content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   * 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.Consumer;
  import java.util.function.Predicate;
  import java.util.function.UnaryOperator;
  
  /**
   * Resizable-array implementation of the <tt>List</tt> interface.  Implements
   * all optional list operations, and permits all elements, including
   * <tt>null</tt>.  In addition to implementing the <tt>List</tt> interface,
   * this class provides methods to manipulate the size of the array that is
   * used internally to store the list.  (This class is roughly equivalent to
   * <tt>Vector</tt>, except that it is unsynchronized.)
   *
   * <p>The <tt>size</tt>, <tt>isEmpty</tt>, <tt>get</tt>, <tt>set</tt>,
   * <tt>iterator</tt>, and <tt>listIterator</tt> operations run in constant
   * time.  The <tt>add</tt> operation runs in <i>amortized constant time</i>,
   * that is, adding n elements requires O(n) time.  All of the other operations
   * run in linear time (roughly speaking).  The constant factor is low compared
   * to that for the <tt>LinkedList</tt> implementation.
   *
   * <p>Each <tt>ArrayList</tt> instance has a <i>capacity</i>.  The capacity is
   * the size of the array used to store the elements in the list.  It is always
   * at least as large as the list size.  As elements are added to an ArrayList,
   * its capacity grows automatically.  The details of the growth policy are not
   * specified beyond the fact that adding an element has constant amortized
   * time cost.
   *
   * <p>An application can increase the capacity of an <tt>ArrayList</tt> instance
   * before adding a large number of elements using the <tt>ensureCapacity</tt>
   * operation.  This may reduce the amount of incremental reallocation.
   *
   * <p><strong>Note that this implementation is not synchronized.</strong>
   * If multiple threads access an <tt>ArrayList</tt> instance concurrently,
   * and at least one of the threads modifies the list structurally, it
   * <i>must</i> be synchronized externally.  (A structural modification is
   * any operation that adds or deletes one or more elements, or explicitly
   * resizes the backing array; merely setting the value of an element is not
   * a structural modification.)  This is typically accomplished by
   * synchronizing on some object that naturally encapsulates the list.
   *
   * If no such object exists, the list should be "wrapped" using the
   * {@link Collections#synchronizedList Collections.synchronizedList}
   * method.  This is best done at creation time, to prevent accidental
   * unsynchronized access to the list:<pre>
   *   List list = Collections.synchronizedList(new ArrayList(...));</pre>
   *
   * <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 list 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.
   *
   * <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>This class is a member of the
   * <a href="{@docRoot}/../technotes/guides/collections/index.html">
   * Java Collections Framework</a>.
   *
   * @author  Josh Bloch
   * @author  Neal Gafter
   * @see     Collection
   * @see     List
   * @see     LinkedList
   * @see     Vector
   * @since   1.2
   */
  // Android-changed: Inlined methods; CME in iterators; throw AIOOBE when toIndex < fromIndex.
  /*
   * - AOSP commit 3be987f0f18648b3c532c8b89d09505e18594241
   *   Inline for improved performance:
   *   - checkForComodification
   *   - elementData()
   *   - rangeCheck()
   *   - rangeCheckForAdd()
   * - AOSP commit b10b2a3ab693cfd6156d06ffe4e00ce69b9c9194
   *   Fix ConcurrentModificationException in ArrayList iterators.
   * - AOSP commit a68b1a5ba82ef8cc19aafdce7d9c7f9631943f84
   *   Throw AIOOBE when toIndex < fromIndex.
   */
  public class ArrayList<E> extends AbstractList<E>
          implements List<E>, RandomAccess, Cloneable, java.io.Serializable
  {
      private static final long serialVersionUID = 8683452581122892189L;
  
      /**
       * Default initial capacity.
       */
      private static final int DEFAULT_CAPACITY = 10;
  
      /**
       * Shared empty array instance used for empty instances.
       */
      private static final Object[] EMPTY_ELEMENTDATA = {};
  
      /**
       * Shared empty array instance used for default sized empty instances. We
       * distinguish this from EMPTY_ELEMENTDATA to know how much to inflate when
       * first element is added.
       */
      private static final Object[] DEFAULTCAPACITY_EMPTY_ELEMENTDATA = {};
  
      /**
       * The array buffer into which the elements of the ArrayList are stored.
       * The capacity of the ArrayList is the length of this array buffer. Any
       * empty ArrayList with elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA
       * will be expanded to DEFAULT_CAPACITY when the first element is added.
       */
      // Android-note: Also accessed from java.util.Collections
      transient Object[] elementData; // non-private to simplify nested class access
  
