com.softicar.platform.common.date.ISOCalendar Maven / Gradle / Ivy
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package com.softicar.platform.common.date;
import java.util.Calendar;
import java.util.Locale;
import java.util.TimeZone;
/**
* Collection of date algorithms for years, months, weeks and days.
*
* This class contains only static functions and static data members. It depends
* on almost no other class.
*
* This uses a proleptic Gregorian calendar and is thus compatible to the MySQL
* function TO_DAYS. This means that this function assumes the Gregorian
* Calendar was used since the beginning of the universe.
*
* See the MySQL documentation for more detail.
*
* @author Oliver Richers
*/
public class ISOCalendar {
public static final int SECONDS_PER_DAY = 24 * 3600;
public static final Locale LOCALE = Locale.GERMANY;
public static final TimeZone TIME_ZONE = TimeZone.getTimeZone("Europe/Berlin");
static {
setDefaultTimeZone();
}
public static void setDefaultTimeZone() {
TimeZone.setDefault(TIME_ZONE);
}
// ******************************************************************************** //
// * get{Year,Month,Week}With{Month,Week,Day}(int) * //
// ******************************************************************************** //
/**
* Returns the year containing the specified month.
*
* @param month
* the absolute index of the month
* @return the absolute index of the year
*/
public static int getYearWithMonth(int month) {
return month / MONTHS_PER_YEAR;
}
/**
* Returns the absolute index of the year containing the specified week.
*
* @param week
* the absolute index of the week
* @return the absolute index of the year
*/
public static int getYearWithWeek(int week) {
int thursday = getFirstDayOfWeek(week) + Weekday.THURSDAY.getIndex() - 1;
return getYearWithDay(thursday);
}
/**
* Returns the absolute index of the year containing the specified day.
*
* @param day
* the absolute index of the day
* @return the absolute index of the year
*/
public static int getYearWithDay(int day) {
// approximate
int year = day / 365;
// year is greater than or equal to the actual year
while (day < getFirstDayOfYear(year)) {
--year;
}
return year;
}
/**
* Returns the month containing the specified week.
*
* @param week
* the absolute index of the week
* @return the absolute index of the month
*/
public static int getMonthWithWeek(int week) {
int thursday = getFirstDayOfWeek(week) + Weekday.THURSDAY.getIndex() - 1;
return getMonthWithDay(thursday);
}
// ******************************************************************************** //
// * getFirst{Month,Week,Day}Of{Year,Month,Week}(int) * //
// ******************************************************************************** //
/**
* Returns the first day of the specified year.
*
* @param year
* the absolute index of the year
* @return the absolute index of the first day
*/
public static int getFirstDayOfYear(int year) {
return 365 * year + (year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400;
}
/**
* Returns the first week of the specified year.
*
* @param year
* the absolute index of the year
* @return the absolute index of the week
*/
public static int getFirstWeekOfYear(int year) {
int firstDay = getFirstDayOfYear(year);
int week = getWeekWithDay(firstDay);
return getYearWithWeek(week) == year? week : week + 1;
}
/**
* Returns the first day of the specified month.
*
* @param month
* the absolute index of the month
* @return the absolute index of the first day of the month
*/
public static int getFirstDayOfMonth(int month) {
int indexWithinYear = getMonthIndexWithinYear(month);
MonthName monthName = MonthName.get(indexWithinYear);
int year = getYearWithMonth(month);
YearType yearType = YearType.getForYear(year);
return getFirstDayOfYear(year) + monthName.getStart(yearType) - 1;
}
/**
* Returns the first week of the specified month.
*
* @param month
* the absolute index of the month
* @return the absolute index of the week
*/
public static int getFirstWeekOfMonth(int month) {
int firstDay = getFirstDayOfMonth(month);
int week = getWeekWithDay(firstDay);
return getMonthWithWeek(week) == month? week : week + 1;
}
/**
* Returns the first day of the specified week.
