Question

I am considering to use an enum with a static initializer like this:

public enum MyEnum{
    ...
    private static HashMap<X, Y> features;

    static {
        features.put(X, new (Y));
    }
    ...
}

Is the HashMap going to be reinitialized every time I need a value from it?

Answer 1

No, like all static blocks it’s executed only when the type is initialized.

So this will be done only once.

But you should affect a value to your map : you don’t do it in the code we see. You should have

private static Map<X, Y> features;

static {
    features = new HashMap<X, Y>();
    features.put(X, new Y());
}