Question

I want to declare static(or not static) variable inside Enum. I need this because I want to associate enum values with some strings. But i Don’t want to hardcode this strings. I want to use my application-wide class with String constants.
I.e. I want to write like this inside enum declaraton, but there compile time error:

public enum MyEnum {   
        private static final AppConstants CONSTANTS = AppConstants.getInstance();

        ONE(CONSTANTS.one()),
        TWO(CONSTANTS.two());
}

How I can put in enum a field?

Answer 1

It’s one of the limitations, the enum values must be specified first but you can always refer to the same singelton in every instantiation…

enum MyEnum {

    ONE(Test.getInstance().one()),
    TWO(Test.getInstance().two());

    public final String val;

    MyEnum(String val) { this.val = val; }
}

Example that outputs “hello”:

public class Test {
    public static void main(String[] args) {
        System.out.println(MyEnum.ONE.val);
    }

    public String one() {
        return "hello";
    }
    public String two() {
        return "world" ;
    }

    static Test instance;
    public synchronized static Test getInstance() {
        if (instance == null)
            instance = new Test();
        return instance;
    }
}