*
* @param week
* the absolute index of the week
* @return the absolute index of the first day of the week
*/
public static int getFirstDayOfWeek(int week) {
return week * DAYS_PER_WEEK + FIRST_MONDAY;
}
// ******************************************************************************** //
// * getFirstAndLast{Month,Week,Day}Of{Year,Month,Week}(int) * //
// ******************************************************************************** //
/**
* Returns the first and the last day of the specified year.
*
* @param year
* the absolute index of the year
* @return the absolute indices of the days
*/
public static int[] getFirstAndLastDayOfYear(int year) {
YearType yearType = YearType.getForYear(year);
int[] days = new int[2];
days[0] = getFirstDayOfYear(year);
days[1] = days[0] + yearType.getDayCount() - 1;
return days;
}
public static int[] getFirstAndLastWeekOfYear(int year) {
int[] weeks = new int[2];
weeks[0] = getFirstWeekOfYear(year);
weeks[1] = getFirstWeekOfYear(year + 1) - 1;
return weeks;
}
/**
* Returns the first and last day of the specified month.
*
* @param month
* the absolute index of the month
* @return the absolute indices of the days
*/
public static int[] getFirstAndLastDayOfMonth(int month) {
int indexWithinYear = getMonthIndexWithinYear(month);
MonthName monthName = MonthName.get(indexWithinYear);
int year = getYearWithMonth(month);
YearType yearType = YearType.getForYear(year);
int[] result = new int[2];
result[0] = getFirstDayOfYear(year) + monthName.getStart(yearType) - 1;
result[1] = result[0] + monthName.getDayCount(yearType) - 1;
return result;
}
public static int[] getFirstAndLastWeekOfMonth(int month) {
int[] weeks = new int[2];
weeks[0] = getFirstWeekOfMonth(month);
weeks[1] = getFirstWeekOfMonth(month + 1) - 1;
return weeks;
}
/**
* Returns the first and last day of the specified week.
*
* @param week
* the absolute index of the week
* @return the absolute indices of the days
*/
public static int[] getFirstAndLastDayOfWeek(int week) {
int[] days = new int[2];
days[0] = getFirstDayOfWeek(week);
days[1] = days[0] + DAYS_PER_WEEK - 1;
return days;
}
// ******************************************************************************** //
// * getDayIndexWithin{Year,Month,Week}(int) * //
// * getDayOf{Year,Month,Week}(int, int) * //
// ******************************************************************************** //
/**
* Returns the index of the specified day within its year.
*
* @param day
* the absolute index of the day
* @return the relative index of the day [1,366]
*/
public static int getDayIndexWithinYear(int day) {
int year = getYearWithDay(day);
int firstDay = getFirstDayOfYear(year);
return day - firstDay + 1;
}
/**
* Returns the absolute index of the specified day.
*
* @param year
* the absolute index of the year
* @param day
* the index of the day within the year [1,366]
* @return the absolute index of the day
*/
public static int getDayOfYear(int year, int day) {
return getFirstDayOfYear(year) + day - 1;
}
/**
* Return the index of the specified day within its containing month.
*
* @param day
* the absolute index of the day
* @return the index of the day within its month
*/
public static int getDayIndexWithinMonth(int day) {
int month = getMonthWithDay(day);
int firstDay = getFirstDayOfMonth(month);
return day - firstDay + 1;
}
/**
* Returns the index of the specified day within its containing week.
*
* @param day
* the absolute index of the day
* @return the index of the day within its week [1,7]
*/
public static int getDayIndexWithinWeek(int day) {
// compute the distance to some monday
int result = (day - FIRST_MONDAY) % DAYS_PER_WEEK;
// the operator% returns the remainder which is in the range [-6,6]
// e.g. '-16 % 7 == -2' but we need '-16 mod 7 == 5'
if (result < 0) {
result += DAYS_PER_WEEK;
}
// week days go from 1 to 7
return result + 1;
}
/**
* Returns the specified day.
