java我有一个filewriter方法，它只在我关闭文件时输出到该文件

Question

字符串filePath=“Seat”

static void modifyFile(String filePath, String oldString, String newString) {
    File fileToBeModified = new File(filePath);

    String oldContent = "";

    BufferedReader reader = null;

    BufferedWriter writer = null;

    try {
        reader = new BufferedReader(new FileReader(fileToBeModified));

        //Reading all the lines of input text file into oldContent

        String line = reader.readLine();

        while (line != null) {
            oldContent = oldContent + line + System.lineSeparator();

            line = reader.readLine();
        }

        //Replacing oldString with newString in the oldContent

        String newContent = oldContent.replaceAll(oldString, newString);

        //Rewriting the input text file with newContent

        writer = new BufferedWriter(new FileWriter(fileToBeModified));


        writer.write(newContent);


        writer.flush();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            //Closing the resources

            reader.close();

            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

此方法用于更改文件中的某一行。该方法本身在运行时可以工作，但它仅在关闭程序时更改该行，即在关闭writer时，我查找该行并添加writer。在前面的代码中使用flush（）来查看这是否有效，但我仍然有同样的问题

Answer 1

您正在尝试读取和写入同一文件。 不能同时执行这两个操作，因为文件将被锁定。关闭读卡器，然后执行写入操作