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Jodd Core tools and utilities, including type converters, JDateTime, cache etc.

There is a newer version: 5.3.0

// Copyright (c) 2003-2014, Jodd Team (jodd.org). All Rights Reserved.

package jodd.datetime;

import java.util.TimeZone;

/**
 * Misc timezone utilities.
 */
public class TimeZoneUtil {

	/**
	 * Returns raw offset difference in milliseconds.
	 */
	public static int getRawOffsetDifference(TimeZone from, TimeZone to) {
		int offsetBefore = from.getRawOffset();
		int offsetAfter = to.getRawOffset();
		return offsetAfter - offsetBefore;
	}

	/**
	 * Returns offset difference  in milliseconds for given time.
	 */
	public static int getOffsetDifference(long now, TimeZone from, TimeZone to) {
		int offsetBefore = from.getOffset(now);
		int offsetAfter = to.getOffset(now);
		return offsetAfter - offsetBefore;
	}

	/**
	 * Get offset difference in milliseconds for given jdatetime.
	 */
	public static int getOffset(JDateTime jdt, TimeZone tz) {
		return tz.getOffset(
				jdt.getEra(),
				jdt.getYear(),
				jdt.getMonth() - 1,
				jdt.getDay(),
				TimeUtil.toCalendarDayOfWeek(jdt.getDayOfWeek()),
				jdt.getMillisOfDay()
		);
	}

	public static int getOffsetDifference(JDateTime jdt, TimeZone from, TimeZone to) {
		int offsetBefore = getOffset(jdt, from);
		int offsetAfter = getOffset(jdt, to);
		return offsetAfter - offsetBefore;
	}
}