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/* |
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* @(#)LinkedList.java 1.43 01/12/03 |
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* %W% %E% |
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* |
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* Copyright 2002 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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package java.util; |
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/** |
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* <b>JSR166: Added Queue operations</b>.<p> |
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* Linked list implementation of the <tt>List</tt> interface. Implements all |
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* optional list operations, and permits all elements (including |
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* <tt>null</tt>). In addition to implementing the <tt>List</tt> interface, |
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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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* All of the stack/queue/deque operations could be easily recast in terms of |
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* the standard list operations. They're included here primarily for |
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* convenience, though they may run slightly faster than the equivalent List |
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* operations.<p> |
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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>, 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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* the begining or the end, whichever is closer to the specified index.<p> |
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* the beginning or the end, whichever is closer to the specified index.<p> |
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* |
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* <b>Note that this implementation is not synchronized.</b> If multiple |
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* threads access a list concurrently, and at least one of the threads |
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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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* presence of unsynchronized concurrent modification. Fail-fast iterators |
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* throw <tt>ConcurrentModificationException</tt> on a best-effort basis. |
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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> |
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* |
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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 1.43, 12/03/01 |
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* @see java.util.List |
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* @see java.util.ArrayList |
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* @see java.util.Vector |
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* @see java.util.Collections#synchronizedList(java.util.List) |
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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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* @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 extends AbstractSequentialList |
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implements List, Queue, Cloneable, java.io.Serializable |
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public class LinkedList<E> |
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extends AbstractSequentialList<E> |
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implements List<E>, Deque<E>, Cloneable, java.io.Serializable |
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{ |
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private transient Entry header = new Entry(null, null, null); |
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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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|
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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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*/ |
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public LinkedList(Collection c) { |
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this(); |
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addAll(c); |
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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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* @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 Object getFirst() { |
