采用快慢针的方法，ListNode p指向链表头部，ListNode q = p.next。再定义一个ListNode start表示删除指定val值后的头结点，先赋值为p。结点的遍历从q结点开始，当q.val不等于val时，p的下一个结点指向q，并且p、q同时向后移动，直至q=null，表示遍历链表结束，此时p.next = null。因为一开始我们是从第二个结点开始遍历链表的，所以最后我们要对start结点进行判断start.val是否和val相等，如果相等那么返回start.next，否则返回start

public class RemoveElements {    public static void main(String[] args) {        ListNode one = new ListNode(1);        ListNode two = new ListNode(1);//        ListNode three = new ListNode(6);//        ListNode four = new ListNode(3);//        ListNode five = new ListNode(4);//        ListNode six = new ListNode(5);//        ListNode seven = new ListNode(6);        one.next = two;        two.next = null;//        three.next = four;//        four.next = five;//        five.next = six;//        six.next = seven;//        seven.next = null;        ListNode listNode = removeElements(one, 1);        printLink(listNode);    }    public static void printLink(ListNode head) {        if (null == head) System.out.println("head is null");        while (head != null) {            System.out.println(head.val);            head = head.next;        }    }    public static ListNode removeElements(ListNode head, int val) {        if (null == head) return head;        ListNode p = head, q = p.next, start = p;        while (q != null) {            if (q.val != val) {                p.next = q;                p = p.next;            }            q = q.next;        }        p.next = null;        if (start.val == val) return start.next;        return start;    }}复制代码