double linked list in Java (Java)

A doubly linked list is a list that contains links to next and previous nodes. Unlike singly linked lists where traversal is only one way, doubly linked lists allow traversals in both ways.

Source code
import java.util.NoSuchElementException;

public class DoublyLinkedListImpl<E> {

    private Node head;
    private Node tail;
    private int size;
   
    public DoublyLinkedListImpl() {
        size = 0;
    }
    /**
     * this class keeps track of each element information
     * @author java2novice
     *
     */
    private class Node {
        E element;
        Node next;
        Node prev;

        public Node(E element, Node next, Node prev) {
            this.element = element;
            this.next = next;
            this.prev = prev;
        }
    }
    /**
     * returns the size of the linked list
     * @return
     */
    public int size() { return size; }
   
    /**
     * return whether the list is empty or not
     * @return
     */
    public boolean isEmpty() { return size == 0; }
   
    /**
     * adds element at the starting of the linked list
     * @param element
     */
    public void addFirst(E element) {
        Node tmp = new Node(element, head, null);
        if(head != null ) {head.prev = tmp;}
        head = tmp;
        if(tail == null) { tail = tmp;}
        size++;
        System.out.println("adding: "+element);
    }
   
    /**
     * adds element at the end of the linked list
     * @param element
     */
    public void addLast(E element) {
       
        Node tmp = new Node(element, null, tail);
        if(tail != null) {tail.next = tmp;}
        tail = tmp;
        if(head == null) { head = tmp;}
        size++;
        System.out.println("adding: "+element);
    }
   
    /**
     * this method walks forward through the linked list
     */
    public void iterateForward(){
       
        System.out.println("iterating forward..");
        Node tmp = head;
        while(tmp != null){
            System.out.println(tmp.element);
            tmp = tmp.next;
        }
    }
   
    /**
     * this method walks backward through the linked list
     */
    public void iterateBackward(){
       
        System.out.println("iterating backword..");
        Node tmp = tail;
        while(tmp != null){
            System.out.println(tmp.element);
            tmp = tmp.prev;
        }
    }
   
    /**
     * this method removes element from the start of the linked list
     * @return
     */
    public E removeFirst() {
        if (size == 0) throw new NoSuchElementException();
        Node tmp = head;
        head = head.next;
        head.prev = null;
        size--;
        System.out.println("deleted: "+tmp.element);
        return tmp.element;
    }
   
    /**
     * this method removes element from the end of the linked list
     * @return
     */
    public E removeLast() {
        if (size == 0) throw new NoSuchElementException();
        Node tmp = tail;
        tail = tail.prev;
        tail.next = null;
        size--;
        System.out.println("deleted: "+tmp.element);
        return tmp.element;
    }
   
    public static void main(String a[]){
       
        DoublyLinkedListImpl<Integer> dll = new DoublyLinkedListImpl<Integer>();
     
        dll.addFirst(10);
        dll.addFirst(34);
        dll.addLast(56);
        dll.addLast(364);
        dll.iterateForward();
        dll.removeFirst();
        dll.removeLast();
        dll.iterateBackward();
    }
}