switch.snippet

record Point(int x, int y) {}

record Circle(Point center, int radius) {
    public Circle {
        if (radius < 0) throw new IllegalArgumentException("Radius cant be null");
    }
}

ToDoubleFunction<Object> surface = object ->
    switch(object) {
        case null -> throw new AssertionError("Object is null");
        case Circle(Point p, int radius) when radius == 0 -> 0d;
        case Circle(Point p, int radius) -> Math.PI*radius*radius;
        case Object notACircle -> throw new AssertionError("Object is not a circle");
    };

Circle c1 = new Circle(new Point(0, 0), 0);
Circle c2 = new Circle(new Point(1, 1), 1);

System.out.println("Surface of " + c1 + " = " + surface.applyAsDouble(c1));
System.out.println("Surface of " + c2 + " = " + surface.applyAsDouble(c2));
surface.applyAsDouble(null);
surface.applyAsDouble("Not a circle!");