How to have a code block for a case statement for a switch that assigns a value?

Question

As you know, Java 14 introduced Switch Expressions, switch statements that return a value. (See JEP 361.)

But it doesn't seem to work with case statements that have code blocks. I'm not sure if I don't have the syntax right or this is disallowed.

I'm curious because it would be inconsistent with non r-value switch statements (first example). Plus I've seen this in other languages.

    static void foo(String x) {
        // this works
        switch(x) {
            case "hi" -> {
                System.out.print("got hi");
                System.out.println("hello");
            }
            default -> System.out.println("bye");
        }

        // this works
        var y = switch(x) {
            case "hi" -> "hello";
            default -> "bye";
        };

        // is this possible?
        var z = switch(x) {
            case "hi" -> {
                System.out.println("got hi");
                return "hello";  // return "hello" to the z
            }
            default -> "bye";
        };
    }

Answer 1

yield, not return

Java 14 introduced a new yield statement as part of JEP 361: Switch Expressions.

Instead of return, use the restricted identifier yield.

See The Java® Language Specification for details.

Example code:

var z = switch(x) {
    case "hi" -> {
        System.out.println("got hi");
        yield "hello";
    }
    default -> "bye";
};

And this doesn't just work with switches with -> { ... }. You can use it in a labeled switch expression too:

var z = switch(x) {
    case "hi":
        System.out.println("got hi");
        yield "hello";
    default:
        yield "bye"
};

See also part 6 Switch Expressions of Java Language Updates.