      /**
       * The size of the ArrayList (the number of elements it contains).
       *
       * @serial
       */
      private int size;
  
      /**
       * Constructs an empty list with the specified initial capacity.
       *
       * @param  initialCapacity  the initial capacity of the list
       * @throws IllegalArgumentException if the specified initial capacity
       *         is negative
       */
      public ArrayList(int initialCapacity) {
          if (initialCapacity > 0) {
              this.elementData = new Object[initialCapacity];
          } else if (initialCapacity == 0) {
              this.elementData = EMPTY_ELEMENTDATA;
          } else {
              throw new IllegalArgumentException("Illegal Capacity: "+
                                                 initialCapacity);
          }
      }
  
      /**
       * Constructs an empty list with an initial capacity of ten.
       */
      public ArrayList() {
          this.elementData = DEFAULTCAPACITY_EMPTY_ELEMENTDATA;
      }
  
      /**
       * Constructs a list 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 list
       * @throws NullPointerException if the specified collection is null
       */
      public ArrayList(Collection<? extends E> c) {
          elementData = c.toArray();
          if ((size = elementData.length) != 0) {
              // c.toArray might (incorrectly) not return Object[] (see 6260652)
              if (elementData.getClass() != Object[].class)
                  elementData = Arrays.copyOf(elementData, size, Object[].class);
          } else {
              // replace with empty array.
              this.elementData = EMPTY_ELEMENTDATA;
          }
      }
  
      /**
       * Trims the capacity of this <tt>ArrayList</tt> instance to be the
       * list's current size.  An application can use this operation to minimize
       * the storage of an <tt>ArrayList</tt> instance.
       */
      public void trimToSize() {
          modCount++;
          if (size < elementData.length) {
              elementData = (size == 0)
                ? EMPTY_ELEMENTDATA
                : Arrays.copyOf(elementData, size);
          }
      }
  
      /**
       * Increases the capacity of this <tt>ArrayList</tt> instance, if
       * necessary, to ensure that it can hold at least the number of elements
       * specified by the minimum capacity argument.
       *
       * @param   minCapacity   the desired minimum capacity
       */
      public void ensureCapacity(int minCapacity) {
          int minExpand = (elementData != DEFAULTCAPACITY_EMPTY_ELEMENTDATA)
              // any size if not default element table
              ? 0
              // larger than default for default empty table. It's already
              // supposed to be at default size.
              : DEFAULT_CAPACITY;
  
          if (minCapacity > minExpand) {
              ensureExplicitCapacity(minCapacity);
          }
      }
  
      private void ensureCapacityInternal(int minCapacity) {
          if (elementData == DEFAULTCAPACITY_EMPTY_ELEMENTDATA) {
              minCapacity = Math.max(DEFAULT_CAPACITY, minCapacity);
          }
  
          ensureExplicitCapacity(minCapacity);
      }
  
      private void ensureExplicitCapacity(int minCapacity) {
          modCount++;
  
          // 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;
  
      /**
       * Increases the capacity to ensure that it can hold at least the
       * number of elements specified by the minimum capacity argument.
       *
       * @param minCapacity the desired minimum capacity
       */
      private void grow(int minCapacity) {
          // overflow-conscious code
          int oldCapacity = elementData.length;
          int newCapacity = oldCapacity + (oldCapacity >> 1);
          if (newCapacity - minCapacity < 0)
              newCapacity = minCapacity;
          if (newCapacity - MAX_ARRAY_SIZE > 0)
              newCapacity = hugeCapacity(minCapacity);
          // minCapacity is usually close to size, so this is a win:
          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;
      }
  
      /**
       * Returns the number of elements in this list.
       *
       * @return the number of elements in this list
       */
      public int size() {
          return size;
      }
  
      /**
       * Returns <tt>true</tt> if this list contains no elements.
       *
       * @return <tt>true</tt> if this list contains no elements
       */
      public boolean isEmpty() {
          return size == 0;
      }
  
      /**
       * Returns <tt>true</tt> if this list contains the specified element.
       * More formally, returns <tt>true</tt> if and only if this list contains
       * at least one element <tt>e</tt> such that
       * <tt>(o==null&nbsp;?&nbsp;e==null&nbsp;:&nbsp;o.equals(e))</tt>.
       *
       * @param o element whose presence in this list is to be tested
       * @return <tt>true</tt> if this list contains the specified element
       */
      public boolean contains(Object o) {
          return indexOf(o) >= 0;
      }
  
