Java-Advanced/datetime/JavaJulianDayEx.java at master · tooltail/Java-Advanced

40 lines (28 loc) · 1.33 KB

package com.zetcode;

import java.time.LocalDate;

import static java.time.temporal.ChronoUnit.DAYS;

import java.time.temporal.JulianFields;

import java.util.Date;

// Julian day is the continuous count of days since the beginning of the

// Julian Period and is used primarily by astronomers, and in software for

// easily calculating elapsed days between two events

// The Julian Day Number (JDN) is the integer assigned to a whole solar day

// in the Julian day count starting from noon Universal time, with Julian day

// number 0 assigned to the day starting at noon on Monday, January 1, 4713 BC.

public class JavaJulianDayEx {

public static void main(String[] args) {

// Date cannot represent historical dates

var mdt = new Date(1812, 9, 7);

System.out.println(mdt);

var date = LocalDate.now();

long todayJulianDay = date.getLong(JulianFields.JULIAN_DAY);

System.out.println(todayJulianDay);

var borodinoBattle = LocalDate.of(1812, 9, 7);

System.out.println(borodinoBattle);

long borodinoJulianDay = borodinoBattle.getLong(JulianFields.JULIAN_DAY);

System.out.println(borodinoJulianDay);

System.out.println(todayJulianDay - borodinoJulianDay);

long daysBetween = DAYS.between(borodinoBattle, date);

System.out.println(daysBetween);

}

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