How to throw an exception from an enum constructor

Question

(Referring to this post: How to throw an exception from an enum constructor?)

I would really like to do the same. Example Code:

public enum PublicIPWebservice {
    AMAZON_WEB_SERVICES("http://checkip.amazonaws.com"),
    EX_IP("http://api-ams01.exip.org/?call=ip"),
    WHAT_IS_MY_IP("http://automation.whatismyip.com/n09230945.asp");

private URL url;

private PublicIPWebservice(String url) throws MalformedURLException {
    this.url = new URL(url);
}

public URL getURL() {
    return url;
}
}

The program should crash if the url was not correct, as it would be a programming mistake, so catching the exception in the constructor would be wrong, wouldn't it?

What is the best way to solve that problem?

Answer 1

You can just catch it and rethrow as an AssertionError:

try {
    this.url = new URL(url);
}
catch(MalformedURLException e) {
    throw new AssertionError(e);
}