Question

我正在尝试编写一个程序来反转给定的链表。首先，我将从用户那里读取数字并将其传递给将数字转换为LinkedList的函数，然后将链表传递给帮助函数，该函数将反转给定的LinkedList。

这是我的程序：

import java.io.*;
import java.util.*;


public class Solution {

    public class Link {
        Node head;

        public class Node {
            int data;
            Node next;
            Node(int x) {
                data = x;
                next = null;
            } 
        } // End of class Node

        public void printList() { 
            Node n = head; 
            while (n != null) { 
                System.out.print(n.data+" "); 
                n = n.next; 
            } 
        } 

        public void createList(String num) {
            this.head = new Node(num.charAt(0));
            Node prev = head ;
            for(int i = 1; i < num.length(); i++) {
                Node newNode = new Node(num.charAt(i));
                prev.next =  newNode;
                prev =  newNode;
            }
        }
    } // end of class Link

    public Node reverse(Node curr) {
        if (curr == null) return null;
        if(curr.next != null) {
            Node forward = reverse(curr->next);
            curr.next.next = curr ;
            curr.next = null;   
        } else {
            return res;
        }
        return forward;
    }    

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String number1 = sc.next();
        // System.out.println(number1);

        String number2 = sc.next();
        //System.out.println(number2);

        Link first = new Link();
        first.createList(number1);
        first.printList();

        System.out.println("''''''''''");
        Link second = new Link();
        second.createList(number1);
        second.printList();
        System.out.println("''''''''''");

        first.head = reverse(head); 
        first.printList();
        System.out.println("''''''''''");

        second.head = reverse(head);
        second.printList();
        System.out.println("''''''''''");
    }
}

这是我得到的错误：

Solution.java:47: error: cannot find symbol
  public Node reverse(Node curr)
                      ^
  symbol:   class Node
  location: class Solution
Solution.java:47: error: cannot find symbol
  public Node reverse(Node curr)
         ^
  symbol:   class Node
  location: class Solution
2 errors

我的问题是，即使Link类和Node类都是公共的，为什么反向方法不能访问符号Node？以及应该如何编写Java中的辅助方法，以便它们访问任何类的对象。

Answer 1

问题是您的类是内部类，而内部类的实例只能与外部类的实例一起使用。如果您将类设置为顶级，这是一个可能的解决方案，事情应该没事（您还必须修复反向方法）

class Node {
    int data;
    Node next;

    Node(int x) {
        data = x;
        next = null;
    }
}

class Link {

    Node head;

    public void printList() {
        Node n = head;
        while (n != null) {
            System.out.print(n.data + " ");
            n = n.next;
        }
    }

    public void createList(String num) {

        this.head = new Node(num.charAt(0));
        Node prev = head;
        for (int i = 1; i < num.length(); i++) {
            Node newNode = new Node(num.charAt(i));
            prev.next = newNode;
            prev = newNode;
        }
    }
}

public class Solution {

    public Node reverse(Node curr) {
        // to be implemented
        return null;
    }
}

将对象传递给Java中的辅助方法

1 个答案: