DateUtil.java

/*
 * Copyright 2010-2015 Institut Pasteur.
 * 
 * This file is part of Icy.
 * 
 * Icy 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.
 * 
 * Icy 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 Icy. If not, see <http://www.gnu.org/licenses/>.
 */
package icy.util;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

/**
 * Date utilities class.
 * 
 * @author Stephane
 */
public class DateUtil
{
    public static final long DAY_IN_MS = 1000 * 60 * 60 * 24;

    /**
     * Returns elapsed milli second from 01/01/1970 (same as {@link System#currentTimeMillis()})
     */
    public static long getTime()
    {
        return System.currentTimeMillis();
    }

    /**
     * Keep only the day part information from the given time (elapsed milli second from
     * 01/01/1970).
     * 
     * @see System#currentTimeMillis
     */
    public static long keepDay(long time)
    {
        return (time / DAY_IN_MS) * DAY_IN_MS;
    }

    /**
     * Keep only the time information (hour, minute, second and milli second) from the given time
     * (elapsed milli second from 01/01/1970).
     * 
     * @see System#currentTimeMillis
     */
    public static long keepTime(long time)
    {
        return time % DAY_IN_MS;
    }

    /**
     * Return elapsed day from 01/01/1970
     * 
     * @see System#currentTimeMillis
     */
    public static long getDay()
    {
        return getTime() / DAY_IN_MS;
    }

    /**
     * Return current date.
     */
    public static Date now()
    {
        return Calendar.getInstance().getTime();
    }

    /**
     * Return current date (String format).<br>
     * 
     * @param format
     *        define the wanted format.<br>
     *        Ex :<br>
     *        DateUtil.now("dd MMMMM yyyy");<br>
     *        DateUtil.now("yyyyMMdd");<br>
     *        DateUtil.now("MM/dd/yy");<br>
     *        DateUtil.now("yyyy.MM.dd G 'at' hh:mm:ss z");<br>
     *        DateUtil.now("H:mm:ss:SSS");<br>
     *        DateUtil.now("yyyy.MMMMM.dd GGG hh:mm aaa");<br>
     */
    public static String now(String format)
    {
        return new SimpleDateFormat(format).format(now());
    }

    /**
     * Return the specified date in String format.<br>
     * 
     * @param format
     *        define the wanted format.<br>
     *        Ex :<br>
     *        DateUtil.now("dd MMMMM yyyy");<br>
     *        DateUtil.now("yyyyMMdd");<br>
     *        DateUtil.now("MM/dd/yy");<br>
     *        DateUtil.now("yyyy.MM.dd G 'at' hh:mm:ss z");<br>
     *        DateUtil.now("H:mm:ss:SSS");<br>
     *        DateUtil.now("yyyy.MMMMM.dd GGG hh:mm aaa");<br>
     */
    public static String format(String format, Date date)
    {
        return new SimpleDateFormat(format).format(date);
    }
    
    /**
     * Returns given time in ms in in international time String format.
     * 
     * @param valueInMs
     *        : value in milliseconds
     * @return <b>Example:</b> "2:21:18.345" for 2h21mn, "1.543" for 1 second and 543 ms
     */
    public static String getTimeAsString(double valueInMs)
    {
        String result = "";
        double v = valueInMs;

        if (v >= 3600000d)
        {
            result += (int) (v / 3600000d);
            v %= 3600000d;
        }
        if (v >= 60000d)
        {
            if (StringUtil.isEmpty(result)) result += ":";
            result += (int) (v / 60000d);
            v %= 60000d;
        }
        if (v >= 1000d)
        {
            if (StringUtil.isEmpty(result)) result += ":";
            result += (int) (v / 1000d);
            v %= 1000d;
        }
        if (v != 0d)
        {
            if (StringUtil.isEmpty(result)) result += ".";
            result += (int) v;
        }

        return result;
    }
}