Yield

To use a "switch expression" you put the entire switch to the right hand side of an equals sign¹ and, instead of assigning to a variable, you "yield" the value you want to assign.

enum StopLight {
    RED,
    YELLOW,
    GREEN
}

enum Action {
    STOP,
    SLOW_DOWN,
    GO
}

void main() {
    StopLight light = StopLight.GREEN;

    Action action = switch (light) {
        case RED -> {
            yield Action.STOP;
        }
        case YELLOW -> {
            yield Action.SLOW_DOWN;
        }
        case GREEN -> {
            yield Action.GO;
        }
    };

    System.out.println(action);
}

yield is very similar to return. The difference is that return will exit the entire method. yield just decides what the switch evaluates to.