DateUtil.java Source code

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Here is the source code for DateUtil.java

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/*
 * Funambol is a mobile platform developed by Funambol, Inc. 
 * Copyright (C) 2003 - 2007 Funambol, Inc.
 * 
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License version 3 as published by
 * the Free Software Foundation with the addition of the following permission 
 * added to Section 15 as permitted in Section 7(a): FOR ANY PART OF THE COVERED
 * WORK IN WHICH THE COPYRIGHT IS OWNED BY FUNAMBOL, FUNAMBOL DISCLAIMS THE 
 * WARRANTY OF NON INFRINGEMENT  OF THIRD PARTY RIGHTS.
 * 
 * This program 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 Affero General Public License 
 * along with this program; if not, see http://www.gnu.org/licenses or write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA.
 * 
 * You can contact Funambol, Inc. headquarters at 643 Bair Island Road, Suite 
 * 305, Redwood City, CA 94063, USA, or at email address info@funambol.com.
 * 
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU Affero General Public License version 3.
 * 
 * In accordance with Section 7(b) of the GNU Affero General Public License
 * version 3, these Appropriate Legal Notices must retain the display of the
 * "Powered by Funambol" logo. If the display of the logo is not reasonably 
 * feasible for technical reasons, the Appropriate Legal Notices must display
 * the words "Powered by Funambol".
 */

import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

/**
 * Utility class for date manipulation.
 * This class gives a simple interface for common Date, Calendar and Timezone
 * operations.
 * It is possible to apply subsequent transformations to an initial date, and
 * retrieve the changed Date object at any point.
 *
 */
public class DateUtil {

    //-------------------------------------------------------------- Attributes
    private Calendar cal;

    //------------------------------------------------------------ Constructors

    /** Inizialize a new instance with the current date */
    public DateUtil() {
        this(new Date());
    }

    /** Inizialize a new instance with the given date */
    public DateUtil(Date d) {
        cal = Calendar.getInstance();
        cal.setTime(d);
    }

    //---------------------------------------------------------- Public methods

    /** Set a new time */
    public void setTime(Date d) {
        cal.setTime(d);
    }

    /** Get the current time */
    public Date getTime() {
        return cal.getTime();
    }

    /** Get the current TimeZone */
    public String getTZ() {
        return cal.getTimeZone().getID();
    }

    /**
     * Convert the time to the midnight of the currently set date.
     * The internal date is changed after this call.
     *
     * @return a reference to this DateUtil, for concatenation.
     */
    public DateUtil toMidnight() {

        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MILLISECOND, 0);

        return this;
    }

    /**
     * Make the date go back of the specified amount of days
     * The internal date is changed after this call.
     *
     * @return a reference to this DateUtil, for concatenation.
     */
    public DateUtil removeDays(int days) {

        Date d = cal.getTime();
        long time = d.getTime();
        time -= days * 24 * 3600 * 1000;
        d.setTime(time);
        cal.setTime(d);

        return this;
    }

    /**
     * Make the date go forward of the specified amount of minutes
     * The internal date is changed after this call.
     *
     * @return a reference to this DateUtil, for concatenation.
     */
    public DateUtil addMinutes(int minutes) {
        Date d = cal.getTime();
        long time = d.getTime();
        time += minutes * 60 * 1000;
        d.setTime(time);
        cal.setTime(d);

        return this;
    }

    /**
     * Convert the date to GMT. The internal date is changed
     *
     * @return a reference to this DateUtil, for concatenation.
     */
    public DateUtil toGMT() {
        return toTZ("GMT");
    }

    /**
     * Convert the date to the given timezone. The internal date is changed.
     *
     * @param tz The name of the timezone to set
     *
     * @return a reference to this DateUtil, for concatenation.
     */
    public DateUtil toTZ(String tz) {
        cal.setTimeZone(TimeZone.getTimeZone(tz));

        return this;
    }

    /**
     * Get the days passed from the specified date up to the date provided 
     * in the constructor
     *
     * @param date The starting date
     *
     * @return number of days within date used in constructor and the provided
     * date
     */
    public int getDaysSince(Date date) {
        long millisecs = date.getTime();
        Date d = cal.getTime();
        long time = d.getTime();
        long daysMillisecs = time - millisecs;
        int days = (int) ((((daysMillisecs / 1000) / 60) / 60) / 24);
        return days;
    }

    /**
     * Utility method wrapping Calendar.after method
     * Compares the date field parameter with the date provided with the constructor
     * answering the question: date from constructor is after the given param date ?
     *
     * @param date The date to be used for comparison
     *
     * @return true if date from constructor is after given param date
     */
    public boolean isAfter(Date date) {
        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(date);
        return cal.after(cal2);
    }
}