File I/O

Byte streams use InputStream/OutputStream; character I/O uses Reader/Writer with a charset. NIO Path and Files provide concise filesystem operations.

Explicit encoding and cleanup

Path path = Path.of("notes.txt");
try (BufferedWriter writer = Files.newBufferedWriter(path, StandardCharsets.UTF_8)) {
    writer.write("Java\n");
}

try (Stream<String> lines = Files.lines(path, StandardCharsets.UTF_8)) {
    lines.forEach(System.out::println);
}

Buffer repeated small operations, check size before loading untrusted files, normalize and constrain user-controlled paths, and handle partial failure. Files.move can support temporary-file replacement. Never rely on the platform default charset for durable interchange. Streams from Files.lines hold resources and must be closed.