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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 |
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* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> (if such an |
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* element exists). |
199 |
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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 |
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* <tt>i</tt> such that |
203 |
> |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
204 |
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* (if such an element exists). Returns <tt>true</tt> if this list |
205 |
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* contained the specified element (or equivalently, if this list |
206 |
> |
* changed as a result of the call). |
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* |
208 |
< |
* @param o element to be removed from this list, if present. |
209 |
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* @return <tt>true</tt> if the list contained the specified element. |
208 |
> |
* @param o element to be removed from this list, if present |
209 |
> |
* @return <tt>true</tt> if this list contained the specified element |
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*/ |
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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 |
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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 |
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* @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) { |
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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 |
258 |
> |
* @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) { |
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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) |
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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++) { |
273 |
> |
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 |
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header.next = header.previous = header; |
296 |
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size = 0; |
297 |
+ |
modCount++; |
298 |
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} |
299 |
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|
300 |
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|
303 |
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/** |
304 |
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* Returns the element at the specified position in this list. |
305 |
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* |
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 |
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*/ |
310 |
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public E get(int index) { |
311 |
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return entry(index).element; |
315 |
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* Replaces the element at the specified position in this list with the |
316 |
|
* specified element. |
317 |
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* |
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 |
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public E set(int index, E element) { |
324 |
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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 |
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* |
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 |
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* 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 |
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|
356 |
|
/** |
357 |
< |
* Return the indexed entry. |
357 |
> |
* Returns the indexed entry. |
358 |
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*/ |
359 |
|
private Entry<E> entry(int index) { |
360 |
|
if (index < 0 || index >= size) |
375 |
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// Search Operations |
376 |
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|
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(); |
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 |
< |
lastReturned = next; |
556 |
< |
next = next.next; |
557 |
< |
nextIndex++; |
558 |
< |
return lastReturned.element; |
559 |
< |
} |
560 |
< |
|
561 |
< |
public boolean hasPrevious() { |
562 |
< |
return nextIndex != 0; |
563 |
< |
} |
564 |
< |
|
565 |
< |
public E previous() { |
566 |
< |
if (nextIndex == 0) |
567 |
< |
throw new NoSuchElementException(); |
568 |
< |
|
569 |
< |
lastReturned = next = next.previous; |
570 |
< |
nextIndex--; |
571 |
< |
checkForComodification(); |
572 |
< |
return lastReturned.element; |
573 |
< |
} |
574 |
< |
|
575 |
< |
public int nextIndex() { |
576 |
< |
return nextIndex; |
577 |
< |
} |
578 |
< |
|
579 |
< |
public int previousIndex() { |
580 |
< |
return nextIndex-1; |
581 |
< |
} |
582 |
< |
|
583 |
< |
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 |
|
} |