;
  
  /**
   * 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></a>:
   * 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(e);
          }
      }
  
      /**
       * 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.
       */
      public synchronized String toString() {
          return super.toString();
      }
  
      /**
       * Returns a view of the portion of this List between fromIndex,
       * inclusive, and toIndex, exclusive.  (If fromIndex and toIndex are
       * equal, the returned List is empty.)  The returned List is backed by this
       * List, so changes in the returned List are reflected in this List, and
       * vice-versa.  The returned List supports all of the optional List
       * operations supported by this List.
       *
       * <p>This method eliminates the need for explicit range operations (of
       * the sort that commonly exist for arrays).  Any operation that expects
       * a List can be used as a range operation by operating on a subList view
       * instead of a whole List.  For example, the following idiom
       * removes a range of elements from a List:
       * <pre>
       *      list.subList(from, to).clear();
       * </pre>
       * Similar idioms may be constructed for indexOf and lastIndexOf,
       * and all of the algorithms in the Collections class can be applied to
       * a subList.
       *
       * <p>The semantics of the List returned by this method become undefined if
       * the backing list (i.e., this List) is <i>structurally modified</i> in
       * any way other than via the returned List.  (Structural modifications are
       * those that change the size of the List, or otherwise perturb it in such
       * a fashion that iterations in progress may yield incorrect results.)
       *
       * @param fromIndex low endpoint (inclusive) of the subList
       * @param toIndex high endpoint (exclusive) of the subList
       * @return a view of the specified range within this List
       * @throws IndexOutOfBoundsException if an endpoint index value is out of range
       *         {@code (fromIndex < 0 || toIndex > size)}
       * @throws IllegalArgumentException if the endpoint indices are out of order
       *         {@code (fromIndex > toIndex)}
       */
      public synchronized List<E> subList(int fromIndex, int toIndex) {
          return Collections.synchronizedList(super.subList(fromIndex, toIndex),
                                              this);
      }
  
      /**
       * Removes from this list all of the elements whose index is between
       * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.
       * Shifts any succeeding elements to the left (reduces their index).
       * This call shortens the list by {@code (toIndex - fromIndex)} elements.
       * (If {@code toIndex==fromIndex}, this operation has no effect.)
       */
      protected synchronized void removeRange(int fromIndex, int toIndex) {
          modCount++;
          int numMoved = elementCount - toIndex;
          System.arraycopy(elementData, toIndex, elementData, fromIndex,
                           numMoved);
  
          // Let gc do its work
          int newElementCount = elementCount - (toIndex-fromIndex);
          while (elementCount != newElementCount)
              elementData[--elementCount] = null;
      }
  
      /**
       * Save the state of the {@code Vector} instance to a stream (that
       * is, serialize it).
       * This method performs synchronization to ensure the consistency
       * of the serialized data.
       */
      private void writeObject(java.io.ObjectOutputStream s)
              throws java.io.IOException {
          final java.io.ObjectOutputStream.PutField fields = s.putFields();
          final Object[] data;
          synchronized (this) {
              fields.put("capacityIncrement", capacityIncrement);
              fields.put("elementCount", elementCount);
              data = elementData.clone();
          }
          fields.put("elementData", data);
          s.writeFields();
      }
  
      /**
       * Returns a list iterator over the elements in this list (in proper
       * sequence), starting at the specified position in the list.
       * The specified index indicates the first element that would be
       * returned by an initial call to {@link ListIterator#next next}.
       * An initial call to {@link ListIterator#previous previous} would
       * return the element with the specified index minus one.
       *
       * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
       *
       * @throws IndexOutOfBoundsException {@inheritDoc}
       */
      public synchronized ListIterator<E> listIterator(int index) {
          if (index < 0 || index > elementCount)
              throw new IndexOutOfBoundsException("Index: "+index);
          return new ListItr(index);
      }
  
      /**
       * Returns a list iterator over the elements in this list (in proper
       * sequence).
       *
       * <p>The returned list iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
       *
       * @see #listIterator(int)
       */
      public synchronized ListIterator<E> listIterator() {
          return new ListItr(0);
      }
  
      /**
       * Returns an iterator over the elements in this list in proper sequence.
       *
       * <p>The returned iterator is <a href="#fail-fast"><i>fail-fast</i></a>.
       *
       * @return an iterator over the elements in this list in proper sequence
       */
      public synchronized Iterator<E> iterator() {
          return new Itr();
      }
  
