java--删除链表偶数节点

public class ListNode {
    int data;//当前节点的值
    ListNode next = null;//是指向下一个节点的指针/引用
    public ListNode(int data){
        this.data = data;
    }
}

public class DeleteListNode {
    public static ListNode delete(ListNode head){
        //链表为空
        if(head == null){
            return null;
        }
        ListNode odd = head;
        //链表长度为偶数
        if(length(head)%2 == 0){
            while (odd.next != null && odd.next.next != null){

                odd.next = odd.next.next;
                odd = odd.next;
                if(odd.next.next == null && odd.next != null){
                odd.next=null;
                }
            }
        }
        //链表长度为奇数
        if(length(head)%2 == 1){
            while (odd.next != null && odd.next.next != null){
                odd.next = odd.next.next;
                odd = odd.next;
            }
        }
        //返回头结点
        return head;

    }

    //返回链表长度
    private static int length(ListNode node){

        int length = 0;
        while (node != null){
            node = node.next;
            length++;
        }
        return length;
    }
    //打印链表
    private static void print(ListNode node) {
        System.out.print(node.data);
        if (node.next != null){
            print(node.next);
        }
    }

    public static void main(String[] args){
        ListNode node1 = new ListNode(1);
        ListNode node2 = new ListNode(2);
        ListNode node3 = new ListNode(3);
        ListNode node4 = new ListNode(4);
        ListNode node5 = new ListNode(5);
        ListNode node6 = new ListNode(6);
        ListNode node7 = new ListNode(7);
        ListNode node8 = new ListNode(8);
        ListNode node9 = new ListNode(9);
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;
        node5.next = node6;
        node6.next = node7;
        node7.next = node8;
        node8.next = node9;
        System.out.println("删除偶数节点前，链表为：");
        print(node1);
        delete(node1);
        System.out.println("\n删除偶数节点后，链表为：");
        print(node1);
    }

}