Java Easter calculateEasterDay(int year)

Description

Calculates the easter day of given year.

License

Open Source License

Parameter

Parameter	Description
year	the given year

Return

the calculated easter day

Declaration

public static Date calculateEasterDay(int year) 

Method Source Code

//package com.java2s;
/*/*from w ww  .  j  a  va2s  . co  m*/
 * Utility class for a easy way to handle Date
 * Copyright (C) 2012 Martin Absmeier, IT Consulting Services
 *
 *  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/>.
 */

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

public class Main {
    /**
     * Calculates the easter day of given year.
     * 
     * @param year
     *            the given year
     * @return the calculated easter day
     */
    public static Date calculateEasterDay(int year) {
        int a = year % 19;
        int b = year % 4;
        int c = year % 7;
        int month = 0;

        int m = (8 * (year / 100) + 13) / 25 - 2;
        int s = year / 100 - year / 400 - 2;
        m = (15 + s - m) % 30;
        int n = (6 + s) % 7;

        int d = (m + 19 * a) % 30;

        if (d == 29) {
            d = 28;
        } else if (d == 28 && a >= 11) {
            d = 27;
        }

        int e = (2 * b + 4 * c + 6 * d + n) % 7;
        int day = 21 + d + e + 1;

        if (day > 31) {
            day = day % 31;
            month = 4;
        }
        if (day <= 31) {
            month = 3;
        }

        month++;
        return createDate(year, month, day);
    }

    /**
     * Creates a <code>java.util.Date</code> <b>without</b> time slice.
     * 
     * @param year
     *            the given year
     * @param month
     *            the given month
     * @param date
     *            the given date
     * @return the created <code>java.util.Date</code>.
     */
    public static Date createDate(int year, int month, int date) {
        return createDate(year, month, date, 0, 0, 0);
    }

    /**
     * Creates a <code>java.util.Date</code> <b>with</b> time slice.
     * 
     * @param year
     *            the given year
     * @param month
     *            the given month
     * @param date
     *            the given date
     * @param hourOfDay
     *            the given hour of day
     * @param minute
     *            the given minute
     * @param second
     *            the given second
     * @return the created <code>java.util.Date</code>.
     */
    public static Date createDate(int year, int month, int date, int hourOfDay, int minute, int second) {
        Calendar cal = Calendar.getInstance();
        cal.set(year, (month - 1), date, hourOfDay, minute, second);

        return new Date(cal.getTimeInMillis());
    }
}

Related

1. getEasterDay(int year)
2. getSundayOfEaster(final int year)