Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Martin Gregorie <martin@address-in-sig.invalid>
Newsgroups: comp.lang.java.programmer
Subject: Re: How to handle same sanity checks
Date: Thu, 22 Jun 2017 10:27:18 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 41
Message-ID: <oig626$4rf$1@dont-email.me>
References: <87o9tgo0a9.fsf@munus.decebal.nl>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Thu, 22 Jun 2017 10:27:18 -0000 (UTC)
Injection-Info: mx02.eternal-september.org; posting-host="0d3e354b6e02414e6d46f69c40af244f"; logging-data="4975"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX18imvDhGTpMLlVgZrmdCYNcZBd8CK0Lf0s="
User-Agent: Pan/0.141 (Tarzan's Death; 168b179 git.gnome.org/pan2)
Cancel-Lock: sha1:wNUEaekBjlaIeY/ZucFbmt75Sds=
Xref: csiph.com comp.lang.java.programmer:36694

On Thu, 22 Jun 2017 11:10:38 +0200, Cecil Westerhof wrote:

> In my code I have several methods that start with:
>     if ((n < MIN_VAL) || (n > MAX_VAL)) {
>         throw new InvalidParameterException(String.format(ERROR_N, n));
>     }
> 
> That is not really DRY.
> 
> I could write a method like:
>     private void checkN(n) {
>         if ((n < MIN_VAL) || (n > MAX_VAL)) {
>             throw new InvalidParameterException(String.format(ERROR_N,
>             n));
>         }
>     }
> 
> And then replace all the checks with a call to checkN. But then the
> exception is generated in the method checkN instead of the method that
> has a wrong parameter.
> What is the best way to handle this?

I agree that using such a method would tidy up the calling code, but if I 
used this type of method I'd generalise it to something like this:

   private void checkInRange(int n, 
                             int lowLimit, 
                             int highLimit,
                             String error)
   {
      String format = "%s: %d is outside range %d - %d";
      if ((n < lowLimit) || (n > highLimit))
         throw new InvalidParameterException(
               String.format(format,error, n, lowLimit, highLimit));
   }


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |