Java TimeZone To createTimeZoneFromDouble(double timeZoneOffsetInHours)

Description

create Time Zone From Double

License

Open Source License

Declaration

public static TimeZone createTimeZoneFromDouble(double timeZoneOffsetInHours) 

Method Source Code

//package com.java2s;
/* MOD_V2.0//from   w w  w  .  j av  a  2  s . com
 * Copyright (c) 2012 OpenDA Association
 * All rights reserved.
 *
 * This file is part of OpenDA.
 *
 * OpenDA is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * OpenDA 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with OpenDA.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.*;

public class Main {
    private static final long hoursToMillis = 1000 * 60 * 60;
    private static final long minutesToMillis = 1000 * 60;

    public static TimeZone createTimeZoneFromDouble(double timeZoneOffsetInHours) {
        long offsetInMinutes = Math.round(timeZoneOffsetInHours * 60d);
        if (offsetInMinutes == 0) {
            return TimeZone.getTimeZone("GMT");
        }
        return TimeZone.getTimeZone(getTimeZoneString(offsetInMinutes * minutesToMillis));
    }

    /**
     * @param timeZoneOffsetMillis has to be between -12 and +12 hours and has to be rounded on minutes.
     * @return String timeZone.
     */
    public static String getTimeZoneString(long timeZoneOffsetMillis) {
        if (timeZoneOffsetMillis % minutesToMillis != 0) {
            throw new IllegalArgumentException("timeZoneOffsetMillis % minutesToMillis != 0");
        }

        if (Math.abs(timeZoneOffsetMillis) > 12 * hoursToMillis) {
            throw new IllegalArgumentException("Math.abs(timeZoneOffsetMillis) > 12 * hoursToMillis");
        }

        char sign = timeZoneOffsetMillis >= 0 ? '+' : '-';
        long unsignedTimeZoneOffsetMillis = Math.abs(timeZoneOffsetMillis);
        long minuteMillis = unsignedTimeZoneOffsetMillis % hoursToMillis;
        long hourMillis = unsignedTimeZoneOffsetMillis - minuteMillis;

        int minutes = (int) (minuteMillis / minutesToMillis);
        int hours = (int) (hourMillis / hoursToMillis);

        if (minutes == 0) {
            return "GMT" + sign + hours;
        }

        if (minutes <= 9) {
            return "GMT" + sign + hours + ":0" + minutes;
        } else {
            return "GMT" + sign + hours + ':' + minutes;
        }
    }
}

Related

1. extractTimeZone(String strdate, Date thedate)
2. parseTimeZoneString(String timeZoneString)
3. setTimeZone(String name)
4. timeZoneToCode(TimeZone tz)