What is the time complexity of LinkedList.getLast() in Java?

Question

I have a private LinkedList in a Java class & will frequently need to retrieve the last element in the list. The lists need to scale, so I\'m trying to decide whether I

Answer 1

From the Java 6 source code:

* @author  Josh Bloch
 * @version 1.67, 04/21/06
 * @see     List
 * @see     ArrayList
 * @see     Vector
 * @since 1.2
 * @param  the type of elements held in this collection
 */

public class LinkedList
    extends AbstractSequentialList
    implements List, Deque, Cloneable, java.io.Serializable
{
    private transient Entry header = new Entry(null, null, null);
    private transient int size = 0;

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

...

    /**
     * Returns the first element in this list.
     *
     * @return the first element in this list
     * @throws NoSuchElementException if this list is empty
     */
    public E getFirst() {
    if (size==0)
        throw new NoSuchElementException();

    return header.next.element;
    }

    /**
     * Returns the last element in this list.
     *
     * @return the last element in this list
     * @throws NoSuchElementException if this list is empty
     */
    public E getLast()  {
    if (size==0)
        throw new NoSuchElementException();

    return header.previous.element;
    }

...

}

so that's O(1) for both getFirst() & getLast()