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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
   * 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
   * 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
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.util;
  
  import java.util.function.UnaryOperator;
  
  // Android-removed: removed link to collections framework docs
  
  /**
   * An ordered collection (also known as a <i>sequence</i>).  The user of this
   * interface has precise control over where in the list each element is
   * inserted.  The user can access elements by their integer index (position in
   * the list), and search for elements in the list.<p>
   *
   * Unlike sets, lists typically allow duplicate elements.  More formally,
   * lists typically allow pairs of elements {@code e1} and {@code e2}
   * such that {@code e1.equals(e2)}, and they typically allow multiple
   * null elements if they allow null elements at all.  It is not inconceivable
   * that someone might wish to implement a list that prohibits duplicates, by
   * throwing runtime exceptions when the user attempts to insert them, but we
   * expect this usage to be rare.<p>
   *
   * The {@code List} interface places additional stipulations, beyond those
   * specified in the {@code Collection} interface, on the contracts of the
   * {@code iterator}, {@code add}, {@code remove}, {@code equals}, and
   * {@code hashCode} methods.  Declarations for other inherited methods are
   * also included here for convenience.<p>
   *
   * The {@code List} interface provides four methods for positional (indexed)
   * access to list elements.  Lists (like Java arrays) are zero based.  Note
   * that these operations may execute in time proportional to the index value
   * for some implementations (the {@code LinkedList} class, for
   * example). Thus, iterating over the elements in a list is typically
   * preferable to indexing through it if the caller does not know the
   * implementation.<p>
   *
   * The {@code List} interface provides a special iterator, called a
   * {@code ListIterator}, that allows element insertion and replacement, and
   * bidirectional access in addition to the normal operations that the
   * {@code Iterator} interface provides.  A method is provided to obtain a
   * list iterator that starts at a specified position in the list.<p>
   *
   * The {@code List} interface provides two methods to search for a specified
   * object.  From a performance standpoint, these methods should be used with
   * caution.  In many implementations they will perform costly linear
   * searches.<p>
   *
   * The {@code List} interface provides two methods to efficiently insert and
   * remove multiple elements at an arbitrary point in the list.<p>
   *
   * Note: While it is permissible for lists to contain themselves as elements,
   * extreme caution is advised: the {@code equals} and {@code hashCode}
   * methods are no longer well defined on such a list.
   *
   * <p>Some list implementations have restrictions on the elements that
   * they may contain.  For example, some implementations prohibit null elements,
   * and some have restrictions on the types of their elements.  Attempting to
   * add an ineligible element throws an unchecked exception, typically
   * {@code NullPointerException} or {@code ClassCastException}.  Attempting
   * to query the presence of an ineligible element may throw an exception,
   * or it may simply return false; some implementations will exhibit the former
   * behavior and some will exhibit the latter.  More generally, attempting an
   * operation on an ineligible element whose completion would not result in
   * the insertion of an ineligible element into the list may throw an
   * exception or it may succeed, at the option of the implementation.
   * Such exceptions are marked as "optional" in the specification for this
   * interface.
   *
   * <h2><a id="immutable">Immutable List Static Factory Methods</a></h2>
   * <p>The {@link List#of(Object...) List.of()} static factory methods
   * provide a convenient way to create immutable lists. The {@code List}
   * instances created by these methods have the following characteristics:
   *
   * <ul>
   * <li>They are <em>structurally immutable</em>. Elements cannot be added, removed,
   * or replaced. Calling any mutator method will always cause
   * {@code UnsupportedOperationException} to be thrown.
   * However, if the contained elements are themselves mutable,
   * this may cause the List's contents to appear to change.
   * <li>They disallow {@code null} elements. Attempts to create them with
   * {@code null} elements result in {@code NullPointerException}.
   * <li>They are serializable if all elements are serializable.
   * <li>The order of elements in the list is the same as the order of the
   * provided arguments, or of the elements in the provided array.
   * <li>They are <a href="../lang/doc-files/ValueBased.html">value-based</a>.
   * Callers should make no assumptions about the identity of the returned instances.
   * Factories are free to create new instances or reuse existing ones. Therefore,
   * identity-sensitive operations on these instances (reference equality ({@code ==}),
   * identity hash code, and synchronization) are unreliable and should be avoided.
   * <li>They are serialized as specified on the
   * <a href="{@docRoot}/serialized-form.html#java.util.CollSer">Serialized Form</a>
   * page.
   * </ul>
   *
   * @param <E> the type of elements in this list
   *
   * @author  Josh Bloch
   * @author  Neal Gafter
   * @see Collection
   * @see Set
   * @see ArrayList
   * @see LinkedList
   * @see Vector
   * @see Arrays#asList(Object[])
   * @see Collections#nCopies(int, Object)
   * @see Collections#EMPTY_LIST
   * @see AbstractList
   * @see AbstractSequentialList
   * @since 1.2
   */
  
