Java 如何从文件中读取并将内容保存到链表中？

How to read from a file and save the content into a linked list?

提问by user2252700

I'm trying to write the code for a program that saves the content of a txt file into a singly linked list, every line in the txt file represent an object. I used Scanner to read from the file but I don't know how to get the words in the list.

我正在尝试为一个程序编写代码，该程序将 txt 文件的内容保存到一个单向链表中，txt 文件中的每一行都代表一个对象。我使用 Scanner 从文件中读取，但我不知道如何获取列表中的单词。

any tip or hint is highly appreciated.

任何提示或提示都非常感谢。

my attempt:

我的尝试：

class Item

类项目

public class Item implements Serializable {
private String name;
private double price;

public Item() {
name="" ; 
price=0.00 ;
}

public Item(String n, double p) {
name = n ; 
price = p ;
}

public void setName(String n) {
name = n ;
}

public void setPrice(double p) { price = p ;
}

public String getName() { 
return name ; 
}

public double getPrice() {
return price ;
}
}

class Node

类节点

public class Node {
public Item data ;
public Node next ;

public Node(Item d) {
    data = d ;
}

public Node(Item d, Node n) {
    data = d ; 
    next = n ; 
}

public String toString() {
    return data+"";
}
}

class ListItems

类 ListItems

public class ListItems {

private Node first;

public ListItems(){
    first=null;
}

public boolean isEmpty(){
    return first==null;
}

public void addAnItems(Item d, int i){
    Node node1=new Node(d);
    node1.next=first;
    first=items.get(i);
}

public void displayList(){
    Node current = first;

        while(current != null){
        System.out.println(current.toString());
        current=current.next;
        }
}
}

class FileItems

类文件项

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

public class FileItems {
public static void main (String[]args){
Scanner input1=new Scanner(System.in) ;
        try {
        Scanner input2=new Scanner(new File("items.txt")) ;
        }

        catch (FileNotFoundException e) {
        System.out.println("ERROR OPENING FILE") ;
        System.Exit(1) ;
        }

        while (input2.hasNext()){
        String name1=input2.next() ;
        double price1=input2.nextDouble() ;
        }

            ListItems items=new ListItems();
                System.out.println("CHOOSE ONE OF THE FOLLOWING OPTIONS :") ;
                System.out.println("ENTER 1 TO ADD AN ITEM TO THE LIST") ;
                System.out.println("ENTER 2 TO DELETE AN ITEM FROM THE LIST") ;
                System.out.println("ENTER 3 TO DISPLAY ALL THE ITEMS IN THE LIST") ;
                System.out.println("ENTER 4 TO CLOSE THE PROGRAM") ;

                int in=input1.nextInt() ;

                        switch (in) {
                        case 1 : case1() ; 
                            break ;
                        case 2 : case1() ;
                            break ;
                        case 3 : displayList() ;
                            break ;
                        case 4 : System.Exit(1) ;
                            break ;
                        }

                        public void case1() {
                            System.out.println("ENTER THE NAME OF THE ITEM, THE PRICE AND THE INDEX ");

                            try {
                            System.out.println("NAME: ") ; 
                                String n2=input1.next() ; 
                            System.out.println("PRICE: ") ;
                                double p2=input1.nextDouble() ;
                            System.out.println("INDEX: ") ; 
                                int index=input1.nextInt() ;
                            }

                            catch (InputMismatchException e) {
                            System.out.print("INVALID INPUT") ;
                            }

                        Item I=new Item(n2, p2) ;
                        addAnItem(I, index) ;
                        }

                        public static case2() {
                            System.out.println("ENTER THE INDEX OF THE ITEM TO DELETE IT ") ;

                            try {
                            int index=input1.nextInt() ;
                            }

                            catch (InputMismatchException e) {
                            System.out.print("INVALID INPUT") ;
                            }
                        items.remove(index) ;
                        }
        }
        }

采纳答案by Mavrick

Open the text file and read each line as a String and place that String object into a LinkedList. Print all of the lines in the LinkedList in reverse order.

打开文本文件并将每一行作为一个字符串读取，然后将该字符串对象放入一个 LinkedList。以相反的顺序打印 LinkedList 中的所有行。

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

public class FileLinkList
{
public static void main(String args[])throws IOException{
String content = new String();
int count=1;
File file = new File("abc.txt");
LinkedList<String> list = new LinkedList<String>();

 try {
Scanner sc = new Scanner(new FileInputStream(file));
while (sc.hasNextLine()){
content = sc.nextLine();
list.add(content);
}
sc.close();
}catch(FileNotFoundException fnf){
fnf.printStackTrace();
}
catch (Exception e) {
e.printStackTrace();
System.out.println("\nProgram terminated Safely...");
}

Collections.reverse(list);
Iterator i = list.iterator();
while (i.hasNext()) {
System.out.print("Node " + (count++) + " : ");
System.out.println(i.next());
}
 }
 }