建一个链表

//单独的一个类
public class LinkNode{
    int val;
    LinkNode next;

    LinkNode(int x){
        val = x;
    }
}   

=================================

//主函数方法
public static void main(String[] args) {
        LinkNode head = new LinkNode(-1);
        LinkNode firstNode = new LinkNode(0);
        LinkNode secondNode = new LinkNode(1);
        LinkNode thirdNode = new LinkNode(2);

        head.val = 1;
        head.next = firstNode;
        firstNode.next = secondNode;
        secondNode.next = thirdNode;

        a(head);

}

private static void a(LinkNode linkNode) {
        System.out.println("second的值是：" + linkNode.next.next.val);
}

最后输出

second的值是：1