  public interface List<E> extends Collection<E> {
      // Query Operations
  
      /**
       * Returns the number of elements in this list.  If this list contains
       * more than {@code Integer.MAX_VALUE} elements, returns
       * {@code Integer.MAX_VALUE}.
       *
       * @return the number of elements in this list
       */
      int size();
  
      /**
       * Returns {@code true} if this list contains no elements.
       *
       * @return {@code true} if this list contains no elements
       */
      boolean isEmpty();
  
      /**
       * Returns {@code true} if this list contains the specified element.
       * More formally, returns {@code true} if and only if this list contains
       * at least one element {@code e} such that
       * {@code Objects.equals(o, e)}.
       *
       * @param o element whose presence in this list is to be tested
       * @return {@code true} if this list contains the specified element
       * @throws ClassCastException if the type of the specified element
       *         is incompatible with this list
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if the specified element is null and this
       *         list does not permit null elements
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       */
      boolean contains(Object o);
  
      /**
       * Returns an iterator over the elements in this list in proper sequence.
       *
       * @return an iterator over the elements in this list in proper sequence
       */
      Iterator<E> iterator();
  
      /**
       * Returns an array containing all of the elements in this list in proper
       * sequence (from first to last element).
       *
       * <p>The returned array will be "safe" in that no references to it are
       * maintained by this list.  (In other words, this method must
       * allocate a new array even if this list is backed by an array).
       * The caller is thus free to modify the returned array.
       *
       * <p>This method acts as bridge between array-based and collection-based
       * APIs.
       *
       * @return an array containing all of the elements in this list in proper
       *         sequence
       * @see Arrays#asList(Object[])
       */
      Object[] toArray();
  
      /**
       * Returns an array containing all of the elements in this list in
       * proper sequence (from first to last element); the runtime type of
       * the returned array is that of the specified array.  If the list 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 list.
       *
       * <p>If the list fits in the specified array with room to spare (i.e.,
       * the array has more elements than the list), the element in the array
       * immediately following the end of the list is set to {@code null}.
       * (This is useful in determining the length of the list <i>only</i> if
       * the caller knows that the list does not contain any null elements.)
       *
       * <p>Like the {@link #toArray()} method, this method acts as bridge between
       * array-based and collection-based APIs.  Further, this method allows
       * precise control over the runtime type of the output array, and may,
       * under certain circumstances, be used to save allocation costs.
       *
       * <p>Suppose {@code x} is a list known to contain only strings.
       * The following code can be used to dump the list into a newly
       * allocated array of {@code String}:
       *
       * <pre>{@code
       *     String[] y = x.toArray(new String[0]);
       * }</pre>
       *
       * Note that {@code toArray(new Object[0])} is identical in function to
       * {@code toArray()}.
       *
       * @param a the array into which the elements of this list 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 this list
       * @throws ArrayStoreException if the runtime type of the specified array
       *         is not a supertype of the runtime type of every element in
       *         this list
       * @throws NullPointerException if the specified array is null
       */
      <T> T[] toArray(T[] a);
  
  
      // Modification Operations
  
      /**
       * Appends the specified element to the end of this list (optional
       * operation).
       *
       * <p>Lists that support this operation may place limitations on what
       * elements may be added to this list.  In particular, some
       * lists will refuse to add null elements, and others will impose
       * restrictions on the type of elements that may be added.  List
       * classes should clearly specify in their documentation any restrictions
       * on what elements may be added.
       *
       * @param e element to be appended to this list
       * @return {@code true} (as specified by {@link Collection#add})
       * @throws UnsupportedOperationException if the {@code add} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of the specified element
       *         prevents it from being added to this list
       * @throws NullPointerException if the specified element is null and this
       *         list does not permit null elements
       * @throws IllegalArgumentException if some property of this element
       *         prevents it from being added to this list
       */
      boolean add(E e);
  
      /**
       * Removes the first occurrence of the specified element from this list,
       * if it is present (optional operation).  If this list does not contain
       * the element, it is unchanged.  More formally, removes the element with
       * the lowest index {@code i} such that
       * {@code Objects.equals(o, get(i))}
       * (if such an element exists).  Returns {@code true} if this list
       * contained the specified element (or equivalently, if this list changed
       * as a result of the call).
       *
       * @param o element to be removed from this list, if present
       * @return {@code true} if this list contained the specified element
       * @throws ClassCastException if the type of the specified element
       *         is incompatible with this list
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if the specified element is null and this
       *         list does not permit null elements
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws UnsupportedOperationException if the {@code remove} operation
       *         is not supported by this list
       */
      boolean remove(Object o);
  
  
      // Bulk Modification Operations
  
      /**
       * Returns {@code true} if this list contains all of the elements of the
       * specified collection.
       *
       * @param  c collection to be checked for containment in this list
       * @return {@code true} if this list contains all of the elements of the
       *         specified collection
       * @throws ClassCastException if the types of one or more elements
       *         in the specified collection are incompatible with this
       *         list
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if the specified collection contains one
       *         or more null elements and this list does not permit null
       *         elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>),
       *         or if the specified collection is null
       * @see #contains(Object)
       */
      boolean containsAll(Collection<?> c);
  
      /**
       * Appends all of the elements in the specified collection to the end of
       * this list, in the order that they are returned by the specified
       * collection's iterator (optional operation).  The behavior of this
       * operation is undefined if the specified collection is modified while
       * the operation is in progress.  (Note that this will occur if the
       * specified collection is this list, and it's nonempty.)
       *
       * @param c collection containing elements to be added to this list
       * @return {@code true} if this list changed as a result of the call
       * @throws UnsupportedOperationException if the {@code addAll} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of an element of the specified
       *         collection prevents it from being added to this list
       * @throws NullPointerException if the specified collection contains one
       *         or more null elements and this list does not permit null
       *         elements, or if the specified collection is null
       * @throws IllegalArgumentException if some property of an element of the
       *         specified collection prevents it from being added to this list
       * @see #add(Object)
       */
      boolean addAll(Collection<? extends E> c);
  
      /**
       * Inserts all of the elements in the specified collection into this
       * list at the specified position (optional operation).  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 this list 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.  (Note that this will occur if the specified
       * collection is this list, and it's nonempty.)
       *
       * @param index index at which to insert the first element from the
       *              specified collection
       * @param c collection containing elements to be added to this list
       * @return {@code true} if this list changed as a result of the call
       * @throws UnsupportedOperationException if the {@code addAll} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of an element of the specified
       *         collection prevents it from being added to this list
       * @throws NullPointerException if the specified collection contains one
       *         or more null elements and this list does not permit null
       *         elements, or if the specified collection is null
       * @throws IllegalArgumentException if some property of an element of the
       *         specified collection prevents it from being added to this list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index > size()})
       */
      boolean addAll(int index, Collection<? extends E> c);
  
      /**
       * Removes from this list all of its elements that are contained in the
       * specified collection (optional operation).
       *
       * @param c collection containing elements to be removed from this list
       * @return {@code true} if this list changed as a result of the call
       * @throws UnsupportedOperationException if the {@code removeAll} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of an element of this list
       *         is incompatible with the specified collection
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if this list contains a null element and the
       *         specified collection does not permit null elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>),
       *         or if the specified collection is null
       * @see #remove(Object)
       * @see #contains(Object)
       */
      boolean removeAll(Collection<?> c);
  
