Java Date Difference dayDiffByStartOfDay(Date a, Date b)

Description

day Diff By Start Of Day

License

Open Source License

Declaration

public static long dayDiffByStartOfDay(Date a, Date b) 

Method Source Code

//package com.java2s;
/*/*w  ww  .ja  v  a2s  .  co  m*/
 * #%L
 * Webstar Newsletter
 * %%
 * Copyright (C) 2013 Webstar Csoport Kft.
 * %%
 * 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 General Public 
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/gpl-3.0.html>.
 * #L%
 */

import java.util.*;

public class Main {
    public static final long HOUR_IN_MILLIS = 60 * 60 * 1000;
    public static final long DAY_IN_MILLIS = 24 * HOUR_IN_MILLIS;

    public static long dayDiffByStartOfDay(Date a, Date b) {
        a = startOfDay(a);
        b = startOfDay(b);
        return dayDiff(a, b);
    }

    public static Date startOfDay(Date datum) {
        if (datum == null) {
            return null;
        }
        Calendar cal = new GregorianCalendar();
        cal.setTime(datum);
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MILLISECOND, 0);

        return cal.getTime();
    }

    public static long dayDiff(Date a, Date b) {
        if (a == null || b == null) {
            return 0;
        }

        long diff = a.getTime() - b.getTime();

        //egy orat a teli-nyari idoszamitas miatt korrigalunk (van 23 oras nap is)
        if (diff >= 0) {
            diff = diff + HOUR_IN_MILLIS;
        } else {
            diff = diff - HOUR_IN_MILLIS;
        }

        return diff / DAY_IN_MILLIS;
    }
}

Related

1. dateDiffMonth(Date d1, Date d2)
2. dateDiffWithNow(Calendar sDate)
3. dayDiff(Date a, Date b)
4. dayDiff(Date date1, Date date2)
5. dayDiff(Date first, Date second)
6. daysDiff(Date d1, Date d2)
7. diff(Date d1, Date d2)
8. diff(Date date1, Date date2)
9. diff(Date date1, Date date2)