      /**
       * 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 <tt>i</tt> 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.
       */
      public int indexOf(Object o) {
          if (o == null) {
              for (int i = 0; i < size; i++)
                  if (elementData[i]==null)
                      return i;
          } else {
              for (int i = 0; i < size; i++)
                  if (o.equals(elementData[i]))
                      return i;
          }
          return -1;
      }
  
      /**
       * 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 <tt>i</tt> 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.
       */
      public int lastIndexOf(Object o) {
          if (o == null) {
              for (int i = size-1; i >= 0; i--)
                  if (elementData[i]==null)
                      return i;
          } else {
              for (int i = size-1; i >= 0; i--)
                  if (o.equals(elementData[i]))
                      return i;
          }
          return -1;
      }
  
      /**
       * Returns a shallow copy of this <tt>ArrayList</tt> instance.  (The
       * elements themselves are not copied.)
       *
       * @return a clone of this <tt>ArrayList</tt> instance
       */
      public Object clone() {
          try {
              ArrayList<?> v = (ArrayList<?>) super.clone();
              v.elementData = Arrays.copyOf(elementData, size);
              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 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).  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
       */
      public Object[] toArray() {
          return Arrays.copyOf(elementData, size);
      }
  
      /**
       * 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 collection is set to
       * <tt>null</tt>.  (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.)
       *
       * @param a the array into which the elements of the 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 the 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
       */
      @SuppressWarnings("unchecked")
      public <T> T[] toArray(T[] a) {
          if (a.length < size)
              // Make a new array of a's runtime type, but my contents:
              return (T[]) Arrays.copyOf(elementData, size, a.getClass());
          System.arraycopy(elementData, 0, a, 0, size);
          if (a.length > size)
              a[size] = null;
          return a;
      }
  
      /**
       * 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 {@inheritDoc}
       */
      public E get(int index) {
          if (index >= size)
              throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
  
          return (E) elementData[index];
      }
  
      /**
       * Replaces the element at the specified position in this list 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 IndexOutOfBoundsException {@inheritDoc}
       */
      public E set(int index, E element) {
          if (index >= size)
              throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
  
          E oldValue = (E) elementData[index];
          elementData[index] = element;
          return oldValue;
      }
  
      /**
       * Appends the specified element to the end of this list.
       *
       * @param e element to be appended to this list
       * @return <tt>true</tt> (as specified by {@link Collection#add})
       */
      public boolean add(E e) {
          ensureCapacityInternal(size + 1);  // Increments modCount!!
          elementData[size++] = e;
          return true;
      }
  
      /**
       * Inserts the specified element at the specified position in this
       * list. 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 IndexOutOfBoundsException {@inheritDoc}
       */
      public void add(int index, E element) {
          if (index > size || index < 0)
              throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
  
          ensureCapacityInternal(size + 1);  // Increments modCount!!
          System.arraycopy(elementData, index, elementData, index + 1,
                           size - index);
          elementData[index] = element;
          size++;
      }
  
      /**
       * Removes the element at the specified position in this list.
       * Shifts any subsequent elements to the left (subtracts one from their
       * indices).
       *
       * @param index the index of the element to be removed
       * @return the element that was removed from the list
       * @throws IndexOutOfBoundsException {@inheritDoc}
       */
      public E remove(int index) {
          if (index >= size)
              throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
  
          modCount++;
          E oldValue = (E) elementData[index];
  
          int numMoved = size - index - 1;
          if (numMoved > 0)
              System.arraycopy(elementData, index+1, elementData, index,
                               numMoved);
          elementData[--size] = null; // clear to let GC do its work
  
          return oldValue;
      }
  
      /**
       * Removes the first occurrence of the specified element from this list,
       * if it is present.  If the list does not contain the element, it is
       * unchanged.  More formally, removes the element with the lowest index
       * <tt>i</tt> such that
       * <tt>(o==null&nbsp;?&nbsp;get(i)==null&nbsp;:&nbsp;o.equals(get(i)))</tt>
       * (if such an element exists).  Returns <tt>true</tt> 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 <tt>true</tt> if this list contained the specified element
       */
      public boolean remove(Object o) {
          if (o == null) {
              for (int index = 0; index < size; index++)
                  if (elementData[index] == null) {
                      fastRemove(index);
                      return true;
                  }
          } else {
              for (int index = 0; index < size; index++)
                  if (o.equals(elementData[index])) {
                      fastRemove(index);
                      return true;
                  }
          }
          return false;
      }
  
      /*
       * Private remove method that skips bounds checking and does not
       * return the value removed.
       */
      private void fastRemove(int index) {
          modCount++;
          int numMoved = size - index - 1;
          if (numMoved > 0)
              System.arraycopy(elementData, index+1, elementData, index,
                               numMoved);
          elementData[--size] = null; // clear to let GC do its work
      }
  
      /**
       * Removes all of the elements from this list.  The list will
       * be empty after this call returns.
       */
      public void clear() {
          modCount++;
  
          // clear to let GC do its work
          for (int i = 0; i < size; i++)
              elementData[i] = null;
  
          size = 0;
      }
  
      /**
       * 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.  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 list, and this
       * list is nonempty.)
       *
       * @param c collection containing elements to be added to this list
       * @return <tt>true</tt> if this list changed as a result of the call
       * @throws NullPointerException if the specified collection is null
       */
      public boolean addAll(Collection<? extends E> c) {
          Object[] a = c.toArray();
          int numNew = a.length;
          ensureCapacityInternal(size + numNew);  // Increments modCount
          System.arraycopy(a, 0, elementData, size, numNew);
          size += numNew;
          return numNew != 0;
      }
  
      /**
       * Inserts all of the elements in the specified collection into this
       * list, starting 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 list 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 collection containing elements to be added to this list
       * @return <tt>true</tt> if this list changed as a result of the call
       * @throws IndexOutOfBoundsException {@inheritDoc}
       * @throws NullPointerException if the specified collection is null
       */
      public boolean addAll(int index, Collection<? extends E> c) {
          if (index > size || index < 0)
              throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
  
          Object[] a = c.toArray();
          int numNew = a.length;
          ensureCapacityInternal(size + numNew);  // Increments modCount
  
          int numMoved = size - index;
          if (numMoved > 0)
              System.arraycopy(elementData, index, elementData, index + numNew,
                               numMoved);
  
          System.arraycopy(a, 0, elementData, index, numNew);
          size += numNew;
          return numNew != 0;
      }
  
      /**
       * 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.)
       *
       * @throws IndexOutOfBoundsException if {@code fromIndex} or
       *         {@code toIndex} is out of range
       *         ({@code fromIndex < 0 ||
       *          fromIndex >= size() ||
       *          toIndex > size() ||
       *          toIndex < fromIndex})
       */
      protected void removeRange(int fromIndex, int toIndex) {
          // Android-changed: Throw an IOOBE if toIndex < fromIndex as documented.
          // All the other cases (negative indices, or indices greater than the size
          // will be thrown by System#arrayCopy.
          if (toIndex < fromIndex) {
              throw new IndexOutOfBoundsException("toIndex < fromIndex");
          }
  
          modCount++;
          int numMoved = size - toIndex;
          System.arraycopy(elementData, toIndex, elementData, fromIndex,
                           numMoved);
  
          // clear to let GC do its work
          int newSize = size - (toIndex-fromIndex);
          for (int i = newSize; i < size; i++) {
              elementData[i] = null;
          }
          size = newSize;
      }
  
      /**
       * Constructs an IndexOutOfBoundsException detail message.
       * Of the many possible refactorings of the error handling code,
       * this "outlining" performs best with both server and client VMs.
       */
      private String outOfBoundsMsg(int index) {
          return "Index: "+index+", Size: "+size;
      }
  
      /**
       * Removes from this list all of its elements that are contained in the
       * specified collection.
       *
       * @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 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 Collection#contains(Object)
       */
      public boolean removeAll(Collection<?> c) {
          Objects.requireNonNull(c);
          return batchRemove(c, false);
      }
  
      /**
       * Retains only the elements in this list that are contained in the
       * specified collection.  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 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 Collection#contains(Object)
       */
      public boolean retainAll(Collection<?> c) {
          Objects.requireNonNull(c);
          return batchRemove(c, true);
      }
  
      private boolean batchRemove(Collection<?> c, boolean complement) {
          final Object[] elementData = this.elementData;
          int r = 0, w = 0;
          boolean modified = false;
          try {
              for (; r < size; r++)
                  if (c.contains(elementData[r]) == complement)
                      elementData[w++] = elementData[r];
          } finally {
              // Preserve behavioral compatibility with AbstractCollection,
              // even if c.contains() throws.
              if (r != size) {
                  System.arraycopy(elementData, r,
                                   elementData, w,
                                   size - r);
                  w += size - r;
              }
              if (w != size) {
                  // clear to let GC do its work
                  for (int i = w; i < size; i++)
                      elementData[i] = null;
                  modCount += size - w;
                  size = w;
                  modified = true;
              }
          }
          return modified;
      }
  
      /**
       * Save the state of the <tt>ArrayList</tt> instance to a stream (that
       * is, serialize it).
       *
       * @serialData The length of the array backing the <tt>ArrayList</tt>
       *             instance is emitted (int), followed by all of its elements
       *             (each an <tt>Object</tt>) in the proper order.
       */
      private void writeObject(java.io.ObjectOutputStream s)
          throws java.io.IOException{
          // Write out element count, and any hidden stuff
          int expectedModCount = modCount;
          s.defaultWriteObject();
  
          // Write out size as capacity for behavioural compatibility with clone()
          s.writeInt(size);
  
          // Write out all elements in the proper order.
          for (int i=0; i<size; i++) {
              s.writeObject(elementData[i]);
          }
  
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
      }
  
      /**
       * Reconstitute the <tt>ArrayList</tt> instance from a stream (that is,
       * deserialize it).
       */
      private void readObject(java.io.ObjectInputStream s)
          throws java.io.IOException, ClassNotFoundException {
          elementData = EMPTY_ELEMENTDATA;
  
          // Read in size, and any hidden stuff
          s.defaultReadObject();
  
          // Read in capacity
          s.readInt(); // ignored
  
          if (size > 0) {
              // be like clone(), allocate array based upon size not capacity
              ensureCapacityInternal(size);
  
              Object[] a = elementData;
              // Read in all elements in the proper order.
              for (int i=0; i<size; i++) {
                  a[i] = s.readObject();
              }
          }
      }
  
      /**
       * 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 ListIterator<E> listIterator(int index) {
          if (index < 0 || index > size)
              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 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 Iterator<E> iterator() {
          return new Itr();
      }
  
      /**
       * An optimized version of AbstractList.Itr
       */
      private class Itr implements Iterator<E> {
          // Android-changed: Add "limit" field to detect end of iteration.
          // 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 = ArrayList.this.size;
  
          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() {
              return cursor < limit;
          }
  
          @SuppressWarnings("unchecked")
          public E next() {
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
              int i = cursor;
              if (i >= limit)
                  throw new NoSuchElementException();
              Object[] elementData = ArrayList.this.elementData;
              if (i >= elementData.length)
                  throw new ConcurrentModificationException();
              cursor = i + 1;
              return (E) elementData[lastRet = i];
          }
  
          public void remove() {
              if (lastRet < 0)
                  throw new IllegalStateException();
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
  
              try {
                  ArrayList.this.remove(lastRet);
                  cursor = lastRet;
                  lastRet = -1;
                  expectedModCount = modCount;
                  limit--;
              } catch (IndexOutOfBoundsException ex) {
                  throw new ConcurrentModificationException();
              }
          }
  
          @Override
          @SuppressWarnings("unchecked")
          public void forEachRemaining(Consumer<? super E> consumer) {
              Objects.requireNonNull(consumer);
              final int size = ArrayList.this.size;
              int i = cursor;
              if (i >= size) {
                  return;
              }
              final Object[] elementData = ArrayList.this.elementData;
              if (i >= elementData.length) {
                  throw new ConcurrentModificationException();
              }
              while (i != size && modCount == expectedModCount) {
                  consumer.accept((E) elementData[i++]);
              }
              // update once at end of iteration to reduce heap write traffic
              cursor = i;
              lastRet = i - 1;
  
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
          }
      }
  
      /**
       * An optimized version of AbstractList.ListItr
       */
      private 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;
          }
  
