从文本文件中读取，并将其放入链表中

Question

null

>

构造函数，它接受两个输入:(String，String)。这两个输入以正确的顺序表示lastname和firstname。构造函数只需将参数中的数据分配给实例变量。

名为toString（）的公共实例方法，它返回一个字符串数据（学生的姓名），格式为“lastname,firstname”。

类MainApp

null

Ang
Bryan
Santos
Charlie
Chua
Leah
Yee
John
Abas
Ryan
Tulfo
Ram
Ching
Daryl
Tulfo
Dona
Ching
Daniela`

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

public class MainApp {
    static class Node{
        Student info;
        Node next;
        public Node(Student info){
            this.info = info;
            next = null;
        }
        public Node(Student info, Node node){
            this.info = info;
            next = node;
        }
        
    }
    static class StudentLinkedList{
        Node head, tail;
        
        public StudentLinkedList(){
            head = tail = null;
        }
        public void addToTail(Node node){
            if(head == null){
                head = tail = null;
                return;
            }
            tail.next = node;
            tail = node;
        }
        
        public void addToHead(Node node){
            if(head == null){
                head = tail = null;
                return;
            }
            node.next =head;
            head = node;
        }
        
        public void printAll(){
            Node temp = head;
            while(temp != null){
                temp.info.toString();
                temp = temp.next;
            }
        }
    }
    
    
    public static void main (String args[])throws FileNotFoundException {
        Scanner in = new Scanner(new FileReader("students.txt"));
        StudentLinkedList list = new    StudentLinkedList();
        
        String ln, fn;
        Student s;
        Node node;
          while (in.hasNext()) {
              ln =  in.nextLine();
              fn = in.nextLine();
              
              s = new Student(ln,fn);
              node = new Node(s);
          }
          if(in.hasNext())
                in.nextLine();
          in.close(); 
    
    }
   
    
}

public class Student {
    
    private String lastname, firstname;
    
    public Student(String ln, String fn) {
        this.lastname = ln;
        this.firstname = fn;
            
    }
    public void setLastName(String lastname){
        this.lastname = lastname;
    }
    public void setFirstName(String firstname){
        this.firstname = firstname;
    }
    public String getLastName(){
        return lastname;
    }
    public String getFirstName(){
        return firstname;
    }
    @Override
    public  String  toString(){
        String str = (lastname +", "+ firstname);
        return str;
    }        
    
}

Answer 1

加法必须做什么？

>

当尾部==null（和头部==null）时

head = newNode
tail = newNode

当tail！=null（和head！=null）

tail.next = newNode
tail = newNode