code: private void setWorkingDay(ProjectCalendar mpxjCalendar, Day mpxjDay, String plannerDay)
     {
        DayType dayType = DayType.DEFAULT;
  
        if (plannerDay != null)
        {
           switch (getInt(plannerDay))
           {
              case 0:
              {
                 dayType = DayType.WORKING;
                 break;
              }
  
              case 1:
              {
                 dayType = DayType.NON_WORKING;
                 break;
              }
           }
        }
  
        mpxjCalendar.setWorkingDay(mpxjDay, dayType);
     }
docs: Set the working/non-working status of a weekday.
  
  @param mpxjCalendar MPXJ calendar
  @param mpxjDay day of the week
  @param plannerDay planner day type