java - 我如何在 Java 中更新文件，我应该使用哪个类？

Question

我的程序有以下代码，

BufferedWriter bufWriter = new BufferedWriter(new FileWriter(new File("xyz.dat"),true));
                        bufWriter.write(nameField+"/"+ageField+"/"+genderField+"\n");
                        bufWriter.flush();

这会创建一个文件..文件中存储的数据的示例格式..

Name1/Age1/Gender1                            // for user1
Name2/Age2/Gender2                            // for user2
.
.
.
NameN/AgeN/GenderN                            //for userN

假设我需要更改用户5的年龄那么我该怎么做？我可以导航到第五个用户，并且可以通过 split("/",3); 方法获取数据，但如何对该特定用户进行更改？我在这里真的很困惑。

Answer 1

1)用Java 7解决短文件(适合内存)

List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
String line5 = replaceAge(lines.get(4), newAge);
lines.set(4, line5);
Path tmp = Files.createTempFile(prefix, suffix, attrs);
Files.write(path, lines)
Files.move(tmp, path, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);

2) 对于大文件

    Path tmp = Files.createTempFile(prefix, suffix, attrs);
    try (BufferedWriter bw = Files.newBufferedWriter(path, StandardCharsets.UTF_8);
            BufferedReader br = Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
        String line;
        for (int i = 1; (line = br.readLine()) != null; i++) {
            if (i == 5) {
                line = replaceAge(line, newAge);
            }
            bw.write(line);
            bw.newLine();
        }
    }
    Files.move(tmp, path, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING);