Java TimeZone Create getTimeZone(final Calendar cal)

Description

Returns the time zone designator in a ISO6601-compliant format from the given Calendar value.

License

Open Source License

Parameter

Parameter	Description
cal	The Calendar to be formatted.

Return

The time zone designator from the given Calendar.

Declaration

public static String getTimeZone(final Calendar cal) 

Method Source Code

//package com.java2s;
/*/* w  w w.  ja  v  a2s  .co  m*/
 * Copyright (C) 2007 ETH Zurich
 *
 * This file is part of Fosstrak (www.fosstrak.org).
 *
 * Fosstrak is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software Foundation.
 *
 * Fosstrak 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 Fosstrak; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

import java.text.DecimalFormat;

import java.util.Calendar;
import java.util.GregorianCalendar;

import java.util.TimeZone;

public class Main {
    /**
     * Miscellaneous numeric formats used in formatting.
     */
    public static final DecimalFormat XX_FORMAT = new DecimalFormat("00");
    public static final DecimalFormat XXX_FORMAT = new DecimalFormat("000");
    public static final DecimalFormat XXXX_FORMAT = new DecimalFormat("0000");

    /**
     * Returns the time zone designator in a ISO6601-compliant format from the
     * given <code>Calendar</code> value.
     * 
     * @param cal
     *            The Calendar to be formatted.
     * @return The time zone designator from the given Calendar.
     */
    public static String getTimeZone(final Calendar cal) {
        StringBuilder buf = new StringBuilder();
        TimeZone tz = cal.getTimeZone();
        // determine offset of timezone from UTC (incl. daylight saving)
        int offset = tz.getOffset(cal.getTimeInMillis());
        int hours = Math.abs((offset / (60 * 1000)) / 60);
        int minutes = Math.abs((offset / (60 * 1000)) % 60);
        buf.append(offset < 0 ? '-' : '+');
        buf.append(XX_FORMAT.format(hours));
        buf.append(':');
        buf.append(XX_FORMAT.format(minutes));
        return buf.toString();
    }

    /**
     * Formats a <code>Calendar</code> value into an ISO8601-compliant date/time
     * string.
     * 
     * @param cal
     *            The time value to be formatted into a date/time string.
     * @return The formatted date/time string.
     */
    public static String format(final Calendar cal) {
        if (cal == null) {
            throw new IllegalArgumentException("argument can not be null");
        }

        // determine era and adjust year if necessary
        int year = cal.get(Calendar.YEAR);
        if (cal.isSet(Calendar.ERA) && cal.get(Calendar.ERA) == GregorianCalendar.BC) {
            /**
             * calculate year using astronomical system: year n BCE =>
             * astronomical year -n + 1
             */
            year = 0 - year + 1;
        }

        /**
         * the format of the date/time string is: YYYY-MM-DDThh:mm:ss.SSSTZD
         * note that we cannot use java.text.SimpleDateFormat for formatting
         * because it can't handle years <= 0 and TZD's
         */
        StringBuilder buf = new StringBuilder();
        // year ([-]YYYY)
        buf.append(XXXX_FORMAT.format(year));
        buf.append('-');
        // month (MM)
        buf.append(XX_FORMAT.format(cal.get(Calendar.MONTH) + 1));
        buf.append('-');
        // day (DD)
        buf.append(XX_FORMAT.format(cal.get(Calendar.DAY_OF_MONTH)));
        buf.append('T');
        // hour (hh)
        buf.append(XX_FORMAT.format(cal.get(Calendar.HOUR_OF_DAY)));
        buf.append(':');
        // minute (mm)
        buf.append(XX_FORMAT.format(cal.get(Calendar.MINUTE)));
        buf.append(':');
        // second (ss)
        buf.append(XX_FORMAT.format(cal.get(Calendar.SECOND)));
        buf.append('.');
        // millisecond (SSS)
        buf.append(XXX_FORMAT.format(cal.get(Calendar.MILLISECOND)));
        // time zone designator (+/-hh:mm)
        buf.append(getTimeZone(cal));
        return buf.toString();
    }
}

Related

1. getTimeZone()
2. getTimeZone()
3. getTimeZone()
4. getTimeZone()
5. getTimeZone(Date date)
6. getTimeZone(final String id)
7. getTimeZone(final String tzId)
8. getTimeZone(int rawoffset)
9. getTimeZone(String id)