Detect months with 31 days

Question

Is there an analogous form of the following code:

if(month == 4,6,9,11)
{
  do something;
}

Or must it be:

if(month == 4 ||         


        

Answer 1

I think your code will be more self-documenting if you use the static constants built into Calendar (e.g., Calendar.JANUARY, etc.)

If you do this often - more than once - I'd recommend writing a method named has31Days() or isReportMonth() to do the check in one place.

UPDATE:

The important thing isn't the months that have 31 days - it's the business rule that tells you something about reports for those months.

I might write it like this (hope I got the months with 31 days right):

public class ReportEngine
{
    public boolean isReportRequired(int month)
    {
        if ((month < Calendar.JANUARY) || (month > Calendar.DECEMBER))
            throw new IllegalArgumentException("Invalid month: " + month);

        // Reports are required for months with 31 days.
        return ((month == Calendar.JANUARY) || 
                (month == Calendar.MARCH) || 
                (month == Calendar.MAY) ||
                (month == Calendar.JULY) || 
                (month == Calendar.AUGUST) || 
                (month == Calendar.OCTOBER) ||
                (month == Calendar.DECEMBER));
    }
}