NIO.2 provides Path and Files for modern file operations.

Path path = Path.of("data", "users.txt");

Files.writeString(
    path,
    "Alice\nBob\n",
    StandardOpenOption.CREATE,
    StandardOpenOption.TRUNCATE_EXISTING
);

String content = Files.readString(path);

Byte streams handle binary data; character readers/writers handle text. Buffered APIs reduce the cost of many small operations. For large files, stream line-by-line instead of loading the entire file.