Java Calendar Different diffDays(Calendar startDate, Calendar endDate)

Description

Returns the number of days between the specified start date and end date.

License

MIT License

Parameter

Parameter	Description
startDate	a start date.
endDate	an end date.

Return

the number of days between the specified start date and end date.

Declaration

public static long diffDays(Calendar startDate, Calendar endDate) 

Method Source Code

//package com.java2s;
/*//from  ww w.j a  v a 2 s.c o m
 * Copyright (c) 2015-2016 QuartzDesk.com.
 * Licensed under the MIT license (https://opensource.org/licenses/MIT).
 */

import java.util.Calendar;

public class Main {
    /**
     * Returns the number of days between the specified start date and end date.
     * If the end date precedes the start date, then this method returns 0.
     * Inspired by the <a href="http://tripoverit.blogspot.com/2007/07/java-calculate-difference-between-two.html">
     * Java - calculate the difference between two dates</a> article.
     *
     * @param startDate a start date.
     * @param endDate   an end date.
     * @return the number of days between the specified start date and end date.
     */
    public static long diffDays(Calendar startDate, Calendar endDate) {
        Calendar sDate = (Calendar) startDate.clone();
        long daysBetween = 0;

        int y1 = sDate.get(Calendar.YEAR);
        int y2 = endDate.get(Calendar.YEAR);
        int m1 = sDate.get(Calendar.MONTH);
        int m2 = endDate.get(Calendar.MONTH);

        //**year optimization**
        while (((y2 - y1) * 12 + (m2 - m1)) > 12) {
            //move to Jan 01
            if (sDate.get(Calendar.MONTH) == Calendar.JANUARY
                    && sDate.get(Calendar.DAY_OF_MONTH) == sDate.getActualMinimum(Calendar.DAY_OF_MONTH)) {

                daysBetween += sDate.getActualMaximum(Calendar.DAY_OF_YEAR);
                sDate.add(Calendar.YEAR, 1);
            } else {
                int diff = 1 + sDate.getActualMaximum(Calendar.DAY_OF_YEAR) - sDate.get(Calendar.DAY_OF_YEAR);
                sDate.add(Calendar.DAY_OF_YEAR, diff);
                daysBetween += diff;
            }
            y1 = sDate.get(Calendar.YEAR);
        }

        //** optimize for month **
        //while the difference is more than a month, add a month to start month
        while ((m2 - m1) % 12 > 1) {
            daysBetween += sDate.getActualMaximum(Calendar.DAY_OF_MONTH);
            sDate.add(Calendar.MONTH, 1);
            m1 = sDate.get(Calendar.MONTH);
        }

        // process remainder date
        while (sDate.before(endDate)) {
            sDate.add(Calendar.DAY_OF_MONTH, 1);
            daysBetween++;
        }

        return daysBetween;
    }
}

Related

1. dateDiff(int type, Calendar fromDate, Calendar toDate, boolean future)
2. dateDiff(long dateUtilitiesUnitField, Calendar firstDate, Calendar secondDate)
3. dateDifferenceInMin(Calendar startDate, Calendar stopDate)
4. diff(Calendar value1, Calendar value2, int millisInCondition)
5. diffDay(Calendar calendar, int day)
6. differenceInDays(Calendar date1, Calendar date2)
7. formatTimeDiff(Calendar ref, Calendar now, boolean ignoreMS)
8. getDateDiff(Calendar c1, Calendar c2)
9. getDateDiff(Calendar d1, Calendar d2)