以逗号分隔的文件内容

Question

如果内容相同，我想将两个文件合并为一个：

first.txt

second.txt

后果txt

首先，我想读取文件的内容并将其保存到数组中。但是怎么做呢？

import java.io.FileNotFoundException;
import java.util.Scanner;
import java.io.FileReader;  

public class FileIO {
    

    public static void main(String[] args) throws FileNotFoundException {
        Scanner sc = new Scanner(new FileReader("first.txt"));
        
        StringBuilder sb = new StringBuilder();
        while(sc.hasNext()) {
            sb.append(sc.next());
        }
        sc.close();
        String outString = sb.toString();
        
        System.out.println(outString);
    }

}

输出： 1,2,3

例如，如何将逗号分隔开来，以便我可以编写a[0]=1？

Answer 1

import java.io.FileNotFoundException;
import java.util.Scanner;
import java.io.FileReader;  

public class FileIO {
    

    public static void main(String[] args) throws FileNotFoundException {
        Scanner sc = new Scanner(new FileReader("first.txt"));
        
        List<String> res1 = new ArrayList<>();
        while(sc.hasNext()) {
            res1.add(sc.next());
        }
        sc.close();
        System.out.println(res1);
    }

}

有关如何在两个列表中获得相似元素，请查看https://docs.oracle.com/javase/8/docs/api/java/util/Collection.html#retainAll-爪哇。util。收藏-

Answer 2

读取文件的每一行，然后通过，分隔符拆分（）每行的内容。像这样：

public static void main(String[] args) throws FileNotFoundException 
{
    Scanner sc = new Scanner(new FileReader("first.txt"));
    
    StringBuilder joinedString = new StringBuilder(); // To join each line together
    
    
    while(sc.hasNextLine()) 
    {
        joinedString.append(sc.nextLine()); // appending each line to a big string
    }
    sc.close();
    
    String[] individualNumbers = joinedString.toString().split(","); // splitting through ","
    System.out.println(individualNumbers[0]);
}

这会打印出你的第一个号码。所有数字都作为字符串数组中的字符串。