Record Classes for Data Carriers

import java.util.List;
import java.util.Objects;

public class RecordClasses {

    public record Point(int x, int y) {
        public Point {
            if (x < 0 || y < 0) {
                throw new IllegalArgumentException(
                    "Coordinates must be non-negative");
            }
        }

        public double distanceTo(Point other) {
            return Math.sqrt(
                Math.pow(x - other.x, 2) +
                Math.pow(y - other.y, 2)
            );
        }
    }

    public record Rectangle(Point topLeft, Point bottomRight) {
        public int width() {
            return bottomRight.x() - topLeft.x();
        }
        public int height() {
            return bottomRight.y() - topLeft.y();
        }
        public int area() {
            return width() * height();
        }
    }

    public record Employee(
        String name,
        String department,
        double salary,
        List<String> skills
    ) {
        public Employee {
            Objects.requireNonNull(name);
            skills = List.copyOf(skills);
        }
    }

    public static void main(String[] args) {
        Point p1 = new Point(0, 0);
        Point p2 = new Point(3, 4);
        System.out.println("Distance: " + p1.distanceTo(p2));

        Rectangle rect = new Rectangle(p1, p2);
        System.out.println("Area: " + rect.area());

        Employee emp = new Employee("Alice", "Engineering", 95000,
            List.of("Java", "Python", "SQL"));
        System.out.println(emp);
    }
}