      /**
       * An optimized version of AbstractList.Itr
       */
      private class Itr implements Iterator<E> {
          // Android-added: Change CME behavior: Use added limit field, not elementCount.
          // http://b/27430229 AOSP commit 6e5b758a4438d2c154dd11a5c04d14a5d2fc907c
          //
          // The "limit" of this iterator. This is the size of the list at the time the
          // iterator was created. Adding & removing elements will invalidate the iteration
          // anyway (and cause next() to throw) so saving this value will guarantee that the
          // value of hasNext() remains stable and won't flap between true and false when elements
          // are added and removed from the list.
          protected int limit = Vector.this.elementCount;
  
          int cursor;       // index of next element to return
          int lastRet = -1; // index of last element returned; -1 if no such
          int expectedModCount = modCount;
  
          public boolean hasNext() {
              // Android-changed: Change CME behavior: Use added limit field, not elementCount.
              // return cursor != elementCount;
              return cursor < limit;
          }
  
          public E next() {
              synchronized (Vector.this) {
                  checkForComodification();
                  int i = cursor;
                  // Android-changed: Change CME behavior: Use added limit field, not elementCount.
                  // if (i >= elementCount)
                  if (i >= limit)
                      throw new NoSuchElementException();
                  cursor = i + 1;
                  return elementData(lastRet = i);
              }
          }
  
          public void remove() {
              if (lastRet == -1)
                  throw new IllegalStateException();
              synchronized (Vector.this) {
                  checkForComodification();
                  Vector.this.remove(lastRet);
                  expectedModCount = modCount;
                  // Android-added: Change CME behavior: Use added limit field, not elementCount.
                  limit--;
              }
              cursor = lastRet;
              lastRet = -1;
          }
  
          @Override
          public void forEachRemaining(Consumer<? super E> action) {
              Objects.requireNonNull(action);
              synchronized (Vector.this) {
                  // Android-changed: Change CME behavior: Use added limit field, not elementCount.
                  // final int size = elementCount;
                  final int size = limit;
                  int i = cursor;
                  if (i >= size) {
                      return;
                  }
          @SuppressWarnings("unchecked")
                  final E[] elementData = (E[]) Vector.this.elementData;
                  if (i >= elementData.length) {
                      throw new ConcurrentModificationException();
                  }
                  while (i != size && modCount == expectedModCount) {
                      action.accept(elementData[i++]);
                  }
                  // update once at end of iteration to reduce heap write traffic
                  cursor = i;
                  lastRet = i - 1;
                  checkForComodification();
              }
          }
  
          final void checkForComodification() {
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
          }
      }
  
      /**
       * An optimized version of AbstractList.ListItr
       */
      final class ListItr extends Itr implements ListIterator<E> {
          ListItr(int index) {
              super();
              cursor = index;
          }
  
          public boolean hasPrevious() {
              return cursor != 0;
          }
  
          public int nextIndex() {
              return cursor;
          }
  
          public int previousIndex() {
              return cursor - 1;
          }
  
          public E previous() {
              synchronized (Vector.this) {
                  checkForComodification();
                  int i = cursor - 1;
                  if (i < 0)
                      throw new NoSuchElementException();
                  cursor = i;
                  return elementData(lastRet = i);
              }
          }
  
          public void set(E e) {
              if (lastRet == -1)
                  throw new IllegalStateException();
              synchronized (Vector.this) {
                  checkForComodification();
                  Vector.this.set(lastRet, e);
              }
          }
  
          public void add(E e) {
              int i = cursor;
              synchronized (Vector.this) {
                  checkForComodification();
                  Vector.this.add(i, e);
                  expectedModCount = modCount;
                  // Android-added: Change CME behavior: Use added limit field, not elementCount.
                  limit++;
              }
              cursor = i + 1;
              lastRet = -1;
          }
      }
  
      @Override
      public synchronized void forEach(Consumer<? super E> action) {
          Objects.requireNonNull(action);
          final int expectedModCount = modCount;
          @SuppressWarnings("unchecked")
          final E[] elementData = (E[]) this.elementData;
          final int elementCount = this.elementCount;
          for (int i=0; modCount == expectedModCount && i < elementCount; i++) {
              action.accept(elementData[i]);
          }
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public synchronized boolean removeIf(Predicate<? super E> filter) {
          Objects.requireNonNull(filter);
          // figure out which elements are to be removed
          // any exception thrown from the filter predicate at this stage
          // will leave the collection unmodified
          int removeCount = 0;
          final int size = elementCount;
          final BitSet removeSet = new BitSet(size);
          final int expectedModCount = modCount;
          for (int i=0; modCount == expectedModCount && i < size; i++) {
              @SuppressWarnings("unchecked")
              final E element = (E) elementData[i];
              if (filter.test(element)) {
                  removeSet.set(i);
                  removeCount++;
              }
          }
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
  
          // shift surviving elements left over the spaces left by removed elements
          final boolean anyToRemove = removeCount > 0;
          if (anyToRemove) {
              final int newSize = size - removeCount;
              for (int i=0, j=0; (i < size) && (j < newSize); i++, j++) {
                  i = removeSet.nextClearBit(i);
                  elementData[j] = elementData[i];
              }
              for (int k=newSize; k < size; k++) {
                  elementData[k] = null;  // Let gc do its work
              }
              elementCount = newSize;
              if (modCount != expectedModCount) {
                  throw new ConcurrentModificationException();
              }
              modCount++;
          }
  
          return anyToRemove;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public synchronized void replaceAll(UnaryOperator<E> operator) {
          Objects.requireNonNull(operator);
          final int expectedModCount = modCount;
          final int size = elementCount;
          for (int i=0; modCount == expectedModCount && i < size; i++) {
              elementData[i] = operator.apply((E) elementData[i]);
          }
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
          modCount++;
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public synchronized void sort(Comparator<? super E> c) {
          final int expectedModCount = modCount;
          Arrays.sort((E[]) elementData, 0, elementCount, c);
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
          modCount++;
      }
  
      /**
       * Creates a <em><a href="Spliterator.html#binding">late-binding</a></em>
       * and <em>fail-fast</em> {@link Spliterator} over the elements in this
       * list.
       *
       * <p>The {@code Spliterator} reports {@link Spliterator#SIZED},
       * {@link Spliterator#SUBSIZED}, and {@link Spliterator#ORDERED}.
       * Overriding implementations should document the reporting of additional
       * characteristic values.
       *
       * @return a {@code Spliterator} over the elements in this list
       * @since 1.8
       */
      @Override
      public Spliterator<E> spliterator() {
          return new VectorSpliterator<>(this, null, 0, -1, 0);
      }
  
      /** Similar to ArrayList Spliterator */
      static final class VectorSpliterator<E> implements Spliterator<E> {
          private final Vector<E> list;
          private Object[] array;
          private int index; // current index, modified on advance/split
          private int fence; // -1 until used; then one past last index
          private int expectedModCount; // initialized when fence set
  
          /** Create new spliterator covering the given  range */
          VectorSpliterator(Vector<E> list, Object[] array, int origin, int fence,
                            int expectedModCount) {
              this.list = list;
              this.array = array;
              this.index = origin;
              this.fence = fence;
              this.expectedModCount = expectedModCount;
          }
  
          private int getFence() { // initialize on first use
              int hi;
              if ((hi = fence) < 0) {
                  synchronized(list) {
                      array = list.elementData;
                      expectedModCount = list.modCount;
                      hi = fence = list.elementCount;
                  }
              }
              return hi;
          }
  
          public Spliterator<E> trySplit() {
              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
              return (lo >= mid) ? null :
                  new VectorSpliterator<E>(list, array, lo, index = mid,
                                           expectedModCount);
          }
  
          @SuppressWarnings("unchecked")
          public boolean tryAdvance(Consumer<? super E> action) {
              int i;
              if (action == null)
                  throw new NullPointerException();
              if (getFence() > (i = index)) {
                  index = i + 1;
                  action.accept((E)array[i]);
                  if (list.modCount != expectedModCount)
                      throw new ConcurrentModificationException();
                  return true;
              }
              return false;
          }
  
          @SuppressWarnings("unchecked")
          public void forEachRemaining(Consumer<? super E> action) {
              int i, hi; // hoist accesses and checks from loop
              Vector<E> lst; Object[] a;
              if (action == null)
                  throw new NullPointerException();
              if ((lst = list) != null) {
                  if ((hi = fence) < 0) {
                      synchronized(lst) {
                          expectedModCount = lst.modCount;
                          a = array = lst.elementData;
                          hi = fence = lst.elementCount;
                      }
                  }
                  else
                      a = array;
                  if (a != null && (i = index) >= 0 && (index = hi) <= a.length) {
                      while (i < hi)
                          action.accept((E) a[i++]);
                      if (lst.modCount == expectedModCount)
                          return;
                  }
              }
              throw new ConcurrentModificationException();
          }
  
          public long estimateSize() {
              return (long) (getFence() - index);
          }
  
          public int characteristics() {
              return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
          }
      }
  }
  