Java Calendar Between daysBetween(Calendar early, Calendar late)

Description

Returns the days between two dates.

License

Open Source License

Parameter

Parameter	Description
early	a parameter
late	a parameter

Return

the days between two dates.

Declaration

public static final int daysBetween(Calendar early, Calendar late) 

Method Source Code

//package com.java2s;

import java.util.Calendar;
import java.util.Date;

public class Main {
    /**//www  .ja  v a2  s .c  o m
     * Returns the days between two dates. Positive values indicate that
     * the second date is after the first, and negative values indicate, well,
     * the opposite. Relying on specific times is problematic.
     *
     * @param early the "first date"
     * @param late the "second date"
     * @return the days between the two dates
     */
    public static final int daysBetween(Date early, Date late) {

        Calendar c1 = Calendar.getInstance();
        Calendar c2 = Calendar.getInstance();
        c1.setTime(early);
        c2.setTime(late);

        return daysBetween(c1, c2);
    }

    /**
     * Returns the days between two dates. Positive values indicate that
     * the second date is after the first, and negative values indicate, well,
     * the opposite.
     *
     * @param early
     * @param late
     * @return the days between two dates.
     */
    public static final int daysBetween(Calendar early, Calendar late) {

        return (int) (toJulian(late) - toJulian(early));
    }

    /**
     * Return a Julian date based on the input parameter. This is
     * based from calculations found at
     * <a href="http://quasar.as.utexas.edu/BillInfo/JulianDatesG.html">Julian Day Calculations
     * (Gregorian Calendar)</a>, provided by Bill Jeffrys.
     * @param c a calendar instance
     * @return the julian day number
     */
    public static final float toJulian(Calendar c) {

        int Y = c.get(Calendar.YEAR);
        int M = c.get(Calendar.MONTH);
        int D = c.get(Calendar.DATE);
        int A = Y / 100;
        int B = A / 4;
        int C = 2 - A + B;
        float E = (int) (365.25f * (Y + 4716));
        float F = (int) (30.6001f * (M + 1));
        float JD = C + D + E + F - 1524.5f;

        return JD;
    }

    public static final float toJulian(Date date) {

        Calendar c = Calendar.getInstance();
        c.setTime(date);

        return toJulian(c);
    }
}

Related

1. daysBetween(Calendar early, Calendar late)
2. daysBetween(Calendar fromCalendar, Calendar untilCalendar)
3. daysBetween(Calendar fromDate, Calendar toDate)
4. daysBetween(Calendar start, Calendar end)
5. daysBetween(Calendar startTime, Calendar endTime)