java - 如何在 Java 中删除文本文件的最后一行？

Question

我有一个包含一些字符串的文件。例如:

迈克1111
克里斯2222
布莱恩3333

我正在尝试编写代码来从该文件中删除一行。但是，例如，当我删除 Chris 时，它会变成:

迈克1111
布莱恩3333
(空行)

空行是一个问题，因为当我添加另一个字符串时，它将出现在空行之后而不是在它的位置。先感谢您。这是我的代码:

public void deleteUser(String u, String p) throws IOException {
    username = u;
    pin = p;

    File userAccountFolder = new File("userLogin.txt");
    File temporaryFile = new File("temporaryFile.txt");

    BufferedReader buffReader = new BufferedReader(new FileReader(userAccountFolder));
    BufferedWriter buffWriter = new BufferedWriter(new FileWriter(temporaryFile));

    String lineToRemoveFromFile = username + pin;
    String lineFromUserFile;

    while ((lineFromUserFile = buffReader.readLine()) != null) {

        String trimmedLine = lineFromUserFile.trim();
        if (trimmedLine.equals(lineToRemoveFromFile)) {
          continue;
        }

        buffWriter.append(lineFromUserFile + System.getProperty("line.separator"));
    }
    buffWriter.close();
    buffReader.close();

    boolean removed = temporaryFile.renameTo(userAccountFolder);
    if (removed == true) {
        System.out.println(username + "'s account has been removed.");

    }

}

Answer 1

这可以解决问题，添加一个 boolean 检查。

        BufferedReader buffReader = new BufferedReader(new FileReader(userAccountFolder));
        BufferedWriter buffWriter = new BufferedWriter(new FileWriter(temporaryFile));

        String lineToRemoveFromFile = username + pin;
        String lineFromUserFile;

        boolean addnewLine = false;

        while ((lineFromUserFile = buffReader.readLine()) != null) {

            String trimmedLine = lineFromUserFile.trim();
            if (trimmedLine.equals(lineToRemoveFromFile)) {
                continue;
            }

            if (addnewLine) {
                buffWriter.newLine();
            } else {
                addnewLine = true;
            }
            buffWriter.append(lineFromUserFile);

        }
        buffWriter.close();
        buffReader.close();