OO DoublyLinkedList

DoublyLinkedList.java

import java.util.Iterator;

import lombok.AllArgsConstructor;
import lombok.ToString;
import lombok.val;

@ToString
public class DoublyLinkedList<T> {

	private Node<T> first;
	private Node<T> last;

	public DoublyLinkedList() {
	}

	public void add(T item) {
		if (this.first == null) {
			this.first = this.last = new Node<>(null, item, null);
			return;
		}
		val created = new Node<>(this.last, item, null);
		this.last.next = created;
		this.last = created;
	}

	public boolean isEmpty() {
		return this.first == null;
	}

	@AllArgsConstructor
	@ToString(of = "content")
	private static class Node<T> {
		private Node<T> previous;
		private final T content;
		private Node<T> next;
	}

	@AllArgsConstructor
	public static class NormalIteration<T> implements Iterable<T> {
		private final DoublyLinkedList<T> list;

		@Override
		public Iterator<T> iterator() {
			return new DoublyLinkedListIterator<>(this.list, false);
		}
	}

	@AllArgsConstructor
	public static class ReversedIteration<T> implements Iterable<T> {
		private final DoublyLinkedList<T> list;

		@Override
		public Iterator<T> iterator() {
			return new DoublyLinkedListIterator<>(this.list, true);
		}
	}

	private static class DoublyLinkedListIterator<T> implements Iterator<T> {

		DoublyLinkedList<T> list;
		Node<T> last;
		boolean reversed;

		public DoublyLinkedListIterator(DoublyLinkedList<T> list, boolean reversed) {
			super();
			this.list = list;
			this.reversed = reversed;
			this.last = this.reversed ? this.list.last : this.list.first;
		}

		@Override
		public boolean hasNext() {
			return !this.list.isEmpty() && this.last != null;
		}

		@Override
		public T next() {
			val next = this.last.content;
			this.last = reversed ? this.last.previous : this.last.next;
			return next;
		}

	}

	public static void main(String[] args) {

		val list = new DoublyLinkedList<Integer>();

		list.add(1);
		list.add(2);
		list.add(3);

		for (val item : new NormalIteration<>(list))
			System.out.println(item);

		System.out.println();

		for (val item : new ReversedIteration<>(list))
			System.out.println(item);

	}

}