ojluni/src/main/java/sun/awt/util/IdentityArrayList.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2007, 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 sun.awt.util;

 import java.util.AbstractList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.ConcurrentModificationException;
 import java.util.List;
 import java.util.RandomAccess;

 /**
  * 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>IdentityArrayList</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 IdentityArrayList,
  * 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>IdentityArrayList</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>IdentityArrayList</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 IdentityArrayList(...));</pre>
  *
  * <p>The iterators returned by this class's <tt>iterator</tt> and
  * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
  * structurally modified at any time after the iterator is created, in any way
  * except through the iterator's own <tt>remove</tt> or <tt>add</tt> 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 <tt>ConcurrentModificationException</tt> 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>
  *
  */

 public class IdentityArrayList<E> extends AbstractList<E>
         implements List<E>, RandomAccess
 {

     /**
      * The array buffer into which the elements of the IdentityArrayList are stored.
      * The capacity of the IdentityArrayList is the length of this array buffer.
      */
     private transient Object[] elementData;

     /**
      * The size of the IdentityArrayList (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
      * @exception IllegalArgumentException if the specified initial capacity
      *            is negative
      */
     public IdentityArrayList(int initialCapacity) {
         super();
         if (initialCapacity < 0)
             throw new IllegalArgumentException("Illegal Capacity: "+
                     initialCapacity);
         this.elementData = new Object[initialCapacity];
     }

     /**
      * Constructs an empty list with an initial capacity of ten.
      */
     public IdentityArrayList() {
         this(10);
     }

     /**
      * 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 IdentityArrayList(Collection<? extends E> c) {
         elementData = c.toArray();
         size = elementData.length;
         // c.toArray might (incorrectly) not return Object[] (see 6260652)
         if (elementData.getClass() != Object[].class)
             elementData = Arrays.copyOf(elementData, size, Object[].class);
     }

     /**
      * Trims the capacity of this <tt>IdentityArrayList</tt> instance to be the
      * list's current size.  An application can use this operation to minimize
      * the storage of an <tt>IdentityArrayList</tt> instance.
      */
     public void trimToSize() {
         modCount++;
         int oldCapacity = elementData.length;
         if (size < oldCapacity) {
             elementData = Arrays.copyOf(elementData, size);
         }
     }

     /**
      * Increases the capacity of this <tt>IdentityArrayList</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) {
         modCount++;
         int oldCapacity = elementData.length;
         if (minCapacity > oldCapacity) {
             Object oldData[] = elementData;
             int newCapacity = (oldCapacity * 3)/2 + 1;
             if (newCapacity < minCapacity)
                 newCapacity = minCapacity;
             // minCapacity is usually close to size, so this is a win:
             elementData = Arrays.copyOf(elementData, newCapacity);
         }
     }

     /**
      * 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 == 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 == get(i))</tt>,
      * or -1 if there is no such index.
      */
     public int indexOf(Object o) {
         for (int i = 0; i < size; i++) {
             if (o == 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 == get(i))</tt>,
      * or -1 if there is no such index.
      */
     public int lastIndexOf(Object o) {
         for (int i = size-1; i >= 0; i--) {
             if (o == elementData[i]) {
                 return i;
             }
         }
         return -1;
     }

     /**
      * 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
      */
     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;
     }

     // 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 {@inheritDoc}
      */
     public E get(int index) {
         rangeCheck(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) {
         rangeCheck(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) {
         ensureCapacity(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) {
         rangeCheckForAdd(index);

         ensureCapacity(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) {
         rangeCheck(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; // 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 == 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) {
         for (int index = 0; index < size; index++) {
             if (o == 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; // 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++;

         // 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;
         ensureCapacity(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) {
         rangeCheckForAdd(index);

         Object[] a = c.toArray();
         int numNew = a.length;
         ensureCapacity(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
      * <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
      * Shifts any succeeding elements to the left (reduces their index).
      * This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
      * (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
      *
      * @param fromIndex index of first element to be removed
      * @param toIndex index after last element to be removed
      * @throws IndexOutOfBoundsException if fromIndex or toIndex out of
      *              range (fromIndex &lt; 0 || fromIndex &gt;= size() || toIndex
      *              &gt; size() || toIndex &lt; fromIndex)
      */
     protected void removeRange(int fromIndex, int toIndex) {
         modCount++;
         int numMoved = size - toIndex;
         System.arraycopy(elementData, toIndex, elementData, fromIndex,
                 numMoved);

         // Let gc do its work
         int newSize = size - (toIndex-fromIndex);
         while (size != newSize)
             elementData[--size] = null;
     }

     /**
      * Checks if the given index is in range.  If not, throws an appropriate
      * runtime exception.  This method does *not* check if the index is
      * negative: It is always used immediately prior to an array access,
      * which throws an ArrayIndexOutOfBoundsException if index is negative.
      */
     private void rangeCheck(int index) {
         if (index >= size)
             throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
     }

     /**
      * A version of rangeCheck used by add and addAll.
      */
     private void rangeCheckForAdd(int index) {
         if (index > size || index < 0)
             throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
     }

