java - 列出文件夹中的所有 txt 文件，并在所有 txt 文件中的一行添加字符串

Question

我正在尝试列出目录中的所有txt文件，逐个读取txt文件并在同一txt文件中编辑一行。继续对所有其他 txt 文件执行相同操作。当我尝试以下代码时，我的 txt 文件变为空白。请帮忙。

import java.io.File;
import java.util.ArrayList;
import java.io.*;

public class MainClass {

    public static void main(String[] args) throws IOException {
        String s = null;
        ArrayList<String> lines = new ArrayList<String>();
        String dir = "C:\\Users\\ME\\Desktop\\XX";
        String line = null;
        File folder = new File(dir);
        String[] files = folder.list();
        for (String file : files) {
            try {
                File f = new File(dir + "\\" + file);
                if (file.endsWith(".ind")) {
                    FileReader fileReader = new FileReader(f);
                    // Always wrap FileReader in BufferedReader.
                    BufferedReader bufferedReader = new BufferedReader(fileReader);
                    line = bufferedReader.readLine();
                    while ((bufferedReader.readLine()) != null) {
                        if (line.contains("GROUP_FILENAME:"))
                            s = line.substring(0, 15) + "/HOME/FOLDER/" + line.substring(15);
                        lines.add(s);
                        System.out.println(s);
                    }
                    fileReader.close();
                    bufferedReader.close();
                    FileWriter fw = new FileWriter(f);
                    BufferedWriter out = new BufferedWriter(fw);
                    for (String st : lines)
                        out.write(st);
                    out.flush();
                    out.close();

                }
            } catch (FileNotFoundException ex) {
                System.out.println("Unable to open file '" + "'");
            }
        }
    }
}

Answer 1

这里有一个细微的变化，希望这会起作用。

 import java.io.File;
import java.util.ArrayList;
import java.io.*; 
public class MainClass
{
    public static void main(String[] args) throws IOException 
    {
    String s = null;
        ArrayList<String> lines = new ArrayList<String>();
        String dir = "C:\\Users\\ME\\Desktop\\XX" ;
        String line = null;
        File folder = new File(dir);
       String[] files = folder.list();
        for (String file : files) 
        {
            try {
            File f = new File(dir + "\\" +file);
          if (file.endsWith(".ind")){  
            FileReader fileReader =  new FileReader(f);
            // Always wrap FileReader in BufferedReader.
            BufferedReader bufferedReader =  new BufferedReader(fileReader);
           // line = bufferedReader.readLine();
            while((line = bufferedReader.readLine()) != null) {
                if ( line.contains("GROUP_FILENAME:"))
        s = line.substring(0, 15) + "/HOME/FOLDER/" + line.substring(15);
      lines.add(s);
      System.out.println(s);
            }       
                fileReader.close();
                bufferedReader.close();
        FileWriter fw = new FileWriter(f);
        BufferedWriter out = new BufferedWriter(fw);
      for(String st : lines)
        out.write(st);
      out.flush();
      out.close();

          }         
        }
        catch(FileNotFoundException ex) {
            System.out.println( "Unable to open file '" + "'");                
        }    
        }
           }
}