      /**
       * Retains only the elements in this list that are contained in the
       * specified collection (optional operation).  In other words, removes
       * from this list all of its elements that are not contained in the
       * specified collection.
       *
       * @param c collection containing elements to be retained in this list
       * @return {@code true} if this list changed as a result of the call
       * @throws UnsupportedOperationException if the {@code retainAll} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of an element of this list
       *         is incompatible with the specified collection
       * (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if this list contains a null element and the
       *         specified collection does not permit null elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>),
       *         or if the specified collection is null
       * @see #remove(Object)
       * @see #contains(Object)
       */
      boolean retainAll(Collection<?> c);
  
      /**
       * Replaces each element of this list with the result of applying the
       * operator to that element.  Errors or runtime exceptions thrown by
       * the operator are relayed to the caller.
       *
       * @implSpec
       * The default implementation is equivalent to, for this {@code list}:
       * <pre>{@code
       *     final ListIterator<E> li = list.listIterator();
       *     while (li.hasNext()) {
       *         li.set(operator.apply(li.next()));
       *     }
       * }</pre>
       *
       * If the list's list-iterator does not support the {@code set} operation
       * then an {@code UnsupportedOperationException} will be thrown when
       * replacing the first element.
       *
       * @param operator the operator to apply to each element
       * @throws UnsupportedOperationException if this list is unmodifiable.
       *         Implementations may throw this exception if an element
       *         cannot be replaced or if, in general, modification is not
       *         supported
       * @throws NullPointerException if the specified operator is null or
       *         if the operator result is a null value and this list does
       *         not permit null elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       * @since 1.8
       */
      default void replaceAll(UnaryOperator<E> operator) {
          Objects.requireNonNull(operator);
          final ListIterator<E> li = this.listIterator();
          while (li.hasNext()) {
              li.set(operator.apply(li.next()));
          }
      }
  
      // Android-added: List.sort() vs. Collections.sort() app compat.
      // Added a warning in the documentation.
      // Collections.sort() calls List.sort() for apps targeting API version >= 26
      // (Android Oreo) but the other way around for app targeting <= 25 (Nougat).
      /**
       * Sorts this list according to the order induced by the specified
       * {@link Comparator}.
       *
       * <p>All elements in this list must be <i>mutually comparable</i> using the
       * specified comparator (that is, {@code c.compare(e1, e2)} must not throw
       * a {@code ClassCastException} for any elements {@code e1} and {@code e2}
       * in the list).
       *
       * <p>If the specified comparator is {@code null} then all elements in this
       * list must implement the {@link Comparable} interface and the elements'
       * {@linkplain Comparable natural ordering} should be used.
       *
       * <p>This list must be modifiable, but need not be resizable.
       *
       * <p>For apps running on and targeting Android versions greater than
       * Nougat (API level {@code > 25}), {@link Collections#sort(List)}
       * delegates to this method. Such apps must not call
       * {@link Collections#sort(List)} from this method. Instead, prefer
       * not overriding this method at all. If you must override it, consider
       * this implementation:
       * <pre>
       * &#064;Override
       * public void sort(Comparator&lt;? super E&gt; c) {
       *   Object[] elements = toArray();
       *   Arrays.sort(elements, c);
       *   ListIterator&lt;E&gt; iterator = (ListIterator&lt;Object&gt;) listIterator();
       *   for (Object element : elements) {
       *     iterator.next();
       *     iterator.set((E) element);
       *   }
       * }
       * </pre>
       *
       * @implSpec
       * The default implementation obtains an array containing all elements in
       * this list, sorts the array, and iterates over this list resetting each
       * element from the corresponding position in the array. (This avoids the
       * n<sup>2</sup> log(n) performance that would result from attempting
       * to sort a linked list in place.)
       *
       * @implNote
       * This implementation is a stable, adaptive, iterative mergesort that
       * requires far fewer than n lg(n) comparisons when the input array is
       * partially sorted, while offering the performance of a traditional
       * mergesort when the input array is randomly ordered.  If the input array
       * is nearly sorted, the implementation requires approximately n
       * comparisons.  Temporary storage requirements vary from a small constant
       * for nearly sorted input arrays to n/2 object references for randomly
       * ordered input arrays.
       *
       * <p>The implementation takes equal advantage of ascending and
       * descending order in its input array, and can take advantage of
       * ascending and descending order in different parts of the same
       * input array.  It is well-suited to merging two or more sorted arrays:
       * simply concatenate the arrays and sort the resulting array.
       *
       * <p>The implementation was adapted from Tim Peters's list sort for Python
       * (<a href="http://svn.python.org/projects/python/trunk/Objects/listsort.txt">
       * TimSort</a>).  It uses techniques from Peter McIlroy's "Optimistic
       * Sorting and Information Theoretic Complexity", in Proceedings of the
       * Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
       * January 1993.
       *
       * @param c the {@code Comparator} used to compare list elements.
       *          A {@code null} value indicates that the elements'
       *          {@linkplain Comparable natural ordering} should be used
       * @throws ClassCastException if the list contains elements that are not
       *         <i>mutually comparable</i> using the specified comparator
       * @throws UnsupportedOperationException if the list's list-iterator does
       *         not support the {@code set} operation
       * @throws IllegalArgumentException
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       *         if the comparator is found to violate the {@link Comparator}
       *         contract
       * @since 1.8
       */
      @SuppressWarnings({"unchecked", "rawtypes"})
      default void sort(Comparator<? super E> c) {
          Object[] a = this.toArray();
          Arrays.sort(a, (Comparator) c);
          ListIterator<E> i = this.listIterator();
          for (Object e : a) {
              i.next();
              i.set((E) e);
          }
      }
  
