// Version: Feb 2020
//
// The following Java program illustrates how easy it is to apply NexCalendar:
//
// Since software stores dates by its ordinal days from a special date,
// it is easy to convert any Gregorian date to NexCalendar date.
//
import java.util.*;
import java.time.*;
import java.time.format.*;
import java.text.DateFormatSymbols;
import java.io.*;
public class NexCalendar
{
// Weekday = Day of the Week (1 = Monday ... 7 = Sunday, 8 = Sunday)
// Yearday = Ordinal Day of the Year (1 ... 365, 366 = Leap Sunday)
public static final int maxdaysInYear = 366; // 366 is equal to the Leap Sunday
public static final int daysByWeek35 = 35 * 7 + 1; // It is the annual long week with 8 days
public static final int[] daysInMonths = { 0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
public static final int[] daysByMonths = { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 };
private static boolean invalidInt(int x, int max) { return (x < 1 || x > max); }
public static int getYeardayFromMonthDay(int month, int day)
{
if (invalidInt(month, 12) || invalidInt(day, daysInMonths[month])) return 0;
return (daysByMonths[month - 1] + day);
}
public static int[] getMonthDay(int yearday) // [0] = month, [1] = day
{
if (invalidInt(yearday, maxdaysInYear)) return new int[] {0,0};
int month = 2;
if (yearday > daysByMonths[4]) month = 6;
if (yearday > daysByMonths[8]) month = 10;
if (yearday > daysByMonths[month]) month++; else month--;
if (yearday > daysByMonths[month]) month++;
return new int[] {month, yearday - daysByMonths[month - 1]};
}
public static int getYeardayFromWeekDate(int week, int weekday)
{
if (week == 35 && weekday == 8) return daysByWeek35;
if (week == 52 && weekday == 8) return maxdaysInYear;
if (invalidInt(week, 52) || invalidInt(weekday, 7)) return 0;
int yearday = (week - 1) * 7 + weekday;
if (week > 35) yearday++;
return yearday;
}
public static int[] getWeekDate(int yearday) // [0] = week, [1] = weekday
{
if (invalidInt(yearday, maxdaysInYear)) return new int[] {0, 0}; // Unknown
if (yearday == maxdaysInYear) return new int[] {52, 8}; // The last week
if (yearday == daysByWeek35) return new int[] {35, 8}; // The last week
if (yearday >= daysByWeek35) yearday--;
int week = (1 + (yearday - 1) / 7);
int weekday = yearday - ((week - 1) * 7);
return new int[] {week, weekday};
}
public static int[] getWeekDateFromMonthDay(int month, int day) // [0] = week, [1] = weekday
{
return getWeekDate(getYeardayFromMonthDay(month, day));
}
public static int[] getMonthDayFromWeekDate(int week, int weekday) // [0] = month, [1] = day
{
return getMonthDay(getYeardayFromWeekDate(week, weekday));
}
public static String[] getWeekdayName(int week, int weekday) // [0] = LongName, [1] = ShortName
{
if ((week == 35 || week == 52) && weekday == 8) weekday = 7; // Special Sunday
if (invalidInt(week, 52) || invalidInt(weekday, 7)) return new String[] {"", ""};
if (weekday == 7) weekday = 0; // Sunday is 0
weekday++; // Sunday = 1, Saturday = 7
String longName = DateFormatSymbols.getInstance().getWeekdays()[weekday];
String shortName = DateFormatSymbols.getInstance().getShortWeekdays()[weekday];
return new String[] {longName, shortName};
}
public static boolean isLeapYear(int year)
{
return (year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0);
}
public static LocalDate newLocalDate(int year, int month, int day)
{
if (!isLeapYear(year))
{
if (invalidInt(month, 12))
throw new UncheckedIOException(new IOException("invalid Month"));
if (invalidInt(day, daysInMonths[month]))
throw new UncheckedIOException(new IOException("invalid Day"));
if (month == 12 && day == 31) ; // set the last day of the year
else if (month > 1 && day == daysInMonths[month]) { month++; day = 1; }
else if (month > 2) day++;
}
return LocalDate.of(year, month, day);
}
public static Date newDate(int year, int month, int day)
{
LocalDate localDate = newLocalDate(year, month, day);
return Date.from(localDate.atStartOfDay(ZoneId.systemDefault()).toInstant());
}
public static String toString(LocalDate date, String format)
{
String d = "@";
int diff = 0;
int day = date.getDayOfMonth();
int month = date.getMonthValue();
int year = date.getYear();
int dayOfYear = date.getDayOfYear();
int[] weekDate = NexCalendar.getWeekDate(dayOfYear);
String[] weekdayName = NexCalendar.getWeekdayName(weekDate[0], weekDate[1]);
if (!isLeapYear(year) && month > 2)
{ // the previous day
diff = -1; day--;
if (day == 0) day = NexCalendar.daysInMonths[(month - 1)];
}
date = date.plusDays(diff);
format = format.replaceAll("d",d);
format = format.replaceAll("EEEE", d+d+d+d);
format = format.replaceAll("E+", d+d+d);
String output = date.format(DateTimeFormatter.ofPattern(format));
output = output.replaceAll(d + d + d + d, weekdayName[0]); // longName
output = output.replaceAll(d + d + d, weekdayName[1]); // shortName
output = output.replaceAll(d + d, (day < 10? "0"+day : ""+day));
output = output.replaceAll(d, ""+day);
return output;
}
public static String toString(Date date, String format)
{
LocalDate localDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
return toString(localDate, format);
}
// e.g.
public static void main(String[] args)
{
LocalDate date = NexCalendar.newLocalDate(2021,2,29);
int[] monthDay = NexCalendar.getMonthDay(date.getDayOfYear());
int[] weekDate = NexCalendar.getWeekDate(date.getDayOfYear());
String[] weekdayName = NexCalendar.getWeekdayName(weekDate[0], weekDate[1]);
System.out.println("Month: " + monthDay[0] + " Day: " + monthDay[1]);
System.out.println("Week: " + weekDate[0] + " Weekday: " + weekDate[1]);
System.out.println("It is " + weekdayName[0] + " (" + weekdayName[1] + ")");
System.out.println(NexCalendar.toString(date,"d-MMM-yyyy d dd E EEEE"));
}
}
// Copyright © 2020 Dr. Donny C.F. Lai & Justin J.S. Lai. All Rights Reserved.