LinkedList如何在java项目中运用

public class LinkedList<E> implements List<E>, Deque<E> {  Node<E> first;  Node<E> last;  int size;   public boolean add(E e) {     final Node<E> l = last;     final Node<E> newNode = new Node<>(l, e, null);     last = newNode;     if (l == null)       first = newNode;     else       l.next = newNode;     size++;     modCount++;     return true;   }   private static class Node<E> {     E item;     Node<E> next;     Node<E> prev;      Node(Node<E> prev, E element, Node<E> next) {       this.item = element;       this.next = next;       this.prev = prev;     }   }  }