Use of enum in switch case but not as switch-argument

Question

I want to use the following enum as reference in a switch case:

public final enum myEnum {
    VALUE1,
    VALUE2,
    VALUE2,
    ...
}

I searched the internet already quite some time, but found only examples where the enum is used in the switch statement and the case stament as argument. I want to use only the values of the enum as argument of the case statements, the switch argument is another variable. Something like this:

String otherVariable = "VALUE2";
switch (otherVariable) {
    case myEnum,VALUE1.toString():
        ...
        break;
    case myEnum,VALUE2.toString():
        ...
        break;
    default:
        ...
        break;

When I code this straight forward, I get an error "case expressions must be constant expressions". What am I doing wrong? How do I implement this?

Kind regards WolfiG

daniu · Accepted Answer · 2018-05-08 11:48:25Z

6

What you want is probably

String other = "VALUE2";

MyEnum myEnum = MyEnum.valueOf(other);
switch (myEnum) {
    case VALUE1:
    ...
    case VALUE2:
    ...
}

You can't use myEnum.toString() because it's a method call, which can create different results between calls (ie non-constant).

edited May 8, 2018 at 11:48

answered May 8, 2018 at 11:16

daniu

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3 Comments

WolfiG Over a year ago

Hi daniu, nope, this doesn't work. Now I get an error: "cannot convert from MyEnum to MyEnum. Maybe it is worth noting that the enum is declared as member of a class and I call the enum in a method of that class.

daniu Over a year ago

@WolfiG Sorry, had a typo in my case statements. I'm not sure what you mean by "member of a class"; an enum (such as MyEnum) is a class by itself basically, so you can only have an inner enum; or you can have a value of the enum as a member, which shouldn't really make a difference.

WolfiG Over a year ago

You are right about the inner enum. And I found the trick: as the case attributes you need to use VALUE1 instead of MyEnum.VALUE1. Maybe you adjust your answer.

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