无法在 Java 中删除文件

Question

由于某种原因无法删除和替换文件。

我只想从文件中删除 1 行。我找到了一种方法，方法是创建一个临时文件，然后从原始文件中逐行写入每一行，除了我要删除的行，然后用临时文件替换原始文件，但是虽然临时文件是创建的，但原始文件不能由于某种原因被删除和替换。我检查了文件没有打开。

File inputFile = new File("epafes.txt");
File tempFile = new File("epafesTemp.txt");

BufferedReader reader2 = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));

String lineToRemove = del;
String currentLine;

while((currentLine = reader2.readLine()) != null) {
    // trim newline when comparing with lineToRemove
    String trimmedLine = currentLine.trim();
    if(trimmedLine.equals(lineToRemove)) continue;
    writer.write(currentLine + System.getProperty("line.separator"));
}
writer.close();
reader2.close(); 
if (!inputFile.delete()) {
            System.out.println("Could not delete file");
            return;
        }

        //Rename the new file to the filename the original file had.
        if (!tempFile.renameTo(inputFile))
            System.out.println("Could not rename file");
        }

Answer 1

强烈建议使用java.nio.file.Files#delete(Path) 方法而不是File#delete。阅读相关的question。此外，您不必删除文件并写入临时文件。只需阅读文本，根据需要对其进行过滤，最后从头开始重新编写相同的文件。 （当然写入必须先关闭。）

看看这个例子：

public class ReadWrite {
    public static void main(String[] args) {
        File desktop = new File(System.getProperty("user.home"), "Desktop");
        File txtFile = new File(desktop, "hello.txt");
        StringBuilder sb = new StringBuilder();
        try (BufferedReader br = new BufferedReader(new FileReader(txtFile))) {
            String line;
            while ((line = br.readLine()) != null) {
                if ("this should not be read".equals(line))
                    continue;
                sb.append(line);
                sb.append(System.lineSeparator());
            }
        } catch (IOException e) {
            System.err.println("Error reading file.");
            e.printStackTrace();
        }

        try (PrintWriter out = new PrintWriter(txtFile)) {
            out.write(sb.toString());
        } catch (IOException e) {
            System.err.println("Error writing to file.");
            e.printStackTrace();
        }
    }
}

初始hello.txt内容：

hello there
stackoverflow
this should not be read
but what if it does?
then my answer
is going to get downvotes

运行后：

hello there
stackoverflow
but what if it does?
then my answer
is going to get downvotes

P.S：如果您使用的是 Java 8+，请查看 try-with resources 和 AutoClosable.