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if (size==0) |
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throw new NoSuchElementException(); |
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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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|
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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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* @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 Object getLast() { |
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if (size==0) |
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throw new NoSuchElementException(); |
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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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|
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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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* @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 Object removeFirst() { |
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Object first = header.next.element; |
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remove(header.next); |
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return first; |
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public E removeFirst() { |
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return remove(header.next); |
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} |
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|
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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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*/ |
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public Object removeLast() { |
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Object last = header.previous.element; |
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remove(header.previous); |
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return last; |
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public E removeLast() { |
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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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* |
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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(Object 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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* |
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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(Object 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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* @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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* @param e 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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*/ |
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public boolean add(Object 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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public boolean remove(Object o) { |
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if (o==null) { |
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for (Entry e = header.next; e != header; e = e.next) { |
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for (Entry<E> e = header.next; e != header; e = e.next) { |
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if (e.element==null) { |
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remove(e); |
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return true; |
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} |
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} |
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} else { |
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for (Entry e = header.next; e != header; e = e.next) { |
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for (Entry<E> e = header.next; e != header; e = e.next) { |
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if (o.equals(e.element)) { |
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remove(e); |
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return true; |
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* @return <tt>true</tt> if this list changed as a result of the call. |
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* @throws NullPointerException if the specified collection is null. |
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*/ |
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public boolean addAll(Collection c) { |
240 |
