LinkedList是双向链表不是双向循环链表

[nvkwo3314200]

jdk1.8中
/** * Links e as last element. */ void linkLast(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++; }
newNode的next并没有指向first而是null

LinkBefore方法中还用pred == null来判断是否插入到第一个node
/** * Inserts element e before non-null Node succ. */ void linkBefore(E e, Node<E> succ) { // assert succ != null; final Node<E> pred = succ.prev; final Node<E> newNode = new Node<>(pred, e, succ); succ.prev = newNode; if (pred == null) first = newNode; else pred.next = newNode; size++; modCount++; }
所以没看出来循环

[freestylefly]

是@

[Snailclimb]

之前没有分清双向链表和双向循环链表 感谢您提出来！