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/* |
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* %W% %E% |
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* |
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* Copyright 2003 Sun Microsystems, Inc. All rights reserved. |
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* Copyright 2005 Sun Microsystems, Inc. All rights reserved. |
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* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. |
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*/ |
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|
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* the <tt>LinkedList</tt> class provides uniformly named methods to |
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* <tt>get</tt>, <tt>remove</tt> and <tt>insert</tt> an element at the |
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* beginning and end of the list. These operations allow linked lists to be |
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* used as a stack, queue, or double-ended queue (deque).<p> |
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* used as a stack, {@linkplain Queue queue}, or {@linkplain Deque |
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* double-ended queue}. <p> |
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* |
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* The class implements the <tt>Queue</tt> interface, providing |
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* The class implements the <tt>Deque</tt> interface, providing |
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* first-in-first-out queue operations for <tt>add</tt>, |
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* <tt>poll</tt>, etc. Other stack and deque operations could be |
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* easily recast in terms of the standard list operations. They're |
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* included here primarily for convenience, though they may run |
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* slightly faster than the equivalent List operations.<p> |
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* <tt>poll</tt>, along with other stack and deque operations.<p> |
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* |
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* All of the operations perform as could be expected for a doubly-linked |
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* list. Operations that index into the list will traverse the list from |
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* Collections.synchronizedList method. This is best done at creation time, |
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* to prevent accidental unsynchronized access to the list: <pre> |
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* List list = Collections.synchronizedList(new LinkedList(...)); |
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* </pre><p> |
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* </pre> |
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* |
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* The iterators returned by the this class's <tt>iterator</tt> and |
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* <p>The iterators returned by this class's <tt>iterator</tt> and |
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* <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is |
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* structurally modified at any time after the iterator is created, in any way |
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* except through the Iterator's own <tt>remove</tt> or <tt>add</tt> methods, |
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* the iterator will throw a <tt>ConcurrentModificationException</tt>. Thus, |
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* in the face of concurrent modification, the iterator fails quickly and |
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* cleanly, rather than risking arbitrary, non-deterministic behavior at an |
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* undetermined time in the future. |
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* structurally modified at any time after the iterator is created, in |
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* any way except through the Iterator's own <tt>remove</tt> or |
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* <tt>add</tt> methods, the iterator will throw a {@link |
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* ConcurrentModificationException}. Thus, in the face of concurrent |
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* modification, the iterator fails quickly and cleanly, rather than |
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* risking arbitrary, non-deterministic behavior at an undetermined |
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* time in the future. |
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* |
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* <p>Note that the fail-fast behavior of an iterator cannot be guaranteed |
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* as it is, generally speaking, impossible to make any hard guarantees in the |
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* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
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* Therefore, it would be wrong to write a program that depended on this |
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* exception for its correctness: <i>the fail-fast behavior of iterators |
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* should be used only to detect bugs.</i><p> |
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* should be used only to detect bugs.</i> |
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* |
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* This class is a member of the |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @author Josh Bloch |
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* @version %I%, %G% |
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* @see List |
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* @see ArrayList |
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* @see Vector |
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* @see Collections#synchronizedList(List) |
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* @see List |
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* @see ArrayList |
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* @see Vector |
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* @see Collections#synchronizedList(List) |
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* @since 1.2 |
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* @param <E> the type of elements held in this collection |
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*/ |
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|
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public class LinkedList<E> |
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extends AbstractSequentialList<E> |
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implements List<E>, Queue<E>, Cloneable, java.io.Serializable |
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implements List<E>, Deque<E>, Cloneable, java.io.Serializable |
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{ |
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private transient Entry<E> header = new Entry<E>(null, null, null); |
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private transient int size = 0; |
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* collection, in the order they are returned by the collection's |
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* iterator. |
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* |
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* @param c the collection whose elements are to be placed into this list. |
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* @throws NullPointerException if the specified collection is null. |
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* @param c the collection whose elements are to be placed into this list |
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* @throws NullPointerException if the specified collection is null |
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*/ |
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public LinkedList(Collection<? extends E> c) { |
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this(); |
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addAll(c); |
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} |
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public LinkedList(Collection<? extends E> c) { |
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this(); |
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addAll(c); |
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} |
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|
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/** |
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* Returns the first element in this list. |
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* |
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* @return the first element in this list. |
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* @throws NoSuchElementException if this list is empty. |
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* @return the first element in this list |
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* @throws NoSuchElementException if this list is empty |
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*/ |
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public E getFirst() { |
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if (size==0) |
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throw new NoSuchElementException(); |
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if (size==0) |
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throw new NoSuchElementException(); |
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|
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return header.next.element; |
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return header.next.element; |
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} |
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|
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/** |
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* Returns the last element in this list. |
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* |
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* @return the last element in this list. |
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* @throws NoSuchElementException if this list is empty. |
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* @return the last element in this list |
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* @throws NoSuchElementException if this list is empty |
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*/ |
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public E getLast() { |
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if (size==0) |
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throw new NoSuchElementException(); |
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if (size==0) |
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throw new NoSuchElementException(); |
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|
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return header.previous.element; |
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return header.previous.element; |
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} |
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|
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/** |
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* Removes and returns the first element from this list. |
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* |
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* @return the first element from this list. |
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* @throws NoSuchElementException if this list is empty. |
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* @return the first element from this list |
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* @throws NoSuchElementException if this list is empty |
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*/ |
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public E removeFirst() { |
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E first = header.next.element; |
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remove(header.next); |
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return first; |
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return remove(header.next); |
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} |
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|
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/** |
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* Removes and returns the last element from this list. |
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* |
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* @return the last element from this list. |
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* @throws NoSuchElementException if this list is empty. |
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* @return the last element from this list |
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* @throws NoSuchElementException if this list is empty |
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*/ |
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public E removeLast() { |
