Switch expressions

Key points

• Arrow labels case X -> ... never fall through, so there is no break to forget.
• A switch expression produces a value, so you can assign or return it directly.
• Group labels with commas: case 12, 1, 2 -> "winter";.
• Need several statements? Use a block and yield the result out of it.
• Switch expressions must be exhaustive. Over an enum, cover every constant and skip default so a new constant becomes a compile error.
• Switch works on int, char, String and enums — and on types via pattern matching in Java 21.

Example

public class Main {

    enum Status { NEW, PAID, SHIPPED, CANCELLED }

    static int daysToDeliver(Status s) {
        return switch (s) {
            case NEW, PAID -> 3;
            case SHIPPED -> 1;
            case CANCELLED -> {
                System.out.println("  cancelled orders never ship");
                yield -1;
            }
        };
    }

    public static void main(String[] args) {
        for (Status s : Status.values()) {
            System.out.println(s + " -> " + daysToDeliver(s) + " day(s)");
        }

        int month = 4;
        String season = switch (month) {
            case 12, 1, 2 -> "winter";
            case 3, 4, 5 -> "spring";
            case 6, 7, 8 -> "summer";
            default -> "autumn";
        };
        System.out.println("month " + month + " is " + season);
    }
}

Arrow switch returns a value, never falls through and needs no break.