     /**
      * 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;
     }
 }
	/*
	* Copyright (c) 2007, 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 sun.awt.util;

	import java.util.AbstractList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.ConcurrentModificationException;
	import java.util.List;
	import java.util.RandomAccess;

	/**
	* 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>IdentityArrayList</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 IdentityArrayList,
	* 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>IdentityArrayList</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>IdentityArrayList</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 IdentityArrayList(...));</pre>
	*
	* <p>The iterators returned by this class's <tt>iterator</tt> and
	* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
	* structurally modified at any time after the iterator is created, in any way
	* except through the iterator's own <tt>remove</tt> or <tt>add</tt> 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 <tt>ConcurrentModificationException</tt> 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>
	*
	*/

	public class IdentityArrayList<E> extends AbstractList<E>
	implements List<E>, RandomAccess
	{

	/**
	* The array buffer into which the elements of the IdentityArrayList are stored.
	* The capacity of the IdentityArrayList is the length of this array buffer.
	*/
	private transient Object[] elementData;

	/**
	* The size of the IdentityArrayList (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
	* @exception IllegalArgumentException if the specified initial capacity
	* is negative
	*/
	public IdentityArrayList(int initialCapacity) {
	super();
	if (initialCapacity < 0)
	throw new IllegalArgumentException("Illegal Capacity: "+
	initialCapacity);
	this.elementData = new Object[initialCapacity];
	}

	/**
	* Constructs an empty list with an initial capacity of ten.
	*/
	public IdentityArrayList() {
	this(10);
	}

	/**
	* 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 IdentityArrayList(Collection<? extends E> c) {
	elementData = c.toArray();
	size = elementData.length;
	// c.toArray might (incorrectly) not return Object[] (see 6260652)
	if (elementData.getClass() != Object[].class)
	elementData = Arrays.copyOf(elementData, size, Object[].class);
	}

	/**
	* Trims the capacity of this <tt>IdentityArrayList</tt> instance to be the
	* list's current size. An application can use this operation to minimize
	* the storage of an <tt>IdentityArrayList</tt> instance.
	*/
	public void trimToSize() {
	modCount++;
	int oldCapacity = elementData.length;
	if (size < oldCapacity) {
	elementData = Arrays.copyOf(elementData, size);
	}
	}

	/**
	* Increases the capacity of this <tt>IdentityArrayList</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) {
	modCount++;
	int oldCapacity = elementData.length;
	if (minCapacity > oldCapacity) {
	Object oldData[] = elementData;
	int newCapacity = (oldCapacity * 3)/2 + 1;
	if (newCapacity < minCapacity)
	newCapacity = minCapacity;
	// minCapacity is usually close to size, so this is a win:
	elementData = Arrays.copyOf(elementData, newCapacity);
	}
	}

	/**
	* 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 ? e==null : o == 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 ? get(i)==null : o == get(i))</tt>,
	* or -1 if there is no such index.
	*/
	public int indexOf(Object o) {
	for (int i = 0; i < size; i++) {
	if (o == 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 ? get(i)==null : o == get(i))</tt>,
	* or -1 if there is no such index.
	*/
	public int lastIndexOf(Object o) {
	for (int i = size-1; i >= 0; i--) {
	if (o == elementData[i]) {
	return i;
	}
	}
	return -1;
	}

	/**
	* 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
	*/
	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;
	}

	// 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 {@inheritDoc}
	*/
	public E get(int index) {
	rangeCheck(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) {
	rangeCheck(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) {
	ensureCapacity(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) {
	rangeCheckForAdd(index);

	ensureCapacity(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) {
	rangeCheck(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; // 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 ? get(i)==null : o == 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) {
	for (int index = 0; index < size; index++) {
	if (o == 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; // 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++;

	// 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;
	ensureCapacity(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) {
	rangeCheckForAdd(index);

	Object[] a = c.toArray();
	int numNew = a.length;
	ensureCapacity(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
	* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive.
	* Shifts any succeeding elements to the left (reduces their index).
	* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements.
	* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.)
	*
	* @param fromIndex index of first element to be removed
	* @param toIndex index after last element to be removed
	* @throws IndexOutOfBoundsException if fromIndex or toIndex out of
	* range (fromIndex < 0 \|\| fromIndex >= size() \|\| toIndex
	* > size() \|\| toIndex < fromIndex)
	*/
	protected void removeRange(int fromIndex, int toIndex) {
	modCount++;
	int numMoved = size - toIndex;
	System.arraycopy(elementData, toIndex, elementData, fromIndex,
	numMoved);

	// Let gc do its work
	int newSize = size - (toIndex-fromIndex);
	while (size != newSize)
	elementData[--size] = null;
	}

	/**
	* Checks if the given index is in range. If not, throws an appropriate
	* runtime exception. This method does not check if the index is
	* negative: It is always used immediately prior to an array access,
	* which throws an ArrayIndexOutOfBoundsException if index is negative.
	*/
	private void rangeCheck(int index) {
	if (index >= size)
	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
	}

	/**
	* A version of rangeCheck used by add and addAll.
	*/
	private void rangeCheckForAdd(int index) {
	if (index > size \|\| index < 0)
	throw new IndexOutOfBoundsException(outOfBoundsMsg(index));
	}

	/**
	* 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;
	}
	}