          @SuppressWarnings("unchecked")
          public E previous() {
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
              int i = cursor - 1;
              if (i < 0)
                  throw new NoSuchElementException();
              Object[] elementData = ArrayList.this.elementData;
              if (i >= elementData.length)
                  throw new ConcurrentModificationException();
              cursor = i;
              return (E) elementData[lastRet = i];
          }
  
          public void set(E e) {
              if (lastRet < 0)
                  throw new IllegalStateException();
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
  
              try {
                  ArrayList.this.set(lastRet, e);
              } catch (IndexOutOfBoundsException ex) {
                  throw new ConcurrentModificationException();
              }
          }
  
          public void add(E e) {
              if (modCount != expectedModCount)
                  throw new ConcurrentModificationException();
  
              try {
                  int i = cursor;
                  ArrayList.this.add(i, e);
                  cursor = i + 1;
                  lastRet = -1;
                  expectedModCount = modCount;
                  limit++;
              } catch (IndexOutOfBoundsException ex) {
                  throw new ConcurrentModificationException();
              }
          }
      }
  
      /**
       * 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.
       *
       * <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>
       *      list.subList(from, to).clear();
       * </pre>
       * Similar idioms may be constructed for {@link #indexOf(Object)} and
       * {@link #lastIndexOf(Object)}, and all of the algorithms in the
       * {@link 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.)
       *
       * @throws IndexOutOfBoundsException {@inheritDoc}
       * @throws IllegalArgumentException {@inheritDoc}
       */
      public List<E> subList(int fromIndex, int toIndex) {
          subListRangeCheck(fromIndex, toIndex, size);
          return new SubList(this, 0, fromIndex, toIndex);
      }
  
      static void subListRangeCheck(int fromIndex, int toIndex, int size) {
          if (fromIndex < 0)
              throw new IndexOutOfBoundsException("fromIndex = " + fromIndex);
          if (toIndex > size)
              throw new IndexOutOfBoundsException("toIndex = " + toIndex);
          if (fromIndex > toIndex)
              throw new IllegalArgumentException("fromIndex(" + fromIndex +
                                                 ") > toIndex(" + toIndex + ")");
      }
  
      private class SubList extends AbstractList<E> implements RandomAccess {
          private final AbstractList<E> parent;
          private final int parentOffset;
          private final int offset;
          int size;
  
          SubList(AbstractList<E> parent,
                  int offset, int fromIndex, int toIndex) {
              this.parent = parent;
              this.parentOffset = fromIndex;
              this.offset = offset + fromIndex;
              this.size = toIndex - fromIndex;
              this.modCount = ArrayList.this.modCount;
          }
  
          public E set(int index, E e) {
              if (index < 0 || index >= this.size)
                  throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              E oldValue = (E) ArrayList.this.elementData[offset + index];
              ArrayList.this.elementData[offset + index] = e;
              return oldValue;
          }
  
          public E get(int index) {
              if (index < 0 || index >= this.size)
                throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              return (E) ArrayList.this.elementData[offset + index];
          }
  
          public int size() {
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              return this.size;
          }
  
          public void add(int index, E e) {
              if (index < 0 || index > this.size)
                  throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              parent.add(parentOffset + index, e);
              this.modCount = parent.modCount;
              this.size++;
          }
  
          public E remove(int index) {
              if (index < 0 || index >= this.size)
                  throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              E result = parent.remove(parentOffset + index);
              this.modCount = parent.modCount;
              this.size--;
              return result;
          }
  
          protected void removeRange(int fromIndex, int toIndex) {
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              parent.removeRange(parentOffset + fromIndex,
                                 parentOffset + toIndex);
              this.modCount = parent.modCount;
              this.size -= toIndex - fromIndex;
          }
  
          public boolean addAll(Collection<? extends E> c) {
              return addAll(this.size, c);
          }
  
          public boolean addAll(int index, Collection<? extends E> c) {
              if (index < 0 || index > this.size)
                  throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              int cSize = c.size();
              if (cSize==0)
                  return false;
  
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              parent.addAll(parentOffset + index, c);
              this.modCount = parent.modCount;
              this.size += cSize;
              return true;
          }
  
          public Iterator<E> iterator() {
              return listIterator();
          }
  
          public ListIterator<E> listIterator(final int index) {
              if (ArrayList.this.modCount != this.modCount)
                  throw new ConcurrentModificationException();
              if (index < 0 || index > this.size)
                  throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
              final int offset = this.offset;
  
              return new ListIterator<E>() {
                  int cursor = index;
                  int lastRet = -1;
                  int expectedModCount = ArrayList.this.modCount;
  
                  public boolean hasNext() {
                      return cursor != SubList.this.size;
                  }
  
                  @SuppressWarnings("unchecked")
                  public E next() {
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
                      int i = cursor;
                      if (i >= SubList.this.size)
                          throw new NoSuchElementException();
                      Object[] elementData = ArrayList.this.elementData;
                      if (offset + i >= elementData.length)
                          throw new ConcurrentModificationException();
                      cursor = i + 1;
                      return (E) elementData[offset + (lastRet = i)];
                  }
  
                  public boolean hasPrevious() {
                      return cursor != 0;
                  }
  
                  @SuppressWarnings("unchecked")
                  public E previous() {
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
                      int i = cursor - 1;
                      if (i < 0)
                          throw new NoSuchElementException();
                      Object[] elementData = ArrayList.this.elementData;
                      if (offset + i >= elementData.length)
                          throw new ConcurrentModificationException();
                      cursor = i;
                      return (E) elementData[offset + (lastRet = i)];
                  }
  
                  @SuppressWarnings("unchecked")
                  public void forEachRemaining(Consumer<? super E> consumer) {
                      Objects.requireNonNull(consumer);
                      final int size = SubList.this.size;
                      int i = cursor;
                      if (i >= size) {
                          return;
                      }
                      final Object[] elementData = ArrayList.this.elementData;
                      if (offset + i >= elementData.length) {
                          throw new ConcurrentModificationException();
                      }
                      while (i != size && modCount == expectedModCount) {
                          consumer.accept((E) elementData[offset + (i++)]);
                      }
                      // update once at end of iteration to reduce heap write traffic
                      lastRet = cursor = i;
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
                  }
  
                  public int nextIndex() {
                      return cursor;
                  }
  
                  public int previousIndex() {
                      return cursor - 1;
                  }
  
                  public void remove() {
                      if (lastRet < 0)
                          throw new IllegalStateException();
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
  
                      try {
                          SubList.this.remove(lastRet);
                          cursor = lastRet;
                          lastRet = -1;
                          expectedModCount = ArrayList.this.modCount;
                      } catch (IndexOutOfBoundsException ex) {
                          throw new ConcurrentModificationException();
                      }
                  }
  
                  public void set(E e) {
                      if (lastRet < 0)
                          throw new IllegalStateException();
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
  
                      try {
                          ArrayList.this.set(offset + lastRet, e);
                      } catch (IndexOutOfBoundsException ex) {
                          throw new ConcurrentModificationException();
                      }
                  }
  
                  public void add(E e) {
                      if (expectedModCount != ArrayList.this.modCount)
                          throw new ConcurrentModificationException();
  
                      try {
                          int i = cursor;
                          SubList.this.add(i, e);
                          cursor = i + 1;
                          lastRet = -1;
                          expectedModCount = ArrayList.this.modCount;
                      } catch (IndexOutOfBoundsException ex) {
                          throw new ConcurrentModificationException();
                      }
                  }
              };
          }
  
          public List<E> subList(int fromIndex, int toIndex) {
              subListRangeCheck(fromIndex, toIndex, size);
              return new SubList(this, offset, fromIndex, toIndex);
          }
  
          private String outOfBoundsMsg(int index) {
              return "Index: "+index+", Size: "+this.size;
          }
  
          public Spliterator<E> spliterator() {
              if (modCount != ArrayList.this.modCount)
                  throw new ConcurrentModificationException();
              return new ArrayListSpliterator<E>(ArrayList.this, offset,
                                                 offset + this.size, this.modCount);
          }
      }
  
      @Override
      public void forEach(Consumer<? super E> action) {
          Objects.requireNonNull(action);
          final int expectedModCount = modCount;
          @SuppressWarnings("unchecked")
          final E[] elementData = (E[]) this.elementData;
          final int size = this.size;
          for (int i=0; modCount == expectedModCount && i < size; i++) {
              action.accept(elementData[i]);
          }
          // Android-note:
          // Iterator will not throw a CME if we add something while iterating over the *last* element
          // forEach will throw a CME in this case.
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
      }
  
      /**
       * 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 ArrayListSpliterator<>(this, 0, -1, 0);
      }
  
      /** Index-based split-by-two, lazily initialized Spliterator */
      static final class ArrayListSpliterator<E> implements Spliterator<E> {
  
