New JEP: Switch Expressions for the Java Language

[Brian Goetz]

> to summarize,
> we enhance le old switch by adding comma separated list of case values and by adding null as a possible pattern, and a warning if there is no default or the default is not at the ends,
> then we add an expression switch which extends the old switch as a poly expression with no fall through (make no sense), no weird scoping rules, the compiler emits an error if the switch is not exhaustive (need a default at the end apart for enums).

Right.

> what i'm currently doing with switch is using statement switch + return as a poor's man expression switch

Very common!
> I tend to refactor by introducing a method
Essentially, trying to make DA work for you.
> But if we support expression block in the expression switch, the two forms are very close syntactically,
> by example, can you find the difference between
>    return switch(name) {
>        case "red" -> {
>          return Color.RED;
>        };
>        case "blue" -> {
>          return Color.BLUE;
>        };
>        default -> {
>          throw new AssertionError("invalid " + name);
>        };
>    };
> and
>    switch(name) {
>        case "red": {
>          return Color.RED;
>        };
>        case "blue": {
>          return Color.BLUE;
>        };
>        default: {
>          throw new AssertionError("invalid " + name);
>        };
>    };
> this is far from obvious, and as a dev you have to because the semantics are differents.

The main difference is the unfortunate pun between local and nonlocal 
return.

> I wonder if we should either make the syntactic difference more clear

Open to suggestions.