com.github.lespaul361.commons.commonroutines.utilities.DateTime Maven / Gradle / Ivy

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/*
 * Copyright (C) 2019 Charles Hamilton
 *
 * 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 .
 */
package com.github.lespaul361.commons.commonroutines.utilities;

import java.util.Calendar;
import java.util.TimeZone;

/**
 * Class with helper methods for date and time
 * 
 * @author Charles Hamilton
 */
public class DateTime {

    /**
     * Converts the time from one time zone to another
     * 
     * @param fromCalendar
     *            the original date and time
     * @param to
     *            the time zone to convert it to
     * @return Calendar
     */
    public static Calendar convertTimeZone(Calendar fromCalendar, TimeZone to) {
	TimeZone fromTimeZone = fromCalendar.getTimeZone();
	TimeZone toTimeZone = to;

	fromCalendar.setTimeZone(fromTimeZone);
	fromCalendar.add(Calendar.MILLISECOND, fromTimeZone.getRawOffset() * -1);
	if (fromTimeZone.inDaylightTime(fromCalendar.getTime())) {
	    fromCalendar.add(Calendar.MILLISECOND, fromCalendar.getTimeZone().getDSTSavings() * -1);
	}

	fromCalendar.add(Calendar.MILLISECOND, toTimeZone.getRawOffset());
	if (toTimeZone.inDaylightTime(fromCalendar.getTime())) {
	    fromCalendar.add(Calendar.MILLISECOND, toTimeZone.getDSTSavings());
	}

	System.out.println(fromCalendar.getTime());
	return fromCalendar;
    }
}