Question

I have enum like this

public enum Sizes {
    Normal(232), Large(455);

    private final int _value;

    Sizes(int value) {
        _value = value;
    }

    public int Value() {
        return _value;
    }
}

Now I can call Sizes.Normal.Value() to get integer value, but how do I convert integer value back to enum?

What I do now is:

public Sizes ToSize(int value) {
    for (Sizes size : Sizes.values()) {
        if (size.Value() == value)
            return size;
    }
    return null;
}

But that’s only way to do that? That’s how Java works?

Answer 1

Yes that’s how it’s done, generally by adding a static method to the enum. Think about it; you could have 10 fields on the enum. Do you expect Java to set up lookups for all of them?

The point here is that Java enums don’t have a ‘value’. They have identity and an ordinal, plus whatever you add for yourself. This is just different from C#, which follows C++ in having an arbitrary integer value instead.