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E last = header.previous.element; |
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remove(header.previous); |
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return last; |
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> |
return remove(header.previous); |
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} |
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|
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/** |
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* Inserts the given element at the beginning of this list. |
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* |
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* @param o the element to be inserted at the beginning of this list. |
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* @param e the element to be inserted at the beginning of this list |
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*/ |
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public void addFirst(E o) { |
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addBefore(o, header.next); |
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public void addFirst(E e) { |
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addBefore(e, header.next); |
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} |
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|
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/** |
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* Appends the given element to the end of this list. (Identical in |
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* function to the <tt>add</tt> method; included only for consistency.) |
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* |
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* @param o the element to be inserted at the end of this list. |
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* @param e the element to be inserted at the end of this list |
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*/ |
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public void addLast(E o) { |
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addBefore(o, header); |
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public void addLast(E e) { |
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addBefore(e, header); |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this list contains the specified element. |
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* More formally, returns <tt>true</tt> if and only if this list contains |
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* at least one element <tt>e</tt> such that <tt>(o==null ? e==null |
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* : o.equals(e))</tt>. |
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* at least one element <tt>e</tt> such that |
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* <tt>(o==null ? e==null : o.equals(e))</tt>. |
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* |
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* @param o element whose presence in this list is to be tested. |
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* @return <tt>true</tt> if this list contains the specified element. |
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> |
* @param o element whose presence in this list is to be tested |
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> |
* @return <tt>true</tt> if this list contains the specified element |
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*/ |
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public boolean contains(Object o) { |
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return indexOf(o) != -1; |
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/** |
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* Returns the number of elements in this list. |
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* |
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* @return the number of elements in this list. |
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* @return the number of elements in this list |
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*/ |
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public int size() { |
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return size; |
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> |
return size; |
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} |
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|
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/** |
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* Appends the specified element to the end of this list. |
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* |
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< |
* @param o element to be appended to this list. |
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< |
* @return <tt>true</tt> (as per the general contract of |
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< |
* <tt>Collection.add</tt>). |
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* @param e element to be appended to this list |
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> |
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
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*/ |
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public boolean add(E o) { |
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addBefore(o, header); |
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> |
public boolean add(E e) { |
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addBefore(e, header); |
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return true; |
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} |
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|
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/** |
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< |
* Removes the first occurrence of the specified element in this list. If |
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< |
* the list does not contain the element, it is unchanged. More formally, |
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< |
* removes the element with the lowest index <tt>i</tt> such that |
| 202 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> (if such an |
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< |
* element exists). |
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> |
* Removes the first occurrence of the specified element from this list, |
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> |
* if it is present. If this list does not contain the element, it is |
| 201 |
> |
* unchanged. More formally, removes the element with the lowest index |
| 202 |
> |
* <tt>i</tt> such that |
| 203 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
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> |
* (if such an element exists). Returns <tt>true</tt> if this list |
| 205 |
> |
* contained the specified element (or equivalently, if this list |
| 206 |
> |
* changed as a result of the call). |
| 207 |
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* |
| 208 |
< |
* @param o element to be removed from this list, if present. |
| 209 |
< |
* @return <tt>true</tt> if the list contained the specified element. |
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> |
* @param o element to be removed from this list, if present |
| 209 |
> |
* @return <tt>true</tt> if this list contained the specified element |
| 210 |
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*/ |
| 211 |
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public boolean remove(Object o) { |
| 212 |
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if (o==null) { |
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* progress. (This implies that the behavior of this call is undefined if |
| 236 |
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* the specified Collection is this list, and this list is nonempty.) |
| 237 |
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* |
| 238 |
< |
* @param c the elements to be inserted into this list. |
| 239 |
< |
* @return <tt>true</tt> if this list changed as a result of the call. |
| 240 |
< |
* @throws NullPointerException if the specified collection is null. |
| 238 |
> |
* @param c collection containing elements to be added to this list |
| 239 |
> |
* @return <tt>true</tt> if this list changed as a result of the call |
| 240 |
> |
* @throws NullPointerException if the specified collection is null |
| 241 |
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*/ |
| 242 |
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public boolean addAll(Collection<? extends E> c) { |
| 243 |
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return addAll(size, c); |
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* in the list in the order that they are returned by the |
| 252 |
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* specified collection's iterator. |
| 253 |
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* |
| 254 |
< |
* @param index index at which to insert first element |
| 255 |
< |
* from the specified collection. |
| 256 |
< |
* @param c elements to be inserted into this list. |
| 257 |
< |
* @return <tt>true</tt> if this list changed as a result of the call. |
| 258 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
| 259 |
< |
* range (<tt>index < 0 || index > size()</tt>). |
| 263 |
< |
* @throws NullPointerException if the specified collection is null. |
| 254 |
> |
* @param index index at which to insert the first element |
| 255 |
> |
* from the specified collection |
| 256 |
> |
* @param c collection containing elements to be added to this list |
| 257 |
> |
* @return <tt>true</tt> if this list changed as a result of the call |
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> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 259 |
> |
* @throws NullPointerException if the specified collection is null |
| 260 |
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*/ |
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public boolean addAll(int index, Collection<? extends E> c) { |
| 262 |
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if (index < 0 || index > size) |
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int numNew = a.length; |
| 267 |
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if (numNew==0) |
| 268 |
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return false; |
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< |
modCount++; |
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> |
modCount++; |
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|
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Entry<E> successor = (index==size ? header : entry(index)); |
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Entry<E> predecessor = successor.previous; |
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< |
for (int i=0; i<numNew; i++) { |
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> |
for (int i=0; i<numNew; i++) { |
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Entry<E> e = new Entry<E>((E)a[i], successor, predecessor); |
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predecessor.next = e; |
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predecessor = e; |
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* Removes all of the elements from this list. |
| 286 |
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*/ |
| 287 |
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public void clear() { |
| 288 |
< |
modCount++; |
| 288 |
> |
Entry<E> e = header.next; |
| 289 |
> |
while (e != header) { |
| 290 |
> |
Entry<E> next = e.next; |
| 291 |
> |
e.next = e.previous = null; |
| 292 |
> |
e.element = null; |
| 293 |
> |
e = next; |
| 294 |
> |
} |
| 295 |
|
header.next = header.previous = header; |
| 296 |
|
size = 0; |
| 297 |
+ |
modCount++; |
| 298 |
|
} |
| 299 |
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|
| 300 |
|
|
| 303 |
|
/** |
| 304 |
|
* Returns the element at the specified position in this list. |
| 305 |
|
* |
| 306 |
< |
* @param index index of element to return. |
| 307 |
< |
* @return the element at the specified position in this list. |
| 308 |
< |
* |
| 306 |
< |
* @throws IndexOutOfBoundsException if the specified index is is out of |
| 307 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
| 306 |
> |
* @param index index of the element to return |
| 307 |
> |
* @return the element at the specified position in this list |
| 308 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 309 |
|
*/ |
| 310 |
|
public E get(int index) { |
| 311 |
|
return entry(index).element; |
| 315 |
|
* Replaces the element at the specified position in this list with the |
| 316 |
|
* specified element. |
| 317 |
|
* |
| 318 |
< |
* @param index index of element to replace. |
| 319 |
< |
* @param element element to be stored at the specified position. |
| 320 |
< |
* @return the element previously at the specified position. |
| 321 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
| 321 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
| 318 |
> |
* @param index index of the element to replace |
| 319 |
> |
* @param element element to be stored at the specified position |
| 320 |
> |
* @return the element previously at the specified position |
| 321 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 322 |
|
*/ |
| 323 |
|
public E set(int index, E element) { |
| 324 |
|
Entry<E> e = entry(index); |
| 332 |
|
* Shifts the element currently at that position (if any) and any |
| 333 |
|
* subsequent elements to the right (adds one to their indices). |
| 334 |
|
* |
| 335 |
< |
* @param index index at which the specified element is to be inserted. |
| 336 |
< |
* @param element element to be inserted. |
| 337 |
< |
* |
| 338 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