*
* @param month
* the absolute index of the month
* @param day
* the index of the day within the month [1,31]
* @return the absolute index of the day
*/
public static int getDayOfMonth(int month, int day) {
return getFirstDayOfMonth(month) + day - 1;
}
// ******************************************************************************** //
// * month * //
// ******************************************************************************** //
/**
* Returns the month containing the specified day.
*
* @param day
* the absolute index of the day
* @return the absolute index of the month
*/
public static int getMonthWithDay(int day) {
// get year of the day and its type
int year = getYearWithDay(day);
YearType yearType = YearType.getForYear(year);
// get month name
int indexWithYear = getDayIndexWithinYear(day);
MonthName monthName = yearType == YearType.NON_LEAP? DAY_TO_MONTH_MAP1[indexWithYear - 1] : DAY_TO_MONTH_MAP2[indexWithYear - 1];
return getMonthOfYear(year, monthName.getIndex());
}
/**
* Returns the index of the month within its year.
*
* @param month
* the absolute month index
* @return the relative month index
*/
public static int getMonthIndexWithinYear(int month) {
return month % MONTHS_PER_YEAR + 1;
}
/**
* Returns the absolute index of the specified month.
*
* @param year
* the absolute index of the year
* @param month
* the relative index of the month wihtin the year [1,12]
* @return the absolute index of the month
*/
public static int getMonthOfYear(int year, int month) {
return year * MONTHS_PER_YEAR + month - 1;
}
// ******************************************************************************** //
// * week * //
// ******************************************************************************** //
/**
* Returns the absolute index of the week containing the specified day.
*
* @param day
* some day of the returned week
* @return the absolute index of the week
*/
public static int getWeekWithDay(int day) {
if (day >= FIRST_MONDAY) {
return (day - FIRST_MONDAY) / DAYS_PER_WEEK;
} else {
return (day - FIRST_MONDAY + 1) / DAYS_PER_WEEK - 1;
}
}
/**
* Returns the index of the specified week within its year.
*
* @param week
* the absolute index of the week
* @return the index of the week [1,53]
*/
public static int getWeekIndexWithinYear(int week) {
int year = getYearWithWeek(week);
int firstWeek = getFirstWeekOfYear(year);
return week - firstWeek + 1;
}
/**
* Returns the index of the specified week within its month.
*
* @param week
* the absolute index of the week
* @return the index of the week [1,5]
*/
public static int getWeekIndexWithinMonth(int week) {
int month = getMonthWithWeek(week);
int firstWeek = getFirstWeekOfMonth(month);
return week - firstWeek + 1;
}
// ******************************************************************************** //
// * misc * //
// ******************************************************************************** //
public static Calendar getNewCalendar() {
return Calendar.getInstance(TIME_ZONE, LOCALE);
}
public static boolean isValidYMD(int year, int month, int day) {
if (day < 1 || month < 1 || month > 12) {
return false;
}
YearType yearType = YearType.getForYear(year);
MonthName monthName = MonthName.get(month);
return day <= monthName.getDayCount(yearType);
}
// ******************************************************************************** //
// * private * //
// ******************************************************************************** //
private static final int MONTHS_PER_YEAR = 12; // number of months in a year
private static final int DAYS_PER_WEEK = 7; // number of days in a week
private static final int FIRST_MONDAY = 2; // the first Monday of the year 0
private static final MonthName[] DAY_TO_MONTH_MAP1 = new MonthName[365];
private static final MonthName[] DAY_TO_MONTH_MAP2 = new MonthName[366];
static {
int i1 = 0;
int i2 = 0;
for (MonthName monthName: MonthName.values()) {
for (int j = 0; j != monthName.getDayCount(YearType.NON_LEAP); ++j) {
DAY_TO_MONTH_MAP1[i1++] = monthName;
}
for (int j = 0; j != monthName.getDayCount(YearType.LEAP); ++j) {
DAY_TO_MONTH_MAP2[i2++] = monthName;
}
}
}
}