LinkedList

LinkedList

一、总结

1.基于 jdk 1.8 源码分析

2.

二、类声明

/**
 * Linked list implementation of the <tt>List</tt> interface.  Implements all
 * optional list operations, and permits all elements (including
 * <tt>null</tt>).  In addition to implementing the <tt>List</tt> interface,
 * the <tt>LinkedList</tt> class provides uniformly named methods to
 * <tt>get</tt>, <tt>remove</tt> and <tt>insert</tt> an element at the
 * beginning and end of the list.  These operations allow linked lists to be
 * used as a stack, {@linkplain Queue queue}, or {@linkplain Deque
 * double-ended queue}. <p>
 * 允许所有元素均为 null 
 *
 *
 * The class implements the <tt>Deque</tt> interface, providing
 * first-in-first-out queue operations for <tt>add</tt>,
 * <tt>poll</tt>, along with other stack and deque operations.<p>
 * 实现Deque接口，添加元素时如同 先进先出 的队列
 * 
 * All of the operations perform as could be expected for a doubly-linked
 * list.  Operations that index into the list will traverse the list from
 * the beginning or the end, whichever is closer to the specified index.<p>
 *
 * <p><strong>Note that this implementation is not synchronized.</strong>
 * If multiple threads access a linked list concurrently, and at least
 * one of the threads modifies the list structurally, it <i>must</i> be
 * synchronized externally.  (A structural modification is any operation
 * that adds or deletes one or more elements; merely setting the value of
 * an element is not a structural modification.)  This is typically
 * accomplished by synchronizing on some object that naturally
 * encapsulates the list.
 * 非线程安全的实现
 * If no such object exists, the list should be "wrapped" using the
 * {@link Collections#synchronizedList Collections.synchronizedList}
 * method.  This is best done at creation time, to prevent accidental
 * unsynchronized access to the list:<pre>
 *   List list = Collections.synchronizedList(new LinkedList(...));</pre>
 * 
 * <p>The iterators returned by this class's <tt>iterator</tt> and
 * <tt>listIterator</tt> methods are <i>fail-fast</i>: if the list is
 * structurally modified at any time after the iterator is created, in
 * any way except through the Iterator's own <tt>remove</tt> or
 * <tt>add</tt> methods, the iterator will throw a {@link
 * ConcurrentModificationException}.  Thus, in the face of concurrent
 * modification, the iterator fails quickly and cleanly, rather than
 * risking arbitrary, non-deterministic behavior at an undetermined
 * time in the future.
 *
 * <p>Note that the fail-fast behavior of an iterator cannot be guaranteed
 * as it is, generally speaking, impossible to make any hard guarantees in the
 * presence of unsynchronized concurrent modification.  Fail-fast iterators
 * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
 * Therefore, it would be wrong to write a program that depended on this
 * exception for its correctness:   <i>the fail-fast behavior of iterators
 * should be used only to detect bugs.</i>
 *
 * <p>This class is a member of the
 * <a href="{@docRoot}/../technotes/guides/collections/index.html">
 * Java Collections Framework</a>.
 *
 * @author  Josh Bloch
 * @version 1.67, 04/21/06
 * @see	    List
 * @see	    ArrayList
 * @see	    Vector
 * @since 1.2
 * @param <E> the type of elements held in this collection
 */

public class LinkedList<E>
    extends AbstractSequentialList<E>
    implements List<E>, Deque<E>, Cloneable, java.io.Serializable

1.继承 AbstractSequentialList

2.实现 Deque

二、成员变量及构造方法

    // 
    private transient Entry<E> header = new Entry<E>(null, null, null);
    private transient int size = 0;

    /**
     * Constructs an empty list.
     */
    public LinkedList() {
        header.next = header.previous = header;
    }

    /**
     * Constructs a list containing the elements of the specified
     * collection, in the order they are returned by the collection's
     * iterator.
     *
     * @param  c the collection whose elements are to be placed into this list
     * @throws NullPointerException if the specified collection is null
     */
    public LinkedList(Collection<? extends E> c) {
	this();
	addAll(c);
    }

博文参考：
http://www.cnblogs.com/ITtangtang/p/3948610.html