Question

我一直在致力于从多个.txt文件中读取数据以将其转换为.csv文件的项目。我的问题是，导出的数据不断覆盖第一行，因此每次我导出文件时，它仅显示最后一行。有人有任何提示可以帮助我吗？

//Reading the information from the files.
for (String fileName : textFileNames) {
  try (Scanner sc = new Scanner(new File(stack + "\\" + fileName));) {
    fileIn = sc.nextLine();

    while (fileIn != null) {
      String line = fileIn;
      String[] split = line.split("\\s+");
      StringJoiner joiner = new StringJoiner(",");

      for (String strVal : split) {
        joiner.add(strVal);
      }

      line = joiner.toString();
      line = line.startsWith(",") ? line.substring(1) : line;
      System.out.println(line);

      BufferedWriter br = new BufferedWriter(new FileWriter("myfile.csv"));
      StringBuilder sb = new StringBuilder();

      // Append strings from array
      sb.append(line);
      sb.append("\n");


      br.write(sb.toString());
      br.close(); 

      fileIn = sc.nextLine();
    } 


    sc.close();

  } catch (IOException ex) {
    Logger.getLogger(Class_Organizer_Krause.class.getName())
          .log(Level.SEVERE, null, ex);
  }

}

Answer 1

您正在while循环中重新创建BufferedWriter，实际上是每次您循环到输入文件中的新行时都重新创建文件。

将BufferedWriter的构造移出while循环（在其之前），将close语句移至while循环之后，这应该没问题。

Answer 2

BufferedWriter br = new BufferedWriter(new FileWriter("myfile.csv", true));应该可以解决您的问题。

这里是documentation

通过这种方式，您应该将这些创建的资源移至try https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html内，以免发生异常时拥有未封闭的资源

try (Scanner sc = new Scanner(new File(stack + "\\" + fileName));
     FileWriter fw = new FileWriter("myfile.csv", true);
     BufferedWriter br = new BufferedWriter(fw);
) {
 ...
 // you can remove br.close(); 
}

将.txt文件转换为一个.csv文件。导出的信息将覆盖第一行。有提示吗？

2 个答案: