Aug. 18, 2005 - Six / ten

This is real code.  Don´t laugh.

private static double six = 6;

private static double ten = 10;

 

/**

 * Utility method to convert int minutes to a decimal hours to

 * one decimal place.

 */

public String getHours( double minutes)

{

    double hours = java.lang.Math.round( minutes / six ) / ten;

    return String.valueOf(hours);

}

One has difficulty knowing where to start.  There are soooo many things wrong in just two lines of functional code.  Comments not matching function (int vs. decimal), bad function naming, possible missed opportunity to hold data in a Class, the possible use of the java Format class, the possible addition of a math library that would allow round( minutes / 60.0, 1), the list is just to big.

Let me just address the amazing use of six and ten.  Why would one possibly define quantities like six and ten?  I can only think of three possibilities. 

Possibility one: the coder is very concerned about possible future changes in the cardinal number naming system.  After all, just because 6 has implied the same quantity for a few thousand years one can never be sure that it might not change suddenly.

Possibility two: the coder has gotten religious about replacing concrete numbers with defined values (and yet not learned about the "final" keyword and capitalization conventions).  This is the worst kind of religion, pure form without understanding.  The advice is good but it doesn´t apply here.  The reason for using PI instead of 3.141592653589793d is that it is easier to type (accurately) and enhances meaning and readability.   

Even if the code was something like: "minutes = hours / MINUTES_PER_HOUR" I think you are complicating things.  "minutes = hours / 60.0"  is actually easier to read.  People will scan it and understand the meaning without any thought.  If it was "inches = feet * 12" the argument is less clear since some people will be unfamiliar with this conversion rate. 

Possibility three: the coder had to fix a bug and was just trying things.  This takes a bit of thinking, but bear with me as I follow the forensic trail.  The comment says it converts an "int minutes" so pretend that minutes is an int.  Taking that one assumption, it is possible that the code used to read: "double hours = java.lang.Math.round( minutes / 6) / 10;".  You´ve probably spotted the bug.  It´s the classic integer divide issue.  The round does nothing because the initial divide was in an integer context, so rounding would be "broken". 

If this was a very junior Java programmer, perhaps they couldn´t figure it out.  Perhaps they did but were unaware of how to express a number as anything but an integer (6.0, 6.0d, casting).  As they flailed away, they tried a lot of things and eventually got it to work.  This seems plausible to me, but in that case the lesson is clear.  If the answer works but feels wrong, go ask someone else!

Aug. 25, 2005 - safety in freedom

Aug. 25, 2005 - wrong article

Aug. 25, 2005 - Good points

Aug. 27, 2005 - Easier to read but wrong (and not really easier to read)

Aug. 27, 2005 - Insanely Funny