java建立双向链表，插入结点，删除节点

//双向链表的结构
class DbList {
	DbList prior;
	DbList next;
	String data;
}
/**
 * 双向链表
 * 
 */
public class BuildDbLinkList {
	public static void dbList(DbList head) {
		String s;
		DbList first = head;
		Scanner scanner = new Scanner(System.in);
		while (true) {
			s = scanner.next();
			// 输入#结束输入,将链表尾指针指向表头，同时使表头priori指针指向尾指针，构成双向循环链表 
			if (s.equals("#")) {
				first.next = head;
				head.prior = first;
				break;
			}
			DbList node = new DbList();
			node.data = s;
			// 前一个结点的后指向指针指向当前结点
			first.next = node;
			// 当前结点的前指针指向前一个结点
			node.prior = first;
			node.next = null;
			first = first.next;
		}
	}

	// 在双向链表的第i个位置插入元素str
	public static void insertDbList(DbList head, int i, String str) {
		int j = 1;
		DbList cur = head.next;
		// 移动到第i个位置
		while (cur != null && j < i) {
			cur = cur.next;
			j++;
		}
		if (cur == null || j > i) {
			return;
		}
		DbList node = new DbList();
		node.data = str;
		node.prior = cur.prior;
		cur.prior.next = node;
		node.next = cur;
		cur.prior = node;
	}

	// 删除双向链表的第i个位置的结点
	public static void deleteDbList(DbList head, int i) {
		int j = 1;
		DbList cur = head.next;
		// 移动到第i个位置
		while (cur != null && j < i) {
			cur = cur.next;
			j++;
		}
		if (cur == null || j > i) {
			return;
		}
		cur.prior.next = cur.next;
		cur.next.prior = cur.prior;
	}

	public static void main(String[] args) {
		DbList head = new DbList();
		dbList(head);
		DbList current = head.next;
		while (current !=null && current != head) {
			System.out.println(current.data);
			current = current.next;
		}
	}
}