handy tool for working with time strings

DateHelper.java

package com.ifit.android.sdk.util;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;

public class DateHelper {

	public static String iso8601DateFormat;
	private static TimeZone mUTCTimeZone;

	public DateHelper() {
	}

	static {
		iso8601DateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
		mUTCTimeZone = TimeZone.getTimeZone("UTC");
	}

	/*
	 * iso8601Date parameter must be "yyyy-MM-dd HH:mm:ss.SSSZ" formatted date
	 * dates are returned in the UTC time zone time. returns null for parse
	 * exceptions
	 */
	public static Date dateFromISO8601(String iso8601Date) {
		if (iso8601Date == null)
			return null;
		try {
			DateFormat dateFormat = new SimpleDateFormat(iso8601DateFormat,
					Locale.US);
			dateFormat.setTimeZone(mUTCTimeZone);
			return dateFormat.parse(iso8601Date);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}

	/*
	 * takes a date and returns a "yyyy-MM-dd HH:mm:ss.SSSZ" formatted string.
	 * The time zone for this string is UTC. This format must be used when
	 * storing and transferring dates. for local formatted date strings, use
	 * another method
	 */
	public static String iso8601FormattedStringFromDate(Date date) {
		DateFormat dateFormat = new SimpleDateFormat(iso8601DateFormat,
				Locale.US);
		dateFormat.setTimeZone(mUTCTimeZone);
		return dateFormat.format(date);
	}

	public enum TimestampType {
		SecondsSinceEpoc, MillisSinceEpoc
	}

	public static String iso8601FormattedStringFromTimestamp(long timestamp,
			TimestampType timestampType) {
		if (timestampType == TimestampType.SecondsSinceEpoc) {
			timestamp = timestamp * 1000;
		}
		Date date = new Date(timestamp);
		return iso8601FormattedStringFromDate(date);
	}

	public static long getTodayMillis() {
		Calendar c = new GregorianCalendar();
	    c.set(Calendar.HOUR_OF_DAY, 0); //anything 0 - 23
	    c.set(Calendar.MINUTE, 0);
	    c.set(Calendar.SECOND, 0);
        c.set(Calendar.MILLISECOND, 0);
		return c.getTimeInMillis();
	}
}