| 339 |
< |
* range (<tt>index < 0 || index > size()</tt>). |
| 335 |
> |
* @param index index at which the specified element is to be inserted |
| 336 |
> |
* @param element element to be inserted |
| 337 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 338 |
|
*/ |
| 339 |
|
public void add(int index, E element) { |
| 340 |
|
addBefore(element, (index==size ? header : entry(index))); |
| 345 |
|
* subsequent elements to the left (subtracts one from their indices). |
| 346 |
|
* Returns the element that was removed from the list. |
| 347 |
|
* |
| 348 |
< |
* @param index the index of the element to removed. |
| 349 |
< |
* @return the element previously at the specified position. |
| 350 |
< |
* |
| 353 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
| 354 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
| 348 |
> |
* @param index the index of the element to be removed |
| 349 |
> |
* @return the element previously at the specified position |
| 350 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 351 |
|
*/ |
| 352 |
|
public E remove(int index) { |
| 353 |
< |
Entry<E> e = entry(index); |
| 358 |
< |
remove(e); |
| 359 |
< |
return e.element; |
| 353 |
> |
return remove(entry(index)); |
| 354 |
|
} |
| 355 |
|
|
| 356 |
|
/** |
| 357 |
< |
* Return the indexed entry. |
| 357 |
> |
* Returns the indexed entry. |
| 358 |
|
*/ |
| 359 |
|
private Entry<E> entry(int index) { |
| 360 |
|
if (index < 0 || index >= size) |
| 375 |
|
// Search Operations |
| 376 |
|
|
| 377 |
|
/** |
| 378 |
< |
* Returns the index in this list of the first occurrence of the |
| 379 |
< |
* specified element, or -1 if the List does not contain this |
| 380 |
< |
* element. More formally, returns the lowest index i such that |
| 381 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if |
| 382 |
< |
* there is no such index. |
| 383 |
< |
* |
| 384 |
< |
* @param o element to search for. |
| 385 |
< |
* @return the index in this list of the first occurrence of the |
| 386 |
< |
* specified element, or -1 if the list does not contain this |
| 393 |
< |
* element. |
| 378 |
> |
* Returns the index of the first occurrence of the specified element |
| 379 |
> |
* in this list, or -1 if this list does not contain the element. |
| 380 |
> |
* More formally, returns the lowest index <tt>i</tt> such that |
| 381 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
| 382 |
> |
* or -1 if there is no such index. |
| 383 |
> |
* |
| 384 |
> |
* @param o element to search for |
| 385 |
> |
* @return the index of the first occurrence of the specified element in |
| 386 |
> |
* this list, or -1 if this list does not contain the element |
| 387 |
|
*/ |
| 388 |
|
public int indexOf(Object o) { |
| 389 |
|
int index = 0; |
| 404 |
|
} |
| 405 |
|
|
| 406 |
|
/** |
| 407 |
< |
* Returns the index in this list of the last occurrence of the |
| 408 |
< |
* specified element, or -1 if the list does not contain this |
| 409 |
< |
* element. More formally, returns the highest index i such that |
| 410 |
< |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, or -1 if |
| 411 |
< |
* there is no such index. |
| 412 |
< |
* |
| 413 |
< |
* @param o element to search for. |
| 414 |
< |
* @return the index in this list of the last occurrence of the |
| 415 |
< |
* specified element, or -1 if the list does not contain this |
| 423 |
< |
* element. |
| 407 |
> |
* Returns the index of the last occurrence of the specified element |
| 408 |
> |
* in this list, or -1 if this list does not contain the element. |
| 409 |
> |
* More formally, returns the highest index <tt>i</tt> such that |
| 410 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt>, |
| 411 |
> |
* or -1 if there is no such index. |
| 412 |
> |
* |
| 413 |
> |
* @param o element to search for |
| 414 |
> |
* @return the index of the last occurrence of the specified element in |
| 415 |
> |
* this list, or -1 if this list does not contain the element |
| 416 |
|
*/ |
| 417 |
|
public int lastIndexOf(Object o) { |
| 418 |
|
int index = size; |
| 436 |
|
|
| 437 |
|
/** |
| 438 |
|
* Retrieves, but does not remove, the head (first element) of this list. |
| 439 |
< |
* @return the head of this queue, or <tt>null</tt> if this queue is empty. |
| 439 |
> |
* @return the head of this list, or <tt>null</tt> if this list is empty |
| 440 |
|
* @since 1.5 |
| 441 |
|
*/ |
| 442 |
|
public E peek() { |
| 447 |
|
|
| 448 |
|
/** |
| 449 |
|
* Retrieves, but does not remove, the head (first element) of this list. |
| 450 |
< |
* @return the head of this queue. |
| 451 |
< |
* @throws NoSuchElementException if this queue is empty. |
| 450 |
> |
* @return the head of this list |
| 451 |
> |
* @throws NoSuchElementException if this list is empty |
| 452 |
|
* @since 1.5 |
| 453 |
|
*/ |
| 454 |
|
public E element() { |
| 456 |
|
} |
| 457 |
|
|
| 458 |
|
/** |
| 459 |
< |
* Retrieves and removes the head (first element) of this list. |
| 460 |
< |
* @return the head of this queue, or <tt>null</tt> if this queue is empty. |
| 459 |
> |
* Retrieves and removes the head (first element) of this list |
| 460 |
> |
* @return the head of this list, or <tt>null</tt> if this list is empty |
| 461 |
|
* @since 1.5 |
| 462 |
|
*/ |
| 463 |
|
public E poll() { |
| 468 |
|
|
| 469 |
|
/** |
| 470 |
|
* Retrieves and removes the head (first element) of this list. |
| 471 |
< |
* @return the head of this queue. |
| 472 |
< |
* @throws NoSuchElementException if this queue is empty. |
| 471 |
> |
* |
| 472 |
> |
* @return the head of this list |
| 473 |
> |
* @throws NoSuchElementException if this list is empty |
| 474 |
|
* @since 1.5 |
| 475 |
|
*/ |
| 476 |
|
public E remove() { |
| 480 |
|
/** |
| 481 |
|
* Adds the specified element as the tail (last element) of this list. |
| 482 |
|
* |
| 483 |
< |
* @param o the element to add. |
| 484 |
< |
* @return <tt>true</tt> (as per the general contract of |
| 492 |
< |
* <tt>Queue.offer</tt>) |
| 483 |
> |
* @param e the element to add |
| 484 |
> |
* @return <tt>true</tt> (as per the spec for {@link Queue#offer}) |
| 485 |
|
* @since 1.5 |
| 486 |
|
*/ |
| 487 |
< |
public boolean offer(E o) { |
| 488 |
< |
return add(o); |
| 487 |
> |
public boolean offer(E e) { |
| 488 |
> |
return add(e); |
| 489 |
> |
} |
| 490 |
> |
|
| 491 |
> |
// Deque operations |
| 492 |
> |
/** |
| 493 |
> |
* Inserts the specified element at the front of this list. |
| 494 |
> |
* |
| 495 |
> |
* @param e the element to insert |
| 496 |
> |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst}) |
| 497 |
> |
* @since 1.6 |
| 498 |
> |
*/ |
| 499 |
> |
public boolean offerFirst(E e) { |
| 500 |
> |
addFirst(e); |
| 501 |
> |
return true; |
| 502 |
> |
} |
| 503 |
> |
|
| 504 |
> |
/** |
| 505 |
> |
* Inserts the specified element at the end of this list. |
| 506 |
> |
* |
| 507 |
> |
* @param e the element to insert |
| 508 |
> |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast}) |
| 509 |
> |
* @since 1.6 |
| 510 |
> |
*/ |
| 511 |
> |
public boolean offerLast(E e) { |
| 512 |
> |
addLast(e); |
| 513 |
> |
return true; |
| 514 |
> |
} |
| 515 |
> |
|
| 516 |
> |
/** |
| 517 |
> |
* Retrieves, but does not remove, the first element of this list, |
| 518 |
> |
* or returns <tt>null</tt> if this list is empty. |
| 519 |
> |
* |
| 520 |
> |
* @return the first element of this list, or <tt>null</tt> |
| 521 |
> |
* if this list is empty |
| 522 |
> |
* @since 1.6 |
| 523 |
> |
*/ |
| 524 |
> |
public E peekFirst() { |
| 525 |
> |
if (size==0) |
| 526 |
> |
return null; |
| 527 |
> |
return getFirst(); |
| 528 |
> |
} |
| 529 |
> |
|
| 530 |
> |
/** |
| 531 |
> |
* Retrieves, but does not remove, the last element of this list, |
| 532 |
> |
* or returns <tt>null</tt> if this list is empty. |
| 533 |
> |
* |
| 534 |
> |
* @return the last element of this list, or <tt>null</tt> |
| 535 |
> |
* if this list is empty |
| 536 |
> |
* @since 1.6 |
| 537 |
> |
*/ |
| 538 |
> |
public E peekLast() { |
| 539 |
> |
if (size==0) |
| 540 |
> |
return null; |
| 541 |
> |
return getLast(); |
| 542 |
> |
} |
| 543 |
> |
|
| 544 |
> |
/** |
| 545 |
> |
* Retrieves and removes the first element of this list, or |
| 546 |
> |
* <tt>null</tt> if this list is empty. |
| 547 |
> |
* |
| 548 |
> |
* @return the first element of this list, or <tt>null</tt> if |
| 549 |
> |
* this list is empty |
| 550 |
> |
* @since 1.6 |
| 551 |
> |
*/ |
| 552 |
> |
public E pollFirst() { |
| 553 |
> |
if (size==0) |
| 554 |
> |
return null; |
| 555 |
> |
return removeFirst(); |
| 556 |
> |
} |
| 557 |
> |
|
| 558 |
> |
/** |
| 559 |
> |
* Retrieves and removes the last element of this list, or |
| 560 |
> |
* <tt>null</tt> if this list is empty. |
| 561 |
> |
* |
| 562 |
> |
* @return the last element of this list, or <tt>null</tt> if |
| 563 |
> |
* this list is empty |
| 564 |
> |
* @since 1.6 |
| 565 |
> |
*/ |
| 566 |
> |
public E pollLast() { |
| 567 |
> |
if (size==0) |
| 568 |
> |
return null; |
| 569 |
> |
return removeLast(); |
| 570 |
> |
} |
| 571 |
> |
|
| 572 |
> |
/** |
| 573 |
> |
* Pushes an element onto the stack represented by this list. In other |
| 574 |
> |
* words, inserts the element at the front of this list. |
| 575 |
> |
* |
| 576 |
> |
* <p>This method is equivalent to {@link #addFirst}. |
| 577 |
> |
* |
| 578 |
> |
* @param e the element to push |
| 579 |
> |
* @since 1.6 |
| 580 |
> |
*/ |
| 581 |
> |
public void push(E e) { |
| 582 |
> |
addFirst(e); |
| 583 |
> |
} |
| 584 |
> |
|
| 585 |
> |
/** |
| 586 |
> |
* Pops an element from the stack represented by this list. In other |
| 587 |
> |
* words, removes and returns the first element of this list. |
| 588 |
> |
* |
| 589 |
> |
* <p>This method is equivalent to {@link #removeFirst()}. |
| 590 |
> |
* |
| 591 |
> |
* @return the element at the front of this list (which is the top |
| 592 |
> |
* of the stack represented by this list) |
| 593 |
> |
* @throws NoSuchElementException if this list is empty |
| 594 |
> |
* @since 1.6 |
| 595 |
> |
*/ |
| 596 |
> |
public E pop() { |
| 597 |
> |
return removeFirst(); |
| 598 |
> |
} |
| 599 |
> |
|
| 600 |
> |
/** |
| 601 |
> |
* Removes the first occurrence of the specified element in this |
| 602 |
> |
* list (when traversing the list from head to tail). If the list |
| 603 |
> |
* does not contain the element, it is unchanged. |
| 604 |
> |
* |
| 605 |
> |
* @param o element to be removed from this list, if present |
| 606 |
> |
* @return <tt>true</tt> if the list contained the specified element |
| 607 |
> |
* @since 1.6 |
| 608 |
> |
*/ |
| 609 |
> |
public boolean removeFirstOccurrence(Object o) { |
| 610 |
> |
return remove(o); |
| 611 |
> |
} |
| 612 |
> |
|
| 613 |
> |
/** |
| 614 |
> |
* Removes the last occurrence of the specified element in this |
| 615 |
> |
* list (when traversing the list from head to tail). If the list |
| 616 |
> |
* does not contain the element, it is unchanged. |
| 617 |
> |
* |
| 618 |
> |
* @param o element to be removed from this list, if present |
| 619 |
> |
* @return <tt>true</tt> if the list contained the specified element |
| 620 |
> |
* @since 1.6 |
| 621 |
> |
*/ |
| 622 |
> |
public boolean removeLastOccurrence(Object o) { |
| 623 |
> |
if (o==null) { |
| 624 |
> |
for (Entry e = header.previous; e != header; e = e.previous) { |
| 625 |
> |
if (e.element==null) { |
| 626 |
> |
remove(e); |
| 627 |
> |
return true; |
| 628 |
> |
} |
| 629 |
> |
} |
| 630 |
> |
} else { |
| 631 |
> |
for (Entry e = header.previous; e != header; e = e.previous) { |
| 632 |
> |
if (o.equals(e.element)) { |
| 633 |
> |
remove(e); |
| 634 |
> |
return true; |
| 635 |
> |
} |
| 636 |
> |
} |
| 637 |
> |
} |
| 638 |
> |
return false; |
| 639 |
|
} |
| 640 |
|
|
| 641 |
|
/** |
| 652 |
|
* than risking arbitrary, non-deterministic behavior at an undetermined |
| 653 |
|
* time in the future. |
| 654 |
|
* |
| 655 |
< |
* @param index index of first element to be returned from the |
| 656 |
< |
* list-iterator (by a call to <tt>next</tt>). |
| 655 |
> |
* @param index index of the first element to be returned from the |
| 656 |
> |
* list-iterator (by a call to <tt>next</tt>) |
| 657 |
|
* @return a ListIterator of the elements in this list (in proper |
| 658 |
< |
* sequence), starting at the specified position in the list. |
| 659 |
< |
* @throws IndexOutOfBoundsException if index is out of range |
| 518 |
< |
* (<tt>index < 0 || index > size()</tt>). |
| 658 |
> |
* sequence), starting at the specified position in the list |
| 659 |
> |
* @throws IndexOutOfBoundsException {@inheritDoc} |
| 660 |
|
* @see List#listIterator(int) |
| 661 |
|
*/ |
| 662 |
|
public ListIterator<E> listIterator(int index) { |
| 663 |
< |
return new ListItr(index); |
| 663 |
> |
return new ListItr(index); |
| 664 |
|
} |
| 665 |
|
|
| 666 |
|
private class ListItr implements ListIterator<E> { |
| 667 |
< |
private Entry<E> lastReturned = header; |
| 668 |
< |
private Entry<E> next; |
| 669 |
< |
private int nextIndex; |
| 670 |
< |
private int expectedModCount = modCount; |
| 671 |
< |
|
| 672 |
< |
ListItr(int index) { |
| 673 |
< |
if (index < 0 || index > size) |
| 674 |
< |
throw new IndexOutOfBoundsException("Index: "+index+ |
| 675 |
< |
", Size: "+size); |
| 676 |
< |
if (index < (size >> 1)) { |
| 677 |
< |
next = header.next; |
| 678 |
< |
for (nextIndex=0; nextIndex<index; nextIndex++) |
| 679 |
< |
next = next.next; |
| 680 |
< |
} else { |
| 681 |
< |
next = header; |
| 682 |
< |
for (nextIndex=size; nextIndex>index; nextIndex--) |
| 683 |
< |
next = next.previous; |
| 684 |
< |
} |
| 685 |
< |
} |
| 686 |
< |
|
| 687 |
< |
public boolean hasNext() { |
| 688 |
< |
return nextIndex != size; |
| 689 |
< |
} |
| 690 |
< |
|
| 691 |
< |
public E next() { |
| 692 |
< |
checkForComodification(); |
| 693 |
< |
if (nextIndex == size) |
| 694 |
< |
throw new NoSuchElementException(); |
| 695 |
< |
|
| 696 |
< |
lastReturned = next; |
| 697 |
< |
next = next.next; |
| 698 |
< |
nextIndex++; |
| 699 |
< |
return lastReturned.element; |
| 700 |
< |
} |
| 701 |
< |
|