      /**
       * Removes all of the elements from this list (optional operation).
       * The list will be empty after this call returns.
       *
       * @throws UnsupportedOperationException if the {@code clear} operation
       *         is not supported by this list
       */
      void clear();
  
  
      // Comparison and hashing
  
      /**
       * Compares the specified object with this list for equality.  Returns
       * {@code 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 <i>equal</i>.  (Two elements {@code e1} and
       * {@code e2} are <i>equal</i> if {@code Objects.equals(e1, e2)}.)
       * In other words, two lists are defined to be
       * equal if they contain the same elements in the same order.  This
       * definition ensures that the equals method works properly across
       * different implementations of the {@code List} interface.
       *
       * @param o the object to be compared for equality with this list
       * @return {@code true} if the specified object is equal to this list
       */
      boolean equals(Object o);
  
      /**
       * Returns the hash code value for this list.  The hash code of a list
       * is defined to be the result of the following calculation:
       * <pre>{@code
       *     int hashCode = 1;
       *     for (E e : list)
       *         hashCode = 31*hashCode + (e==null ? 0 : e.hashCode());
       * }</pre>
       * This ensures that {@code list1.equals(list2)} implies that
       * {@code list1.hashCode()==list2.hashCode()} for any two lists,
       * {@code list1} and {@code list2}, as required by the general
       * contract of {@link Object#hashCode}.
       *
       * @return the hash code value for this list
       * @see Object#equals(Object)
       * @see #equals(Object)
       */
      int hashCode();
  
  
      // Positional Access Operations
  
      /**
       * Returns the element at the specified position in this list.
       *
       * @param index index of the element to return
       * @return the element at the specified position in this list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index >= size()})
       */
      E get(int index);
  
      /**
       * Replaces the element at the specified position in this list with the
       * specified element (optional operation).
       *
       * @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 UnsupportedOperationException if the {@code set} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of the specified element
       *         prevents it from being added to this list
       * @throws NullPointerException if the specified element is null and
       *         this list does not permit null elements
       * @throws IllegalArgumentException if some property of the specified
       *         element prevents it from being added to this list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index >= size()})
       */
      E set(int index, E element);
  
      /**
       * Inserts the specified element at the specified position in this list
       * (optional operation).  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 UnsupportedOperationException if the {@code add} operation
       *         is not supported by this list
       * @throws ClassCastException if the class of the specified element
       *         prevents it from being added to this list
       * @throws NullPointerException if the specified element is null and
       *         this list does not permit null elements
       * @throws IllegalArgumentException if some property of the specified
       *         element prevents it from being added to this list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index > size()})
       */
      void add(int index, E element);
  