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public boolean addAll(Collection<? extends E> c) { |
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return addAll(size, c); |
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} |
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|
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* specified collection's iterator. |
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* |
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* @param index index at which to insert first element |
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* from the specified collection. |
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* from the specified collection. |
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* @param c elements to be inserted into this list. |
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* @return <tt>true</tt> if this list changed as a result of the call. |
256 |
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* @throws IndexOutOfBoundsException if the specified index is out of |
257 |
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* range (<tt>index < 0 || index > size()</tt>). |
256 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
257 |
> |
* (<tt>index < 0 || index > size()</tt>). |
258 |
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* @throws NullPointerException if the specified collection is null. |
259 |
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*/ |
260 |
< |
public boolean addAll(int index, Collection c) { |
261 |
< |
int numNew = c.size(); |
262 |
< |
if (numNew==0) { |
263 |
< |
if (index < 0 || index >= size) |
264 |
< |
throw new IndexOutOfBoundsException(); |
265 |
< |
else |
266 |
< |
return false; |
267 |
< |
} |
268 |
< |
modCount++; |
269 |
< |
|
270 |
< |
Entry successor = (index==size ? header : entry(index)); |
271 |
< |
Entry predecessor = successor.previous; |
272 |
< |
Iterator it = c.iterator(); |
273 |
< |
for (int i=0; i<numNew; i++) { |
272 |
< |
Entry e = new Entry(it.next(), successor, predecessor); |
260 |
> |
public boolean addAll(int index, Collection<? extends E> c) { |
261 |
> |
if (index < 0 || index > size) |
262 |
> |
throw new IndexOutOfBoundsException("Index: "+index+ |
263 |
> |
", Size: "+size); |
264 |
> |
Object[] a = c.toArray(); |
265 |
> |
int numNew = a.length; |
266 |
> |
if (numNew==0) |
267 |
> |
return false; |
268 |
> |
modCount++; |
269 |
> |
|
270 |
> |
Entry<E> successor = (index==size ? header : entry(index)); |
271 |
> |
Entry<E> predecessor = successor.previous; |
272 |
> |
for (int i=0; i<numNew; i++) { |
273 |
> |
Entry<E> e = new Entry<E>((E)a[i], successor, predecessor); |
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predecessor.next = e; |
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predecessor = e; |
276 |
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} |
284 |
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* Removes all of the elements from this list. |
285 |
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*/ |
286 |
|
public void clear() { |
287 |
< |
modCount++; |
287 |
> |
Entry<E> e = header.next; |
288 |
> |
while (e != header) { |
289 |
> |
Entry<E> next = e.next; |
290 |
> |
e.next = e.previous = null; |
291 |
> |
e.element = null; |
292 |
> |
e = next; |
293 |
> |
} |
294 |
|
header.next = header.previous = header; |
295 |
|
size = 0; |
296 |
+ |
modCount++; |
297 |
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} |
298 |
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|
299 |
|
|
304 |
|
* |
305 |
|
* @param index index of element to return. |
306 |
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* @return the element at the specified position in this list. |
307 |
< |
* |
308 |
< |
* @throws IndexOutOfBoundsException if the specified index is is out of |
309 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
307 |
> |
* |
308 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
309 |
> |
* (<tt>index < 0 || index > size()</tt>). |
310 |
|
*/ |
311 |
< |
public Object get(int index) { |
311 |
> |
public E get(int index) { |
312 |
|
return entry(index).element; |
313 |
|
} |
314 |
|
|
319 |
|
* @param index index of element to replace. |
320 |
|
* @param element element to be stored at the specified position. |
321 |
|
* @return the element previously at the specified position. |
322 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
323 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
322 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
323 |
> |
* (<tt>index < 0 || index > size()</tt>). |
324 |
|
*/ |
325 |
< |
public Object set(int index, Object element) { |
326 |
< |
Entry e = entry(index); |
327 |
< |
Object oldVal = e.element; |
325 |
> |
public E set(int index, E element) { |
326 |
> |
Entry<E> e = entry(index); |
327 |
> |