| 702 |
< |
public boolean hasPrevious() { |
| 703 |
< |
return nextIndex != 0; |
| 704 |
< |
} |
| 705 |
< |
|
| 706 |
< |
public E previous() { |
| 707 |
< |
if (nextIndex == 0) |
| 708 |
< |
throw new NoSuchElementException(); |
| 709 |
< |
|
| 710 |
< |
lastReturned = next = next.previous; |
| 711 |
< |
nextIndex--; |
| 712 |
< |
checkForComodification(); |
| 713 |
< |
return lastReturned.element; |
| 714 |
< |
} |
| 715 |
< |
|
| 716 |
< |
public int nextIndex() { |
| 717 |
< |
return nextIndex; |
| 718 |
< |
} |
| 719 |
< |
|
| 720 |
< |
public int previousIndex() { |
| 721 |
< |
return nextIndex-1; |
| 722 |
< |
} |
| 667 |
> |
private Entry<E> lastReturned = header; |
| 668 |
> |
private Entry<E> next; |
| 669 |
> |
private int nextIndex; |
| 670 |
> |
private int expectedModCount = modCount; |
| 671 |
> |
|
| 672 |
> |
ListItr(int index) { |
| 673 |
> |
if (index < 0 || index > size) |
| 674 |
> |
throw new IndexOutOfBoundsException("Index: "+index+ |
| 675 |
> |
", Size: "+size); |
| 676 |
> |
if (index < (size >> 1)) { |
| 677 |
> |
next = header.next; |
| 678 |
> |
for (nextIndex=0; nextIndex<index; nextIndex++) |
| 679 |
> |
next = next.next; |
| 680 |
> |
} else { |
| 681 |
> |
next = header; |
| 682 |
> |
for (nextIndex=size; nextIndex>index; nextIndex--) |
| 683 |
> |
next = next.previous; |
| 684 |
> |
} |
| 685 |
> |
} |
| 686 |
> |
|
| 687 |
> |
public boolean hasNext() { |
| 688 |
> |
return nextIndex != size; |
| 689 |
> |
} |
| 690 |
> |
|
| 691 |
> |
public E next() { |
| 692 |
> |
checkForComodification(); |
| 693 |
> |
if (nextIndex == size) |
| 694 |
> |
throw new NoSuchElementException(); |
| 695 |
> |
|
| 696 |
> |
lastReturned = next; |
| 697 |
> |
next = next.next; |
| 698 |
> |
nextIndex++; |
| 699 |
> |
return lastReturned.element; |
| 700 |
> |
} |
| 701 |
> |
|
| 702 |
> |
public boolean hasPrevious() { |
| 703 |
> |
return nextIndex != 0; |
| 704 |
> |
} |
| 705 |
> |
|
| 706 |
> |
public E previous() { |
| 707 |
> |
if (nextIndex == 0) |
| 708 |
> |
throw new NoSuchElementException(); |
| 709 |
> |
|
| 710 |
> |
lastReturned = next = next.previous; |
| 711 |
> |
nextIndex--; |
| 712 |
> |
checkForComodification(); |
| 713 |
> |
return lastReturned.element; |
| 714 |
> |
} |
| 715 |
> |
|
| 716 |
> |
public int nextIndex() { |
| 717 |
> |
return nextIndex; |
| 718 |
> |
} |
| 719 |
> |
|
| 720 |
> |
public int previousIndex() { |
| 721 |
> |
return nextIndex-1; |
| 722 |
> |
} |
| 723 |
|
|
| 724 |
< |
public void remove() { |
| 724 |
> |
public void remove() { |
| 725 |
|
checkForComodification(); |
| 726 |
+ |
Entry<E> lastNext = lastReturned.next; |
| 727 |
|
try { |
| 728 |
|
LinkedList.this.remove(lastReturned); |
| 729 |
|
} catch (NoSuchElementException e) { |
| 730 |
|
throw new IllegalStateException(); |
| 731 |
|
} |
| 732 |
< |
if (next==lastReturned) |
| 733 |
< |
next = lastReturned.next; |
| 732 |
> |
if (next==lastReturned) |
| 733 |
> |
next = lastNext; |
| 734 |
|
else |
| 735 |
< |
nextIndex--; |
| 736 |
< |
lastReturned = header; |
| 737 |
< |
expectedModCount++; |
| 738 |
< |
} |
| 739 |
< |
|
| 740 |
< |
public void set(E o) { |
| 741 |
< |
if (lastReturned == header) |
| 742 |
< |
throw new IllegalStateException(); |
| 743 |
< |
checkForComodification(); |
| 744 |
< |
lastReturned.element = o; |
| 745 |
< |
} |
| 746 |
< |
|
| 747 |
< |
public void add(E o) { |
| 748 |
< |
checkForComodification(); |
| 749 |
< |
lastReturned = header; |
| 750 |
< |
addBefore(o, next); |
| 751 |
< |
nextIndex++; |
| 752 |
< |
expectedModCount++; |
| 753 |
< |
} |
| 754 |
< |
|
| 755 |
< |
final void checkForComodification() { |
| 756 |
< |
if (modCount != expectedModCount) |
| 757 |
< |
throw new ConcurrentModificationException(); |
| 758 |
< |
} |
| 735 |
> |
nextIndex--; |
| 736 |
> |
lastReturned = header; |
| 737 |
> |
expectedModCount++; |
| 738 |
> |
} |
| 739 |
> |
|
| 740 |
> |
public void set(E e) { |
| 741 |
> |
if (lastReturned == header) |
| 742 |
> |
throw new IllegalStateException(); |
| 743 |
> |
checkForComodification(); |
| 744 |
> |
lastReturned.element = e; |
| 745 |
> |
} |
| 746 |
> |
|
| 747 |
> |
public void add(E e) { |
| 748 |
> |
checkForComodification(); |
| 749 |
> |
lastReturned = header; |
| 750 |
> |
addBefore(e, next); |
| 751 |
> |
nextIndex++; |
| 752 |
> |
expectedModCount++; |
| 753 |
> |
} |
| 754 |
> |
|
| 755 |
> |
final void checkForComodification() { |
| 756 |
> |
if (modCount != expectedModCount) |
| 757 |
> |
throw new ConcurrentModificationException(); |
| 758 |
> |
} |
| 759 |
|
} |
| 760 |
|
|
| 761 |
|
private static class Entry<E> { |
| 762 |
< |
E element; |
| 763 |
< |
Entry<E> next; |
| 764 |
< |
Entry<E> previous; |
| 765 |
< |
|
| 766 |
< |
Entry(E element, Entry<E> next, Entry<E> previous) { |
| 767 |
< |
this.element = element; |
| 768 |
< |
this.next = next; |
| 769 |
< |
this.previous = previous; |
| 770 |
< |
} |
| 771 |
< |
} |
| 772 |
< |
|
| 773 |
< |
private Entry<E> addBefore(E o, Entry<E> e) { |
| 774 |
< |
Entry<E> newEntry = new Entry<E>(o, e, e.previous); |
| 775 |
< |
newEntry.previous.next = newEntry; |
| 776 |
< |
newEntry.next.previous = newEntry; |
| 777 |
< |
size++; |
| 778 |
< |
modCount++; |
| 779 |
< |
return newEntry; |
| 780 |
< |
} |
| 781 |
< |
|
| 782 |
< |
private void remove(Entry<E> e) { |
| 783 |
< |
if (e == header) |
| 784 |
< |
throw new NoSuchElementException(); |
| 785 |
< |
|
| 786 |
< |
e.previous.next = e.next; |
| 787 |
< |
e.next.previous = e.previous; |
| 788 |
< |
size--; |
| 789 |
< |
modCount++; |
| 762 |
> |
E element; |
| 763 |
> |
Entry<E> next; |
| 764 |
> |
Entry<E> previous; |
| 765 |
> |
|
| 766 |
> |
Entry(E element, Entry<E> next, Entry<E> previous) { |
| 767 |
> |
this.element = element; |
| 768 |
> |
this.next = next; |
| 769 |
> |
this.previous = previous; |
| 770 |
> |
} |
| 771 |
> |
} |
| 772 |
> |
|
| 773 |
> |
private Entry<E> addBefore(E e, Entry<E> entry) { |
| 774 |
> |
Entry<E> newEntry = new Entry<E>(e, entry, entry.previous); |
| 775 |
> |
newEntry.previous.next = newEntry; |
| 776 |
> |
newEntry.next.previous = newEntry; |
| 777 |
> |
size++; |
| 778 |
> |
modCount++; |
| 779 |
> |
return newEntry; |
| 780 |
> |
} |
| 781 |
> |
|
| 782 |
> |
private E remove(Entry<E> e) { |
| 783 |
> |
if (e == header) |
| 784 |
> |
throw new NoSuchElementException(); |
| 785 |
> |
|
| 786 |
> |
E result = e.element; |
| 787 |
> |
e.previous.next = e.next; |
| 788 |
> |
e.next.previous = e.previous; |
| 789 |
> |
e.next = e.previous = null; |
| 790 |
> |
e.element = null; |
| 791 |
> |
size--; |
| 792 |
> |
modCount++; |
| 793 |
> |
return result; |
| 794 |
|
} |
| 795 |
|
|
| 796 |
|
/** |
| 797 |
|
* Returns a shallow copy of this <tt>LinkedList</tt>. (The elements |
| 798 |
|
* themselves are not cloned.) |
| 799 |
|
* |
| 800 |
< |
* @return a shallow copy of this <tt>LinkedList</tt> instance. |
| 800 |
> |
* @return a shallow copy of this <tt>LinkedList</tt> instance |
| 801 |
|
*/ |
| 802 |
|
public Object clone() { |
| 803 |
|
LinkedList<E> clone = null; |
| 804 |
< |
try { |
| 805 |
< |
clone = (LinkedList<E>) super.clone(); |
| 806 |
< |
} catch (CloneNotSupportedException e) { |
| 807 |
< |
throw new InternalError(); |
| 808 |
< |
} |
| 804 |
> |
try { |
| 805 |
> |
clone = (LinkedList<E>) super.clone(); |
| 806 |
> |
} catch (CloneNotSupportedException e) { |
| 807 |
> |
throw new InternalError(); |
| 808 |
> |
} |
| 809 |
|
|
| 810 |
|
// Put clone into "virgin" state |
| 811 |
|
clone.header = new Entry<E>(null, null, null); |
| 822 |
|
|
| 823 |
|
/** |
| 824 |
|
* Returns an array containing all of the elements in this list |
| 825 |
< |
* in the correct order. |
| 825 |
> |
* in proper sequence (from first to last element). |
| 826 |
> |
* |
| 827 |
> |
* <p>The returned array will be "safe" in that no references to it are |
| 828 |
> |
* maintained by this list. (In other words, this method must allocate |
| 829 |
> |
* a new array). The caller is thus free to modify the returned array. |
| 830 |
> |
* |
| 831 |
> |
* <p>This method acts as bridge between array-based and collection-based |
| 832 |
> |
* APIs. |
| 833 |
|
* |
| 834 |
|
* @return an array containing all of the elements in this list |
| 835 |
< |
* in the correct order. |
| 835 |
> |
* in proper sequence |
| 836 |
|
*/ |
| 837 |
|
public Object[] toArray() { |
| 838 |
< |
Object[] result = new Object[size]; |
| 838 |
> |
Object[] result = new Object[size]; |
| 839 |
|
int i = 0; |
| 840 |
|
for (Entry<E> e = header.next; e != header; e = e.next) |
| 841 |
|
result[i++] = e.element; |
| 842 |
< |
return result; |
| 842 |
> |
return result; |
| 843 |
|
} |
| 844 |
|
|
| 845 |
|
/** |
| 846 |
|
* Returns an array containing all of the elements in this list in |
| 847 |
< |
* the correct order; the runtime type of the returned array is that of |
| 848 |
< |
* the specified array. If the list fits in the specified array, it |
| 849 |
< |
* is returned therein. Otherwise, a new array is allocated with the |
| 850 |
< |
* runtime type of the specified array and the size of this list.<p> |
| 851 |
< |
* |
| 852 |
< |
* If the list fits in the specified array with room to spare |
| 853 |
< |
* (i.e., the array has more elements than the list), |
| 854 |
< |
* the element in the array immediately following the end of the |
| 855 |
< |
* collection is set to null. This is useful in determining the length |
| 856 |
< |
* of the list <i>only</i> if the caller knows that the list |
| 857 |
< |
* does not contain any null elements. |
| 847 |
> |
* proper sequence (from first to last element); the runtime type of |
| 848 |
> |
* the returned array is that of the specified array. If the list fits |
| 849 |
> |
* in the specified array, it is returned therein. Otherwise, a new |
| 850 |
> |
* array is allocated with the runtime type of the specified array and |
| 851 |
> |
* the size of this list. |
| 852 |
> |
* |
| 853 |
> |
* <p>If the list fits in the specified array with room to spare (i.e., |
| 854 |
> |
* the array has more elements than the list), the element in the array |
| 855 |
> |
* immediately following the end of the list is set to <tt>null</tt>. |
| 856 |
> |
* (This is useful in determining the length of the list <i>only</i> if |
| 857 |
> |
* the caller knows that the list does not contain any null elements.) |
| 858 |
> |
* |
| 859 |
> |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
| 860 |
> |
* array-based and collection-based APIs. Further, this method allows |
| 861 |
> |
* precise control over the runtime type of the output array, and may, |
| 862 |
> |
* under certain circumstances, be used to save allocation costs. |
| 863 |
> |
* |
| 864 |
> |
* <p>Suppose <tt>x</tt> is a list known to contain only strings. |
| 865 |
> |
* The following code can be used to dump the list into a newly |
| 866 |
> |
* allocated array of <tt>String</tt>: |
| 867 |
> |
* |
| 868 |
> |
* <pre> |
| 869 |
> |
* String[] y = x.toArray(new String[0]);</pre> |
| 870 |
> |
* |
| 871 |
> |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
| 872 |
> |
* <tt>toArray()</tt>. |
| 873 |
|
* |
| 874 |
|
* @param a the array into which the elements of the list are to |
| 875 |
|
* be stored, if it is big enough; otherwise, a new array of the |
| 876 |
|
* same runtime type is allocated for this purpose. |
| 877 |
< |
* @return an array containing the elements of the list. |
| 878 |
< |
* @throws ArrayStoreException if the runtime type of a is not a |
| 879 |
< |
* supertype of the runtime type of every element in this list. |
| 880 |
< |
* @throws NullPointerException if the specified array is null. |
| 877 |
> |
* @return an array containing the elements of the list |
| 878 |
> |
* @throws ArrayStoreException if the runtime type of the specified array |
| 879 |
> |
* is not a supertype of the runtime type of every element in |
| 880 |
> |
* this list |
| 881 |
> |
* @throws NullPointerException if the specified array is null |
| 882 |
|
*/ |
| 883 |
|
public <T> T[] toArray(T[] a) { |
| 884 |
|
if (a.length < size) |
| 885 |
|
a = (T[])java.lang.reflect.Array.newInstance( |
| 886 |
|
a.getClass().getComponentType(), size); |
| 887 |
|
int i = 0; |
| 888 |
< |
Object[] result = a; |
| 888 |
> |
Object[] result = a; |
| 889 |
|
for (Entry<E> e = header.next; e != header; e = e.next) |
| 890 |
|
result[i++] = e.element; |
| 891 |
|
|
| 903 |
|
* |
| 904 |
|
* @serialData The size of the list (the number of elements it |
| 905 |
|
* contains) is emitted (int), followed by all of its |
| 906 |
< |
* elements (each an Object) in the proper order. |
| 906 |
> |
* elements (each an Object) in the proper order. |
| 907 |
|
*/ |
| 908 |
|
private void writeObject(java.io.ObjectOutputStream s) |
| 909 |
|
throws java.io.IOException { |
| 910 |
< |
// Write out any hidden serialization magic |
| 911 |
< |
s.defaultWriteObject(); |
| 910 |
> |
// Write out any hidden serialization magic |
| 911 |
> |
s.defaultWriteObject(); |
| 912 |
|
|
| 913 |
|
// Write out size |
| 914 |
|
s.writeInt(size); |
| 915 |
|
|
| 916 |
< |
// Write out all elements in the proper order. |
| 916 |
> |
// Write out all elements in the proper order. |
| 917 |
|
for (Entry e = header.next; e != header; e = e.next) |
| 918 |
|
s.writeObject(e.element); |
| 919 |
|
} |
| 924 |
|
*/ |
| 925 |
|
private void readObject(java.io.ObjectInputStream s) |
| 926 |
|
throws java.io.IOException, ClassNotFoundException { |
| 927 |
< |
// Read in any hidden serialization magic |
| 928 |
< |
s.defaultReadObject(); |
| 927 |
> |
// Read in any hidden serialization magic |
| 928 |
> |
s.defaultReadObject(); |
| 929 |
|
|
| 930 |
|
// Read in size |
| 931 |
|
int size = s.readInt(); |
| 934 |
|
header = new Entry<E>(null, null, null); |
| 935 |
|
header.next = header.previous = header; |
| 936 |
|
|
| 937 |
< |
// Read in all elements in the proper order. |
| 938 |
< |
for (int i=0; i<size; i++) |
| 937 |
> |
// Read in all elements in the proper order. |
| 938 |
> |
for (int i=0; i<size; i++) |
| 939 |
|
addBefore((E)s.readObject(), header); |
| 940 |
|
} |
| 941 |
|
} |
