Working with Records (Java 14+)

public record Point(double x, double y) { }
Point p = new Point(1.0, 2.0);
double x = p.x();

public record Range(int lo, int hi) {
    public Range {
        if (lo > hi) throw new IllegalArgumentException("lo > hi");
    }
}

public record Pair<A, B>(A first, B second) {
    public <C> Pair<A, C> withSecond(C c) { return new Pair<>(first, c); }
}

sealed interface Shape permits Circle, Rect { }
record Circle(double r) implements Shape { }
record Rect(double w, double h) implements Shape { }

double area = switch (s) {
    case Circle(double r) -> Math.PI * r * r;
    case Rect(double w, double h) -> w * h;
};

List<String> topNames(List<User> users) {
    record Score(String name, int s) { }
    return users.stream()
        .map(u -> new Score(u.name(), u.points()))
        .sorted(Comparator.comparingInt(Score::s).reversed())
        .map(Score::name).limit(10).toList();
}