E oldVal = e.element; |
328 |
|
e.element = element; |
329 |
|
return oldVal; |
330 |
|
} |
336 |
|
* |
337 |
|
* @param index index at which the specified element is to be inserted. |
338 |
|
* @param element element to be inserted. |
339 |
< |
* |
340 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
341 |
< |
* range (<tt>index < 0 || index > size()</tt>). |
339 |
> |
* |
340 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
341 |
> |
* (<tt>index < 0 || index > size()</tt>). |
342 |
|
*/ |
343 |
< |
public void add(int index, Object element) { |
343 |
> |
public void add(int index, E element) { |
344 |
|
addBefore(element, (index==size ? header : entry(index))); |
345 |
|
} |
346 |
|
|
351 |
|
* |
352 |
|
* @param index the index of the element to removed. |
353 |
|
* @return the element previously at the specified position. |
354 |
< |
* |
355 |
< |
* @throws IndexOutOfBoundsException if the specified index is out of |
356 |
< |
* range (<tt>index < 0 || index >= size()</tt>). |
354 |
> |
* |
355 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
356 |
> |
* (<tt>index < 0 || index > size()</tt>). |
357 |
|
*/ |
358 |
< |
public Object remove(int index) { |
359 |
< |
Entry e = entry(index); |
352 |
< |
remove(e); |
353 |
< |
return e.element; |
358 |
> |
public E remove(int index) { |
359 |
> |
return remove(entry(index)); |
360 |
|
} |
361 |
|
|
362 |
|
/** |
363 |
< |
* Return the indexed entry. |
363 |
> |
* Returns the indexed entry. |
364 |
|
*/ |
365 |
< |
private Entry entry(int index) { |
365 |
> |
private Entry<E> entry(int index) { |
366 |
|
if (index < 0 || index >= size) |
367 |
|
throw new IndexOutOfBoundsException("Index: "+index+ |
368 |
|
", Size: "+size); |
369 |
< |
Entry e = header; |
369 |
> |
Entry<E> e = header; |
370 |
|
if (index < (size >> 1)) { |
371 |
|
for (int i = 0; i <= index; i++) |
372 |
|
e = e.next; |
389 |
|
* |
390 |
|
* @param o element to search for. |
391 |
|
* @return the index in this list of the first occurrence of the |
392 |
< |
* specified element, or -1 if the list does not contain this |
393 |
< |
* element. |
392 |
> |
* specified element, or -1 if the list does not contain this |
393 |
> |
* element. |
394 |
|
*/ |
395 |
|
public int indexOf(Object o) { |
396 |
|
int index = 0; |
419 |
|
* |
420 |
|
* @param o element to search for. |
421 |
|
* @return the index in this list of the last occurrence of the |
422 |
< |
* specified element, or -1 if the list does not contain this |
423 |
< |
* element. |
422 |
> |
* specified element, or -1 if the list does not contain this |
423 |
> |
* element. |
424 |
|
*/ |
425 |
|
public int lastIndexOf(Object o) { |
426 |
|
int index = size; |
440 |
|
return -1; |
441 |
|
} |
442 |
|
|
443 |
+ |
// Queue operations. |
444 |
+ |
|
445 |
+ |
/** |
446 |
+ |
* Retrieves, but does not remove, the head (first element) of this list. |
447 |
+ |
* @return the head of this list, or <tt>null</tt> if this list is empty. |
448 |
+ |
* @since 1.5 |
449 |
+ |
*/ |
450 |
+ |
public E peek() { |
451 |
+ |
if (size==0) |
452 |
+ |
return null; |
453 |
+ |
return getFirst(); |
454 |
+ |
} |
455 |
+ |
|
456 |
+ |
/** |
457 |
+ |
* Retrieves, but does not remove, the head (first element) of this list. |
458 |
+ |
* @return the head of this list. |
459 |
+ |
* @throws NoSuchElementException if this list is empty. |
460 |
+ |
* @since 1.5 |
461 |
+ |
*/ |
462 |
+ |
public E element() { |
463 |
+ |
return getFirst(); |
464 |
+ |
} |
465 |
+ |
|
466 |
+ |
/** |
467 |
+ |
* Retrieves and removes the head (first element) of this list. |
468 |
+ |
* @return the head of this list, or <tt>null</tt> if this list is empty. |
469 |
+ |
* @since 1.5 |
470 |
+ |
*/ |
471 |
+ |
public E poll() { |
472 |
+ |
if (size==0) |
473 |
+ |
return null; |
474 |
+ |
return removeFirst(); |
475 |
+ |
} |
476 |
+ |
|
477 |
+ |
/** |
478 |
+ |
* Retrieves and removes the head (first element) of this list. |
479 |
+ |
* @return the head of this list. |
480 |
+ |
* @throws NoSuchElementException if this list is empty. |
481 |
+ |
* @since 1.5 |
482 |
+ |
*/ |
483 |
+ |
public E remove() { |
484 |
+ |
return removeFirst(); |
485 |
+ |
} |
486 |
+ |
|
487 |
+ |
/** |
488 |
+ |
* Adds the specified element as the tail (last element) of this list. |
489 |
+ |
* |
490 |
+ |
* @param e the element to add. |
491 |
+ |
* @return <tt>true</tt> (as per the general contract of |
492 |
+ |
* <tt>Queue.offer</tt>) |
493 |
+ |
* @since 1.5 |
494 |
+ |
*/ |
495 |
+ |
public boolean offer(E e) { |
496 |
+ |
return add(e); |
497 |
+ |
} |
498 |
+ |
|
499 |
+ |
// Deque operations |
500 |
+ |
/** |
501 |
+ |
* Inserts the specified element at the front of this list. |
502 |
+ |
* |
503 |
+ |
* @param e the element to insert |
504 |
+ |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerFirst}) |
505 |
+ |
* @since 1.6 |
506 |
+ |
*/ |
