Comments on: #JavaOne 2009 Return of the Puzzlers: Schlock and Awe

By: kirlich

kirlich — Mon, 15 Jun 2009 08:50:43 +0000

It is interesting to me that I was actually able to guess the outcome, but I’m convinced it was only because this is a puzzler, and I was expecting something like that. If it was causing bug somewhere in the actual code, then I’m sure I would have spent “interesting” hours debugging.

You could be interested in somewhat related article on my blog:
http://kirlich.wordpress.com/2008/12/27/where-is-the-ball/

By: Joel Neely

Joel Neely — Fri, 12 Jun 2009 11:40:56 +0000

Thanks, Matt! I probably would have been suckered into thinking that a null reference variable was an immutable (though pointless) constant. However…

There’s also a subtle violation of a symmetry/consistency principle there; in my eagerness to consume the source code (and prove my awesome Java mastery to myself I read line 10 as

public static final String SECOND = "null";

My experience is that skimming a list of highly-similar items can make the eye (at least mine…) insensitive to small but significant changes. So, while reading a list of “constant string” definitions, I thought I saw double quote punctuation around the null!

For me, another moral of this puzler is, “Things that are different should look different.” I’ve tried to make a habit of injecting something distinctive in the source code when I’m introducing a difference that matters (blank line, grouping, comment, deliberately breaking the vertical alignment, etc.)

By: Dimitris Andreou

Dimitris Andreou — Thu, 11 Jun 2009 10:49:02 +0000

Wow! Surprizing indeed!