如何更新.txt文件java中的包含

Question

例如，我有一个名为的文件file.txt，其中包含个人信息（身份证，姓名，薪水）：

A123 Anna 3000
A234 Alex 4000
A986 Jame 5000

如何编写允许用户输入人的ID并补充薪水的Java代码？最终输出将如下所示：

输入ID：A123

输入补充工资：2000

运行程序后的file.txt：

A123 Anna 5000
A234 Alex 4000
A986 Jame 5000

这是我到目前为止所做的，但没有成功：

public static void addDalary() throws IOException {
        String ID, Nanme;
        double salary;


            Scanner console = new Scanner(System.in);
            System.out.print("Enter ID : ");
            String pID = console.nextLine();
            System.out.print("Enter replenish salary: ");
            replenish = console.nextInt();

            Scanner input = new Scanner(new File("file.txt"));
            while (input.hasNext()) {
                ID = input.next();
                Name = input.next();
                salary = input.nextDouble();

                if (ID == pID) {    
                    salary = salary + replenish;
                }
            }
            input.close();
        }

我刚接触这些东西。任何帮助将不胜感激。

Answer 1

您必须使用从原始文件逐行读取它的方法。搜索并用新号码替换薪水。将内容写入新的临时文件。删除原始文件。最后将临时文件替换为原始文件名。这是执行此操作的代码：

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Scanner;

public class FileContentUpdater {

    public static void main(String args[]) throws IOException {
        String ID, Name;
        double salary;
        int replenish;

        Scanner console = new Scanner(System.in);
        System.out.print("Enter ID : ");
        String pID = console.nextLine();
        System.out.print("Enter replenish salary: ");
        replenish = console.nextInt();

        File originalFile = new File("file.txt");
        BufferedReader br = new BufferedReader(new FileReader(originalFile));

        // Construct the new file that will later be renamed to the original
        // filename.
        File tempFile = new File("tempfile.txt");
        PrintWriter pw = new PrintWriter(new FileWriter(tempFile));

        String line = null;
        // Read from the original file and write to the new
        // unless content matches data to be removed.
        while ((line = br.readLine()) != null) {

            if (line.contains(pID)) {
                String strCurrentSalary = line.substring(line.lastIndexOf(" "), line.length());
                if (strCurrentSalary != null || !strCurrentSalary.trim().isEmpty()) {
                    int replenishedSalary = Integer.parseInt(strCurrentSalary.trim()) + replenish;
                    System.out.println("replenishedSalary : " + replenishedSalary);
                    line = line.substring(0,line.lastIndexOf(" ")) + replenishedSalary;
                }

            }
            pw.println(line);
            pw.flush();
        }
        pw.close();
        br.close();

        // Delete the original file
        if (!originalFile.delete()) {
            System.out.println("Could not delete file");
            return;
        }

        // Rename the new file to the filename the original file had.
        if (!tempFile.renameTo(originalFile))
            System.out.println("Could not rename file");

    }
}