507 |
+ |
public boolean offerFirst(E e) { |
508 |
+ |
addFirst(e); |
509 |
+ |
return true; |
510 |
+ |
} |
511 |
+ |
|
512 |
+ |
/** |
513 |
+ |
* Inserts the specified element at the end of this list. |
514 |
+ |
* |
515 |
+ |
* @param e the element to insert |
516 |
+ |
* @return <tt>true</tt> (as per the spec for {@link Deque#offerLast}) |
517 |
+ |
* @since 1.6 |
518 |
+ |
*/ |
519 |
+ |
public boolean offerLast(E e) { |
520 |
+ |
addLast(e); |
521 |
+ |
return true; |
522 |
+ |
} |
523 |
+ |
|
524 |
+ |
/** |
525 |
+ |
* Retrieves, but does not remove, the first element of this list, |
526 |
+ |
* returning <tt>null</tt> if this list is empty. |
527 |
+ |
* |
528 |
+ |
* @return the first element of this list, or <tt>null</tt> if |
529 |
+ |
* this list is empty |
530 |
+ |
* @since 1.6 |
531 |
+ |
*/ |
532 |
+ |
public E peekFirst() { |
533 |
+ |
if (size==0) |
534 |
+ |
return null; |
535 |
+ |
return getFirst(); |
536 |
+ |
} |
537 |
+ |
|
538 |
+ |
/** |
539 |
+ |
* Retrieves, but does not remove, the last element of this list, |
540 |
+ |
* returning <tt>null</tt> if this list is empty. |
541 |
+ |
* |
542 |
+ |
* @return the last element of this list, or <tt>null</tt> if this list |
543 |
+ |
* is empty |
544 |
+ |
* @since 1.6 |
545 |
+ |
*/ |
546 |
+ |
public E peekLast() { |
547 |
+ |
if (size==0) |
548 |
+ |
return null; |
549 |
+ |
return getLast(); |
550 |
+ |
} |
551 |
+ |
|
552 |
+ |
/** |
553 |
+ |
* Retrieves and removes the first element of this list, or |
554 |
+ |
* <tt>null</tt> if this list is empty. |
555 |
+ |
* |
556 |
+ |
* @return the first element of this list, or <tt>null</tt> if |
557 |
+ |
* this list is empty |
558 |
+ |
* @since 1.6 |
559 |
+ |
*/ |
560 |
+ |
public E pollFirst() { |
561 |
+ |
if (size==0) |
562 |
+ |
return null; |
563 |
+ |
return removeFirst(); |
564 |
+ |
} |
565 |
+ |
|
566 |
+ |
/** |
567 |
+ |
* Retrieves and removes the last element of this list, or |
568 |
+ |
* <tt>null</tt> if this list is empty. |
569 |
+ |
* |
570 |
+ |
* @return the last element of this list, or <tt>null</tt> if |
571 |
+ |
* this list is empty |
572 |
+ |
* @since 1.6 |
573 |
+ |
*/ |
574 |
+ |
public E pollLast() { |
575 |
+ |
if (size==0) |
576 |
+ |
return null; |
577 |
+ |
return removeLast(); |
578 |
+ |
} |
579 |
+ |
|
580 |
+ |
/** |
581 |
+ |
* Pushes an element onto the stack represented by this list. In other |
582 |
+ |
* words, inserts the element at the front of this list. |
583 |
+ |
* |
584 |
+ |
* <p>This method is equivalent to {@link #addFirst}. |
585 |
+ |
* |
586 |
+ |
* @param e the element to push |
587 |
+ |
* @since 1.6 |
588 |
+ |
*/ |
589 |
+ |
public void push(E e) { |
590 |
+ |
addFirst(e); |
591 |
+ |
} |
592 |
+ |
|
593 |
+ |
/** |
594 |
+ |
* Pops an element from the stack represented by this list. In other |
595 |
+ |
* words, removes and returns the first element of this list. |
596 |
+ |
* |
597 |
+ |
* <p>This method is equivalent to {@link #removeFirst()}. |
598 |
+ |
* |
599 |
+ |
* @return the element at the front of this list (which is the top |
600 |
+ |
* of the stack represented by this list) |
601 |
+ |
* @throws NoSuchElementException if this list is empty. |
602 |
+ |
* @since 1.6 |
603 |
+ |
*/ |
604 |
+ |
public E pop() { |
605 |
+ |
return removeFirst(); |
606 |
+ |
} |
607 |
+ |
|
608 |
+ |
/** |
609 |
+ |
* Removes the first occurrence of the specified element in this |
610 |
+ |
* list (when traversing the list from head to tail). If the list |
611 |
+ |
* does not contain the element, it is unchanged. |
612 |
+ |
* |
613 |
+ |
* @param o element to be removed from this list, if present |
614 |
+ |
* @return <tt>true</tt> if the list contained the specified element |
615 |
+ |
* @since 1.6 |
616 |
+ |
*/ |
617 |
+ |
public boolean removeFirstOccurrence(Object o) { |
618 |
+ |
return remove(o); |
619 |
+ |
} |
620 |
+ |
|
621 |
+ |
/** |
622 |
+ |
* Removes the last occurrence of the specified element in this |
623 |
+ |
* list (when traversing the list from head to tail). If the list |
624 |
+ |
* does not contain the element, it is unchanged. |
625 |
+ |
* |
626 |
+ |
* @param o element to be removed from this list, if present |
627 |
+ |
* @return <tt>true</tt> if the list contained the specified element |
628 |
+ |
* @since 1.6 |
629 |
+ |
*/ |
630 |
+ |
public boolean removeLastOccurrence(Object o) { |
631 |
+ |
if (o==null) { |
632 |
+ |
for (Entry e = header.previous; e != header; e = e.previous) { |
633 |
+ |
if (e.element==null) { |
634 |
+ |
remove(e); |
635 |
+ |
return true; |
636 |
+ |
} |
637 |
+ |
} |
638 |
+ |
} else { |
639 |
+ |
for (Entry e = header.previous; e != header; e = e.previous) { |
640 |
+ |
if (o.equals(e.element)) { |
641 |
+ |
remove(e); |
642 |
+ |
return true; |
643 |
+ |
} |
644 |
+ |
} |
645 |
+ |
} |
646 |
+ |
return false; |
647 |
+ |
} |
648 |
+ |
