File IO

import java.nio.file.*;
import java.io.*;
import java.util.*;

// Write file
Files.writeString(Path.of("output.txt"), "Hello World");

// Read all lines
List<String> lines = Files.readAllLines(Path.of("input.txt"));

// Read line by line
try (Stream<String> stream = Files.lines(Path.of("data.txt"))) {
    stream.filter(line -> line.startsWith("#"))
          .forEach(System.out::println);
}

// Copy file
Files.copy(Path.of("src.txt"), Path.of("dest.txt"),
    StandardCopyOption.REPLACE_EXISTING);

// Create directory
Files.createDirectories(Path.of("a/b/c"));