java - java中链表的实现

Question

我正在阅读有关java中的链表的内容，我确实编写了这段代码，当我运行它时，我得到3作为输出，它应该打印出插入数字的相反顺序，如下所示:10 7 3 ..我的代码有什么问题？

public class List {
    private class ListNode {
        private int contents;
        private ListNode next;

        ListNode(int contents) {
            this.contents = contents;
            this.next = null;
        }
    }

    private ListNode head;

    public List() {
        head = null;
    }

    public void insert(int contents) {

        ListNode newNode = new ListNode(contents);
        if (head == null) {
            head = newNode;
        }

        ListNode current = head;
        while (current != null) {
            current = current.next;
        }

        current = newNode;

    }

    public void reverse() {

        ListNode current = head;
        ListNode nodeNext = current.next;

        while (nodeNext != null) {
            current.next = null;
            nodeNext.next = current;
            current = nodeNext;
        }

        head = current;
    }

    public String toString() {

        String s = "";
        ListNode current = head;
        while (current != null) {
            s = current.contents + s;
            current = current.next;
        }

        return s;
    }

    public static void main(String[] args) {

        List l = new List();
        l.insert(3);
        l.insert(7);
        l.insert(10);
        l.reverse();
        System.out.println(l.toString());

    }
}

谢谢

Answer 1

您的 insert 方法不会将新节点连接到现有列表的最后一个节点。您必须将新节点分配给现有列表最后一个节点的 node.next :

public void insert(int contents) {

    ListNode newNode = new ListNode(contents);
    if (head == null) {
        head = newNode;
        return;
    }

    ListNode current = head;
    while (current.next != null) {
        current = current.next;
    }

    current.next = newNode;

}