          /*
           * If ArrayLists were immutable, or structurally immutable (no
           * adds, removes, etc), we could implement their spliterators
           * with Arrays.spliterator. Instead we detect as much
           * interference during traversal as practical without
           * sacrificing much performance. We rely primarily on
           * modCounts. These are not guaranteed to detect concurrency
           * violations, and are sometimes overly conservative about
           * within-thread interference, but detect enough problems to
           * be worthwhile in practice. To carry this out, we (1) lazily
           * initialize fence and expectedModCount until the latest
           * point that we need to commit to the state we are checking
           * against; thus improving precision.  (This doesn't apply to
           * SubLists, that create spliterators with current non-lazy
           * values).  (2) We perform only a single
           * ConcurrentModificationException check at the end of forEach
           * (the most performance-sensitive method). When using forEach
           * (as opposed to iterators), we can normally only detect
           * interference after actions, not before. Further
           * CME-triggering checks apply to all other possible
           * violations of assumptions for example null or too-small
           * elementData array given its size(), that could only have
           * occurred due to interference.  This allows the inner loop
           * of forEach to run without any further checks, and
           * simplifies lambda-resolution. While this does entail a
           * number of checks, note that in the common case of
           * list.stream().forEach(a), no checks or other computation
           * occur anywhere other than inside forEach itself.  The other
           * less-often-used methods cannot take advantage of most of
           * these streamlinings.
           */
  
          private final ArrayList<E> list;
          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 */
          ArrayListSpliterator(ArrayList<E> list, int origin, int fence,
                               int expectedModCount) {
              this.list = list; // OK if null unless traversed
              this.index = origin;
              this.fence = fence;
              this.expectedModCount = expectedModCount;
          }
  
          private int getFence() { // initialize fence to size on first use
              int hi; // (a specialized variant appears in method forEach)
              ArrayList<E> lst;
              if ((hi = fence) < 0) {
                  if ((lst = list) == null)
                      hi = fence = 0;
                  else {
                      expectedModCount = lst.modCount;
                      hi = fence = lst.size;
                  }
              }
              return hi;
          }
  
          public ArrayListSpliterator<E> trySplit() {
              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
              return (lo >= mid) ? null : // divide range in half unless too small
                  new ArrayListSpliterator<E>(list, lo, index = mid,
                                              expectedModCount);
          }
  
          public boolean tryAdvance(Consumer<? super E> action) {
              if (action == null)
                  throw new NullPointerException();
              int hi = getFence(), i = index;
              if (i < hi) {
                  index = i + 1;
                  @SuppressWarnings("unchecked") E e = (E)list.elementData[i];
                  action.accept(e);
                  if (list.modCount != expectedModCount)
                      throw new ConcurrentModificationException();
                  return true;
              }
              return false;
          }
  
          public void forEachRemaining(Consumer<? super E> action) {
              int i, hi, mc; // hoist accesses and checks from loop
              ArrayList<E> lst; Object[] a;
              if (action == null)
                  throw new NullPointerException();
              if ((lst = list) != null && (a = lst.elementData) != null) {
                  if ((hi = fence) < 0) {
                      mc = lst.modCount;
                      hi = lst.size;
                  }
                  else
                      mc = expectedModCount;
                  if ((i = index) >= 0 && (index = hi) <= a.length) {
                      for (; i < hi; ++i) {
                          @SuppressWarnings("unchecked") E e = (E) a[i];
                          action.accept(e);
                      }
                      if (lst.modCount == mc)
                          return;
                  }
              }
              throw new ConcurrentModificationException();
          }
  
          public long estimateSize() {
              return (long) (getFence() - index);
          }
  
          public int characteristics() {
              return Spliterator.ORDERED | Spliterator.SIZED | Spliterator.SUBSIZED;
          }
      }
  
      @Override
      public 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 BitSet removeSet = new BitSet(size);
          final int expectedModCount = modCount;
          final int size = this.size;
          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
              }
              this.size = newSize;
              if (modCount != expectedModCount) {
                  throw new ConcurrentModificationException();
              }
              modCount++;
          }
  
          return anyToRemove;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public void replaceAll(UnaryOperator<E> operator) {
          Objects.requireNonNull(operator);
          final int expectedModCount = modCount;
          final int size = this.size;
          for (int i=0; modCount == expectedModCount && i < size; i++) {
              elementData[i] = operator.apply((E) elementData[i]);
          }
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
          modCount++;
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public void sort(Comparator<? super E> c) {
          final int expectedModCount = modCount;
          Arrays.sort((E[]) elementData, 0, size, c);
          if (modCount != expectedModCount) {
              throw new ConcurrentModificationException();
          }
          modCount++;
      }
  }
  