Description
Converts a Julian Day into a GregorianCalendar
License
Open Source License
Parameter
| Parameter | Description |
|---|
| jd | the Julian Day |
Exception
| Parameter | Description |
|---|
| IllegalArgumentException | thrown when Julian Day is negative |
Return
a GregorianCalendar for the given Julian Day
Declaration
public static GregorianCalendar convertJulianDayToCalendar(double jd)
throws IllegalArgumentException, ParseException
Method Source Code
/*/*from www . ja v a 2 s . c om*/
* Copyright (C) 2011-2012 Inaki Ortiz de Landaluce Saiz
*
* This program is free software: you can redistribute it
* and/or modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, either
* version 3 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program. If not, see
* <http://www.gnu.org/licenses/>
*/
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
public class Main{
/**
* Converts a Julian Day into a GregorianCalendar
*
* @param jd
* the Julian Day
* @return a GregorianCalendar for the given Julian Day
* @throws IllegalArgumentException
* thrown when Julian Day is negative
*/
public static GregorianCalendar convertJulianDayToCalendar(double jd)
throws IllegalArgumentException, ParseException {
if (jd < 0) {
throw new IllegalArgumentException("Unsupported argument " + jd
+ ". Julian Day must be positive");
}
// calculate integer and decimal parts of jd + 0.5
double j = jd + 0.5;
int z = (int) j;
double f = j % 1;
int a = 0;
if (z < 2299161) {
a = z;
} else {
int alpha = (int) ((z - 1867216.25) / 36524.25);
a = z + 1 + alpha - (int) (alpha / 4);
}
int b = a + 1524;
int c = (int) ((b - 122.1) / 365.25);
int d = (int) (365.25 * c);
int e = (int) ((b - d) / 30.6001);
double day = b - d - (int) (30.6001 * e) + f;
int month;
if (e < 14) {
month = e - 1;
} else {
month = e - 13;
}
int year;
if (month > 2) {
year = c - 4716;
} else {
year = c - 4715;
}
return DateTimeUtils.parseCalendar(year, month, day,
DateTimeUtils.getGmtTimeZone());
}
/**
* Parses a date assuming all arguments are based on a Gregorian or Julian
* calendar.
*
* @param year
* year value
* @param month
* month of the year (first month is 1)
* @param day
* day of the month including fraction of hours, minutes, seconds
* and milliseconds
* @param zone
* the given time zone
* @return a calendar
*/
public static GregorianCalendar parseCalendar(int year, int month,
double day, TimeZone zone) {
// calculate hour, minutes, seconds and milliseconds
double hour = (day % 1) * 24; // decimal part of a day times 24
double minute = (hour % 1) * 60; // decimal part of an hour times 60
double second = (minute % 1) * 60; // decimal part of a minute times 60
double millisecond = (second % 1) * 1000;
return parseCalendar(year, month, (int) day, (int) hour,
(int) minute, (int) second, (int) Math.round(millisecond),
zone);
}
/**
* Parses a date assuming all arguments are based on a Gregorian calendar.
*
* @param year
* year value
* @param month
* month of the year (first month is 1)
* @param day
* day of the month (first day is 1)
* @param hour
* hour of the day for the 24-hour clock
* @param minute
* minute value within the hour
* @param second
* second value within the minute
* @param millisecond
* milliseconds value within the second
* @param zone
* the given time zone
* @return a Gregorian calendar
*/
public static GregorianCalendar parseCalendar(int year, int month,
int day, int hour, int minute, int second, int millisecond,
TimeZone zone) {
GregorianCalendar calendar = new GregorianCalendar(zone);
calendar.set(Calendar.YEAR, year);
calendar.set(Calendar.MONTH, month - 1);
calendar.set(Calendar.DAY_OF_MONTH, (int) day);
calendar.set(Calendar.HOUR_OF_DAY, (int) hour);
calendar.set(Calendar.MINUTE, (int) minute);
calendar.set(Calendar.SECOND, (int) second);
calendar.set(Calendar.MILLISECOND, (int) Math.round(millisecond));
return calendar;
}
/**
* Returns the GMT time zone
*
* @return the GMT time zone
*/
public static TimeZone getGmtTimeZone() {
return TimeZone.getTimeZone("GMT");
}
}