|
649 |
|
/** |
650 |
|
* Returns a list-iterator of the elements in this list (in proper |
651 |
|
* sequence), starting at the specified position in the list. |
661 |
|
* time in the future. |
662 |
|
* |
663 |
|
* @param index index of first element to be returned from the |
664 |
< |
* list-iterator (by a call to <tt>next</tt>). |
664 |
> |
* list-iterator (by a call to <tt>next</tt>). |
665 |
|
* @return a ListIterator of the elements in this list (in proper |
666 |
< |
* sequence), starting at the specified position in the list. |
667 |
< |
* @throws IndexOutOfBoundsException if index is out of range |
668 |
< |
* (<tt>index < 0 || index > size()</tt>). |
669 |
< |
* @see java.util.List#listIterator(int) |
670 |
< |
*/ |
671 |
< |
public ListIterator listIterator(int index) { |
672 |
< |
return new ListItr(index); |
673 |
< |
} |
674 |
< |
|
675 |
< |
private class ListItr implements ListIterator { |
676 |
< |
private Entry lastReturned = header; |
677 |
< |
private Entry next; |
678 |
< |
private int nextIndex; |
679 |
< |
private int expectedModCount = modCount; |
680 |
< |
|
681 |
< |
ListItr(int index) { |
682 |
< |
if (index < 0 || index > size) |
683 |
< |
throw new IndexOutOfBoundsException("Index: "+index+ |
684 |
< |
", Size: "+size); |
685 |
< |
if (index < (size >> 1)) { |
686 |
< |
next = header.next; |
687 |
< |
for (nextIndex=0; nextIndex<index; nextIndex++) |
688 |
< |
next = next.next; |
689 |
< |
} else { |
690 |
< |
next = header; |
691 |
< |
for (nextIndex=size; nextIndex>index; nextIndex--) |
692 |
< |
next = next.previous; |
693 |
< |
} |
694 |
< |
} |
666 |
> |
* sequence), starting at the specified position in the list. |
667 |
> |
* @throws IndexOutOfBoundsException if the index is out of range |
668 |
> |
* (<tt>index < 0 || index > size()</tt>). |
669 |
> |
* @see List#listIterator(int) |
670 |
> |
*/ |
671 |
> |
public ListIterator<E> listIterator(int index) { |
672 |
> |
return new ListItr(index); |
673 |
> |
} |
674 |
> |
|
675 |
> |
private class ListItr implements ListIterator<E> { |
676 |
> |
private Entry<E> lastReturned = header; |
677 |
> |
private Entry<E> next; |
678 |
> |
private int nextIndex; |
679 |
> |
private int expectedModCount = modCount; |
680 |
> |
|
681 |
> |
ListItr(int index) { |
682 |
> |
if (index < 0 || index > size) |
683 |
> |
throw new IndexOutOfBoundsException("Index: "+index+ |
684 |
> |
", Size: "+size); |
685 |
> |
if (index < (size >> 1)) { |
686 |
> |
next = header.next; |
687 |
> |
for (nextIndex=0; nextIndex<index; nextIndex++) |
688 |
> |
next = next.next; |
689 |
> |
} else { |
690 |
> |
next = header; |
691 |
> |
for (nextIndex=size; nextIndex>index; nextIndex--) |
692 |
> |
next = next.previous; |
693 |
> |
} |
694 |
> |
} |
695 |
> |
|
696 |
> |
public boolean hasNext() { |
697 |
> |
return nextIndex != size; |
698 |
> |
} |
699 |
> |
|
700 |
> |
public E next() { |
701 |
> |
checkForComodification(); |
702 |
> |
if (nextIndex == size) |
703 |
> |
throw new NoSuchElementException(); |
704 |
> |
|
705 |
> |
lastReturned = next; |
706 |
> |
next = next.next; |
707 |
> |
nextIndex++; |
708 |
> |
return lastReturned.element; |
709 |
> |
} |
710 |
> |
|
711 |
> |
public boolean hasPrevious() { |
712 |
> |
return nextIndex != 0; |
713 |
> |
} |
714 |
> |
|
715 |
> |
public E previous() { |
716 |
> |
if (nextIndex == 0) |
717 |
> |
throw new NoSuchElementException(); |
718 |
> |
|
719 |
> |
lastReturned = next = next.previous; |
720 |
> |
nextIndex--; |
721 |
> |
checkForComodification(); |
722 |
> |
return lastReturned.element; |
723 |
> |
} |
724 |
> |
|
725 |
> |
public int nextIndex() { |
726 |
> |
return nextIndex; |
727 |
> |
} |
728 |
> |
|
729 |
> |
public int previousIndex() { |
730 |
> |
return nextIndex-1; |
731 |
> |
} |
732 |
|
|
733 |
< |
public boolean hasNext() { |
485 |
< |
return nextIndex != size; |
486 |
< |
} |
487 |
< |
|
488 |
< |
public Object next() { |
489 |
< |
checkForComodification(); |
490 |
< |
if (nextIndex == size) |
491 |
< |
throw new NoSuchElementException(); |
492 |
< |
|
493 |
< |
lastReturned = next; |
494 |
< |
next = next.next; |
495 |
< |
nextIndex++; |
496 |
< |
return lastReturned.element; |
497 |
< |
} |
498 |
< |
|
499 |
< |
public boolean hasPrevious() { |
500 |
< |
return nextIndex != 0; |
501 |
< |
} |
502 |
< |
|
503 |
< |
public Object previous() { |
504 |
< |
if (nextIndex == 0) |
505 |
< |
throw new NoSuchElementException(); |
506 |
< |
|
507 |
< |
lastReturned = next = next.previous; |
508 |
< |
nextIndex--; |
509 |
< |
checkForComodification(); |
510 |
< |
return lastReturned.element; |
511 |
< |
} |
512 |
< |
|
513 |
< |
public int nextIndex() { |
514 |
< |
return nextIndex; |
515 |
< |
} |
516 |
< |
|
517 |
< |
public int previousIndex() { |
518 |
< |
return nextIndex-1; |
519 |
< |
} |
520 |
< |
|
521 |
< |
public void remove() { |
733 |
> |
public void remove() { |
734 |
|
checkForComodification(); |
735 |
+ |
Entry<E> lastNext = lastReturned.next; |
736 |
|
try { |
737 |
|
LinkedList.this.remove(lastReturned); |
738 |
|
} catch (NoSuchElementException e) { |
739 |
|
throw new IllegalStateException(); |
740 |
|
} |
741 |
< |
if (next==lastReturned) |
742 |
< |
next = lastReturned.next; |
741 |
> |
if (next==lastReturned) |
742 |
> |
next = lastNext; |
743 |
|
else |
744 |
< |
nextIndex--; |
745 |
< |
lastReturned = header; |
746 |
< |
expectedModCount++; |
747 |
< |
} |
748 |
< |
|
749 |
< |
public void set(Object o) { |
750 |
< |
if (lastReturned == header) |
751 |
< |
throw new IllegalStateException(); |
752 |
< |
checkForComodification(); |
753 |
< |
lastReturned.element = o; |
754 |
< |
} |
755 |
< |
|
756 |
< |
public void add(Object o) { |
757 |
< |
checkForComodification(); |
758 |
< |
lastReturned = header; |
759 |
< |
addBefore(o, next); |
760 |
< |
nextIndex++; |
761 |
< |
expectedModCount++; |
762 |
< |
} |
763 |
< |
|
764 |
< |
final void checkForComodification() { |
765 |
< |
if (modCount != expectedModCount) |
766 |
< |
throw new ConcurrentModificationException(); |
767 |
< |
} |
768 |
< |
} |
769 |
< |
|
770 |
< |
private static class Entry { |
771 |
< |
Object element; |
772 |
< |
Entry next; |
773 |
< |
Entry previous; |
774 |
< |
|
775 |
< |
Entry(Object element, Entry next, Entry previous) { |
776 |
< |
this.element = element; |
777 |
< |
this.next = next; |
778 |
< |
this.previous = previous; |
779 |
< |
} |
780 |
< |
} |
781 |
< |
|
782 |
< |
private Entry addBefore(Object o, Entry e) { |
783 |
< |
Entry newEntry = new Entry(o, e, e.previous); |
784 |
< |
newEntry.previous.next = newEntry; |
785 |
< |
newEntry.next.previous = newEntry; |
786 |
< |
size++; |
787 |
< |
modCount++; |
788 |
< |
return newEntry; |
789 |
< |
} |
790 |
< |
|
791 |
< |
private void remove(Entry e) { |
792 |
< |
if (e == header) |
793 |
< |
throw new NoSuchElementException(); |
794 |
< |
|
795 |
< |
e.previous.next = e.next; |
796 |
< |
e.next.previous = e.previous; |
797 |
< |
size--; |
798 |
< |
modCount++; |
744 |
> |
nextIndex--; |
745 |
> |
lastReturned = header; |
746 |
> |
expectedModCount++; |
747 |
> |
} |
748 |
> |
|
749 |
> |
public void set(E e) { |
750 |
> |
if (lastReturned == header) |
751 |
> |
throw new IllegalStateException(); |
752 |
> |
checkForComodification(); |
753 |
> |
lastReturned.element = e; |
754 |
> |
} |
755 |
> |
|
756 |
> |
public void add(E e) { |
757 |
> |
checkForComodification(); |
758 |
> |
lastReturned = header; |
759 |
> |
addBefore(e, next); |
760 |
> |
nextIndex++; |
761 |
> |
expectedModCount++; |
762 |
> |
} |
763 |
> |
|
764 |
> |
final void checkForComodification() { |
765 |
> |
if (modCount != expectedModCount) |
766 |
> |
throw new ConcurrentModificationException(); |
767 |
> |
} |
768 |
> |
} |
769 |
> |
|
770 |
> |
private static class Entry<E> { |
771 |
> |
E element; |
772 |
> |
Entry<E> next; |
773 |
> |
Entry<E> previous; |
774 |
> |
|
775 |
> |
Entry(E element, Entry<E> next, Entry<E> previous) { |
776 |
> |
this.element = element; |
777 |
> |
this.next = next; |
778 |
> |
this.previous = previous; |
779 |
> |
} |
780 |
> |
} |
781 |
> |
|
782 |
> |
private Entry<E> addBefore(E e, Entry<E> entry) { |
783 |
> |
Entry<E> newEntry = new Entry<E>(e, entry, entry.previous); |
784 |
> |
newEntry.previous.next = newEntry; |
785 |
> |
newEntry.next.previous = newEntry; |
786 |
> |
size++; |
787 |
> |
modCount++; |
788 |
> |
return newEntry; |
789 |
> |
} |
790 |
> |
|
791 |
> |
private E remove(Entry<E> e) { |
792 |
> |
if (e == header) |
793 |
> |
throw new NoSuchElementException(); |
794 |
> |
|
795 |
> |
E result = e.element; |
796 |
> |
e.previous.next = e.next; |
797 |
> |
e.next.previous = e.previous; |
798 |
> |
e.next = e.previous = null; |
799 |
> |
e.element = null; |
800 |
> |
size--; |
801 |
> |
modCount++; |
802 |
> |
return result; |
803 |
|
} |
804 |
|
|
805 |
|
/** |
809 |
|
* @return a shallow copy of this <tt>LinkedList</tt> instance. |
810 |
|
*/ |
811 |
|
public Object clone() { |
812 |
< |
LinkedList clone = null; |
813 |
< |
try { |
814 |
< |
clone = (LinkedList)super.clone(); |
815 |
< |
} catch (CloneNotSupportedException e) { |
816 |
< |
throw new InternalError(); |
817 |
< |
} |
812 |
> |
LinkedList<E> clone = null; |
813 |
> |
try { |
814 |
> |
clone = (LinkedList<E>) super.clone(); |
815 |
> |
} catch (CloneNotSupportedException e) { |
816 |
> |
throw new InternalError(); |
817 |
> |
} |
818 |
|
|
819 |
|
// Put clone into "virgin" state |
820 |
< |
clone.header = new Entry(null, null, null); |
820 |
> |
clone.header = new Entry<E>(null, null, null); |
821 |
|
clone.header.next = clone.header.previous = clone.header; |
822 |
|
clone.size = 0; |
823 |
|
clone.modCount = 0; |
824 |
|
|
825 |
|
// Initialize clone with our elements |
826 |
< |
for (Entry e = header.next; e != header; e = e.next) |
826 |
> |
for (Entry<E> e = header.next; e != header; e = e.next) |
827 |
|
clone.add(e.element); |
828 |
|
|
829 |
|
return clone; |
834 |
|
* in the correct order. |
835 |
|
* |
836 |
|
* @return an array containing all of the elements in this list |
837 |
< |
* in the correct order. |
837 |
> |
* in the correct order. |
838 |
|
*/ |
839 |
|
public Object[] toArray() { |
840 |
< |
Object[] result = new Object[size]; |
840 |
> |
Object[] result = new Object[size]; |
841 |
|
int i = 0; |
842 |
< |
for (Entry e = header.next; e != header; e = e.next) |
842 |
> |
for (Entry<E> e = header.next; e != header; e = e.next) |
843 |
|
result[i++] = e.element; |
844 |
< |
return result; |
844 |
> |
return result; |
845 |
|
} |
846 |
|
|
847 |
|
/** |
859 |
|
* does not contain any null elements. |
860 |
|
* |
861 |
|
* @param a the array into which the elements of the list are to |
862 |
< |
* be stored, if it is big enough; otherwise, a new array of the |
863 |
< |
* same runtime type is allocated for this purpose. |
862 |
> |
* be stored, if it is big enough; otherwise, a new array of the |
863 |
> |
* same runtime type is allocated for this purpose. |
864 |
|
* @return an array containing the elements of the list. |
865 |
|
* @throws ArrayStoreException if the runtime type of a is not a |
866 |
|
* supertype of the runtime type of every element in this list. |
867 |
|
* @throws NullPointerException if the specified array is null. |
868 |
|
*/ |
869 |
< |
public Object[] toArray(Object a[]) { |
869 |
> |
public <T> T[] toArray(T[] a) { |
870 |
|
if (a.length < size) |
871 |
< |
a = (Object[])java.lang.reflect.Array.newInstance( |
871 |
> |
a = (T[])java.lang.reflect.Array.newInstance( |
872 |
|
a.getClass().getComponentType(), size); |
873 |
|
int i = 0; |
874 |
< |
for (Entry e = header.next; e != header; e = e.next) |
875 |
< |
a[i++] = e.element; |
874 |
> |
Object[] result = a; |
875 |
> |
for (Entry<E> e = header.next; e != header; e = e.next) |
876 |
> |
result[i++] = e.element; |
877 |
|
|
878 |
|
if (a.length > size) |
879 |
|
a[size] = null; |
888 |
|
* is, serialize it). |
889 |
|
* |
890 |
|
* @serialData The size of the list (the number of elements it |
891 |
< |
* contains) is emitted (int), followed by all of its |
892 |
< |
* elements (each an Object) in the proper order. |
891 |
> |
* contains) is emitted (int), followed by all of its |
892 |
> |
* elements (each an Object) in the proper order. |
893 |
|
*/ |
894 |
< |
private synchronized void writeObject(java.io.ObjectOutputStream s) |
894 |
> |
private void writeObject(java.io.ObjectOutputStream s) |
895 |
|
throws java.io.IOException { |
896 |
< |
// Write out any hidden serialization magic |
897 |
< |
s.defaultWriteObject(); |
896 |
> |
// Write out any hidden serialization magic |
897 |
> |
s.defaultWriteObject(); |
898 |
|
|
899 |
|
// Write out size |
900 |
|
s.writeInt(size); |
901 |
|
|
902 |
< |
// Write out all elements in the proper order. |
902 |
> |
// Write out all elements in the proper order. |
903 |
|
for (Entry e = header.next; e != header; e = e.next) |
904 |
|
s.writeObject(e.element); |
905 |
|
} |
908 |
|
* Reconstitute this <tt>LinkedList</tt> instance from a stream (that is |
909 |
|
* deserialize it). |
910 |
|
*/ |
911 |
< |
private synchronized void readObject(java.io.ObjectInputStream s) |
911 |
> |
private void readObject(java.io.ObjectInputStream s) |
912 |
|
throws java.io.IOException, ClassNotFoundException { |
913 |
< |
// Read in any hidden serialization magic |
914 |
< |
s.defaultReadObject(); |
913 |
> |
// Read in any hidden serialization magic |
914 |
> |
s.defaultReadObject(); |
915 |
|
|
916 |
|
// Read in size |
917 |
|
int size = s.readInt(); |
918 |
|
|
919 |
|
// Initialize header |
920 |
< |
header = new Entry(null, null, null); |
920 |
> |
header = new Entry<E>(null, null, null); |
921 |
|
header.next = header.previous = header; |
922 |
|
|
923 |
< |
// Read in all elements in the proper order. |
924 |
< |
for (int i=0; i<size; i++) |
925 |
< |
add(s.readObject()); |
708 |
< |
} |
709 |
< |
|
710 |
< |
public Object peek() { |
711 |
< |
if (size==0) |
712 |
< |
return null; |
713 |
< |
return getFirst(); |
714 |
< |
} |
715 |
< |
|
716 |
< |
public Object element() { |
717 |
< |
return getFirst(); |
923 |
> |
// Read in all elements in the proper order. |
924 |
> |
for (int i=0; i<size; i++) |
925 |
> |
addBefore((E)s.readObject(), header); |
926 |
|
} |
719 |
– |
|
720 |
– |
public Object poll() { |
721 |
– |
if (size==0) |
722 |
– |
return null; |
723 |
– |
return removeFirst(); |
724 |
– |
} |
725 |
– |
|
726 |
– |
public Object remove() { |
727 |
– |
return removeFirst(); |
728 |
– |
} |
729 |
– |
|
730 |
– |
public boolean offer(Object x) { |
731 |
– |
return add(x); |
732 |
– |
} |
733 |
– |
|
927 |
|
} |