Is there a way to do switch expression fallthrough with lambda-like syntax for default case?

Question

What I'm trying to do is something like this, where a specific value & the default case can both map to a single value. I should clarify that the purpose of this is to be as explicit as possible. I understand that just using default would achieve the same functional result.

return switch(value) {
    case "A" -> 1;
    case "B" -> 2;
    case "ALL"
    default -> -1;
};

according the [Java Language Specification 15.28](https://docs.oracle.com/javase/specs/jls/se18/html/jls-15.html#jls-15.28) that is not possible (BTW that is a `switch expression` and not a `switch statement`) — user16320675, May 04 '22 at 16:43
Knowing what things are called generally helps with looking up the relevant information. — Karl Knechtel, May 04 '22 at 17:29

score 3 · Answer 1 · answered Jun 01 '22 at 09:19

3

This will be possible with Pattern Matching for switch which is already in a preview phase.

So when you use --enable-preview, the following works:

return switch(value) {
    case "A" -> 1;
    case "B" -> 2;
    case "ALL", default -> -1;
};

answered Jun 01 '22 at 09:19

Holger

285,553
42
434
765

score 1 · Answer 2 · answered May 27 '22 at 11:00

1

Combining default with a case is not possible and would be redundant (why the case then?), but combining cases with the lambda is possible:

return switch (value) {
    case "A", "B" -> 1;
    default -> -1;
};

answered May 27 '22 at 11:00

JRA_TLL

1,186
12
23

Is there a way to do switch expression fallthrough with lambda-like syntax for default case?

2 Answers2