尝试使用 java 从 .txt 文件中删除一行时收到异常和代码失败

Question

我正在尝试使用 java 从我的文本文件中删除特定行，我的代码应该将文件写入临时文件并跳过写入用户名（选择删除），它是然后应该删除原始文件并重命名新的临时文件以匹配原始文件。以下是我的代码：

 // remove a user
    public static void deleteUser() throws FileNotFoundException, IOException {
        System.out.println(
                "Are you sure you want to delete a user? WARNING this will permanently remove them from our database\nmeaning you won't be able to recover their user from our index.txt file. (y/n)");
        String answer = input.nextLine();
        if (Objects.equals(answer, "y")) {
            System.out.println("Please enter the exact username you would like to delete:");
            String username = input.nextLine();

            deleteUserFromFile(username, "index.txt", 1, " ");

            System.out.println("User deleted.");

        } else if (Objects.equals(answer, "n")) {
            menu();
        } else {
            System.out.println("The answer provided can't be read. Please answer again using 'y' or 'n'.");
            deleteUser();
        }
    }

    // remove user function
    public static void deleteUserFromFile(String username, String filepath, int positionOfTerm, String delimiter) {
        String tempFile = "temp.txt";
        File oldFile = new File(filepath);
        File newFile = new File(tempFile);

        String currentLine;
        String data[];

        try {
            FileWriter fw = new FileWriter(tempFile, true);
            BufferedWriter bw = new BufferedWriter(fw);
            PrintWriter pw = new PrintWriter(bw);

            FileReader fr = new FileReader(filepath);
            BufferedReader br = new BufferedReader(fr);

            while ((currentLine = br.readLine()) != null) {
                data = currentLine.split(delimiter);
                if (!(data[positionOfTerm].equalsIgnoreCase(username))) {
                    pw.println(currentLine);
                }
            }

            pw.flush();
            pw.close();
            fr.close();
            br.close();
            bw.close();
            fw.close();

            oldFile.delete();
            File dump = new File(filepath);
            newFile.renameTo(dump);

        } catch (Exception e) {
            System.out.println("An error occured.");
        }
    }

正在触发此代码的捕获，我不明白为什么。感谢您的帮助。

作为参考，这是我的索引文件：

6
0 Gromit
1 Gwendolyn
2 Le-Spiderman
3 Wallace
4 Batman
5 Superman

编辑：我已经包括 e.printStackTrace();按照建议，这是我从中收到的错误：

java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 1
        at Graph.deleteUserFromFile(Graph.java:239)
        at Graph.deleteUser(Graph.java:208)
        at Graph.menu(Graph.java:284)
        at Graph.main(Graph.java:302)

以下是参考代码，302:

        menu();

284:

        deleteUser();

208（这里的用户名是使用扫描输入收集的）：

deleteUserFromFile(username, "index.txt", 1, " ");

239:

if (!(data[positionOfTerm].equalsIgnoreCase(username))) {

编辑 2：

            while ((currentLine = br.readLine()) != null) {
                data = currentLine.split(delimiter);

                String numOfUsernamesInList = br.readLine(); // updating the username number counter at the top of the
                                                             // index file
                int newNumOfUsernamesInList = Integer.parseInt(numOfUsernamesInList) - 1;
                pw.println(String.valueOf(newNumOfUsernamesInList));

                if (data.length > positionOfTerm && !(data[positionOfTerm].equalsIgnoreCase(username))) {
                    pw.println(currentLine);
                }
            }

这是我试图让索引文件中显示的 6 保留并在从索引文件中删除用户名时更新为 5，以下是错误消息：

java.lang.NumberFormatException: For input string: "0 Gromit"
        at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.base/java.lang.Integer.parseInt(Integer.java:652)
        at java.base/java.lang.Integer.parseInt(Integer.java:770)
        at Graph.deleteUserFromFile(Graph.java:242)
        at Graph.deleteUser(Graph.java:208)
        at Graph.menu(Graph.java:290)
        at Graph.main(Graph.java:308)

Answer 1

第一行的

data[positionOfTerm]文件不存在。您需要先检查数组长度。

if (data.length > positionOfTerm && !(data[positionOfTerm].equalsIgnoreCase(username))) {

尝试使用 java 从 .txt 文件中删除一行时收到异常和代码失败

Receiving an exception and code failing when trying to delete a line from a .txt file using java

java

exception

file

filewriter

delete-file