[cempaka]

Java does have exhaustiveness checking on switch expressions over sealed types in the release JDK, but not switch statements (due to the requirement for backwards compatibility). I'll often find myself writing var _ = <some switch>; to get around this, a very Java idiom if ever there was one, heh

[za3faran]

Java does have exhaustiveness checking on switch statements for sealed types, but not enums (for backward compatibility), which is probably what you're using.

Try this:

    sealed interface Shape permits Circle, Rectangle { }
    record Circle(double radius) implements Shape { }
    record Rectangle(double length, double width) implements Shape { }

    void test() {
        Shape shape = new Circle(5);
        switch (shape) {
            case Circle _ -> System.out.println("Circle");
            case Rectangle _ -> System.out.println("Rectangle"); // Comment out this line to get an error.
        }
    }