      /**
       * Removes the element at the specified position in this list (optional
       * operation).  Shifts any subsequent elements to the left (subtracts one
       * from their indices).  Returns the element that was removed from the
       * list.
       *
       * @param index the index of the element to be removed
       * @return the element previously at the specified position
       * @throws UnsupportedOperationException if the {@code remove} operation
       *         is not supported by this list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index >= size()})
       */
      E remove(int index);
  
  
      // Search Operations
  
      /**
       * Returns the index of the first occurrence of the specified element
       * in this list, or -1 if this list does not contain the element.
       * More formally, returns the lowest index {@code i} such that
       * {@code Objects.equals(o, get(i))},
       * 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 list, or -1 if this list does not contain the element
       * @throws ClassCastException if the type of the specified element
       *         is incompatible with this list
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if the specified element is null and this
       *         list does not permit null elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       */
      int indexOf(Object o);
  
      /**
       * Returns the index of the last occurrence of the specified element
       * in this list, or -1 if this list does not contain the element.
       * More formally, returns the highest index {@code i} such that
       * {@code Objects.equals(o, get(i))},
       * 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 list, or -1 if this list does not contain the element
       * @throws ClassCastException if the type of the specified element
       *         is incompatible with this list
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       * @throws NullPointerException if the specified element is null and this
       *         list does not permit null elements
       *         (<a href="Collection.html#optional-restrictions">optional</a>)
       */
      int lastIndexOf(Object o);
  
  
      // List Iterators
  
      /**
       * Returns a list iterator over the elements in this list (in proper
       * sequence).
       *
       * @return a list iterator over the elements in this list (in proper
       *         sequence)
       */
      ListIterator<E> listIterator();
  
      /**
       * 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.
       *
       * @param index index of the first element to be returned from the
       *        list iterator (by a call to {@link ListIterator#next next})
       * @return a list iterator over the elements in this list (in proper
       *         sequence), starting at the specified position in the list
       * @throws IndexOutOfBoundsException if the index is out of range
       *         ({@code index < 0 || index > size()})
       */
      ListIterator<E> listIterator(int index);
  
      // View
  
      /**
       * Returns a view of the portion of this list between the specified
       * {@code fromIndex}, inclusive, and {@code toIndex}, exclusive.  (If
       * {@code fromIndex} and {@code toIndex} are equal, the returned list is
       * empty.)  The returned list is backed by this list, so non-structural
       * 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 passing a subList view
       * instead of a whole list.  For example, the following idiom
       * removes a range of elements from a list:
       * <pre>{@code
       *      list.subList(from, to).clear();
       * }</pre>
       * Similar idioms may be constructed for {@code indexOf} and
       * {@code lastIndexOf}, and all of the algorithms in the
       * {@code 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 this 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 for an illegal endpoint index value
       *         ({@code fromIndex < 0 || toIndex > size ||
       *         fromIndex > toIndex})
       */
      List<E> subList(int fromIndex, int toIndex);
  
      /**
       * Creates a {@link Spliterator} over the elements in this list.
       *
       * <p>The {@code Spliterator} reports {@link Spliterator#SIZED} and
       * {@link Spliterator#ORDERED}.  Implementations should document the
       * reporting of additional characteristic values.
       *
       * @implSpec
       * The default implementation creates a
       * <em><a href="Spliterator.html#binding">late-binding</a></em>
       * spliterator as follows:
       * <ul>
       * <li>If the list is an instance of {@link RandomAccess} then the default
       *     implementation creates a spliterator that traverses elements by
       *     invoking the method {@link List#get}.  If such invocation results or
       *     would result in an {@code IndexOutOfBoundsException} then the
       *     spliterator will <em>fail-fast</em> and throw a
       *     {@code ConcurrentModificationException}.
       *     If the list is also an instance of {@link AbstractList} then the
       *     spliterator will use the list's {@link AbstractList#modCount modCount}
       *     field to provide additional <em>fail-fast</em> behavior.
       * <li>Otherwise, the default implementation creates a spliterator from the
       *     list's {@code Iterator}.  The spliterator inherits the
       *     <em>fail-fast</em> of the list's iterator.
       * </ul>
       *
       * @implNote
       * The created {@code Spliterator} additionally reports
       * {@link Spliterator#SUBSIZED}.
       *
       * @return a {@code Spliterator} over the elements in this list
       * @since 1.8
       */
      @Override
      default Spliterator<E> spliterator() {
          if (this instanceof RandomAccess) {
              return new AbstractList.RandomAccessSpliterator<>(this);
          } else {
              return Spliterators.spliterator(this, Spliterator.ORDERED);
          }
      }
  
