简单的链表实现

Java LinkedList底层是基于双向链表来实现的，为了更好的理解其实现原理，自己对简单的链表结构做了Java实现，代码如下

class MyLinkedList<E>{
private int size = 0;
private Node<E> head;
private Node<E> last;
private Node<E> first;

public MyLinkedList() {
    this.size = 0;
    this.last = null;
    this.first = null;
    head = first;
}

public boolean add(E e){
    linkLast(e);
    return true;
}

public void reset(){
    head = first;
}

public boolean hasNext(){
    return head != last.next;
}

public E next(){
    Node<E> temp = head;
    head = temp.next;
    return temp.item;
}

private void linkLast(E e) {
    Node<E> la = last;
    Node<E> newNode = new Node<E>(e, la, null);
    last = newNode;
    if (la == null){
        head = newNode;
        first = newNode;
    } else {
        la.next = newNode;
    }
    size++;
}

class Node<E>{
    E item;
    Node<E> pre;
    Node<E> next;

    public Node(E item, Node<E> pre, Node<E> next) {
        this.item = item;
        this.pre = pre;
        this.next = next;
    }
}
}