      /**
       * Returns an immutable list containing zero elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @return an empty {@code List}
       *
       * @since 9
       */
      static <E> List<E> of() {
          return ImmutableCollections.List0.instance();
      }
  
      /**
       * Returns an immutable list containing one element.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the single element
       * @return a {@code List} containing the specified element
       * @throws NullPointerException if the element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1) {
          return new ImmutableCollections.List1<>(e1);
      }
  
      /**
       * Returns an immutable list containing two elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2) {
          return new ImmutableCollections.List2<>(e1, e2);
      }
  
      /**
       * Returns an immutable list containing three elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3) {
          return new ImmutableCollections.ListN<>(e1, e2, e3);
      }
  
      /**
       * Returns an immutable list containing four elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4);
      }
  
      /**
       * Returns an immutable list containing five elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5);
      }
  
      /**
       * Returns an immutable list containing six elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @param e6 the sixth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5,
                                                  e6);
      }
  
      /**
       * Returns an immutable list containing seven elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @param e6 the sixth element
       * @param e7 the seventh element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5,
                                                  e6, e7);
      }
  
      /**
       * Returns an immutable list containing eight elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @param e6 the sixth element
       * @param e7 the seventh element
       * @param e8 the eighth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5,
                                                  e6, e7, e8);
      }
  
      /**
       * Returns an immutable list containing nine elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @param e6 the sixth element
       * @param e7 the seventh element
       * @param e8 the eighth element
       * @param e9 the ninth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5,
                                                  e6, e7, e8, e9);
      }
  
      /**
       * Returns an immutable list containing ten elements.
       *
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @param <E> the {@code List}'s element type
       * @param e1 the first element
       * @param e2 the second element
       * @param e3 the third element
       * @param e4 the fourth element
       * @param e5 the fifth element
       * @param e6 the sixth element
       * @param e7 the seventh element
       * @param e8 the eighth element
       * @param e9 the ninth element
       * @param e10 the tenth element
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null}
       *
       * @since 9
       */
      static <E> List<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E e7, E e8, E e9, E e10) {
          return new ImmutableCollections.ListN<>(e1, e2, e3, e4, e5,
                                                  e6, e7, e8, e9, e10);
      }
  
      /**
       * Returns an immutable list containing an arbitrary number of elements.
       * See <a href="#immutable">Immutable List Static Factory Methods</a> for details.
       *
       * @apiNote
       * This method also accepts a single array as an argument. The element type of
       * the resulting list will be the component type of the array, and the size of
       * the list will be equal to the length of the array. To create a list with
       * a single element that is an array, do the following:
       *
       * <pre>{@code
       *     String[] array = ... ;
       *     List<String[]> list = List.<String[]>of(array);
       * }</pre>
       *
       * This will cause the {@link List#of(Object) List.of(E)} method
       * to be invoked instead.
       *
       * @param <E> the {@code List}'s element type
       * @param elements the elements to be contained in the list
       * @return a {@code List} containing the specified elements
       * @throws NullPointerException if an element is {@code null} or if the array is {@code null}
       *
       * @since 9
       */
      @SafeVarargs
      @SuppressWarnings("varargs")
      static <E> List<E> of(E... elements) {
          switch (elements.length) { // implicit null check of elements
              case 0:
                  return ImmutableCollections.List0.instance();
              case 1:
                  return new ImmutableCollections.List1<>(elements[0]);
              case 2:
                  return new ImmutableCollections.List2<>(elements[0], elements[1]);
              default:
                  return new ImmutableCollections.ListN<>(elements);
          }
      }
  }
  