/*
* $Id: Dates.java,v 1.6 2006/04/05 10:49:48 fortuna Exp $
*
* Created on 26/06/2005
*
* Copyright (c) 2005, Ben Fortuna
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* o Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* o Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* o Neither the name of Ben Fortuna nor the names of any other contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package net.fortuna.ical4j.util;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.TimeZone;
import net.fortuna.ical4j.model.Date;
import net.fortuna.ical4j.model.DateTime;
import net.fortuna.ical4j.model.parameter.Value;
/**
* Implements a collection of utility methods relevant to date processing.
*
* @author Ben Fortuna
*/
public final class Dates {
public static final long MILLIS_PER_SECOND = 1000;
public static final long MILLIS_PER_MINUTE = 60000;
public static final long MILLIS_PER_HOUR = 3600000;
public static final long MILLIS_PER_DAY = 86400000;
public static final long MILLIS_PER_WEEK = 604800000;
public static final int DAYS_PER_WEEK = 7;
public static final int PRECISION_SECOND = 0;
public static final int PRECISION_DAY = 1;
/**
* Constructor made private to prevent instantiation.
*/
private Dates() {
}
/**
* Returns the absolute week number for the year specified by the
* supplied date. Note that a value of zero (0) is invalid for the
* weekNo parameter and an <code>IllegalArgumentException</code>
* will be thrown.
* @param date
* @param weekNo
* @return
*/
public static int getAbsWeekNo(final java.util.Date date, final int weekNo) {
if (weekNo == 0 || weekNo < -53 || weekNo > 53) {
throw new IllegalArgumentException("Invalid week number [" + weekNo + "]");
}
if (weekNo > 0) {
return weekNo;
}
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int year = cal.get(Calendar.YEAR);
// construct a list of possible week numbers..
List weeks = new ArrayList();
cal.set(Calendar.WEEK_OF_YEAR, 1);
while (cal.get(Calendar.YEAR) == year) {
weeks.add(new Integer(cal.get(Calendar.WEEK_OF_YEAR)));
cal.add(Calendar.WEEK_OF_YEAR, 1);
}
return ((Integer) weeks.get(weeks.size() + weekNo)).intValue();
}
/**
* Returns the absolute year day for the year specified by the
* supplied date. Note that a value of zero (0) is invalid for the
* yearDay parameter and an <code>IllegalArgumentException</code>
* will be thrown.
* @param date
* @param yearDay
* @return
*/
public static int getAbsYearDay(final java.util.Date date, final int yearDay) {
if (yearDay == 0 || yearDay < -366 || yearDay > 366) {
throw new IllegalArgumentException("Invalid year day [" + yearDay + "]");
}
if (yearDay > 0) {
return yearDay;
}
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int year = cal.get(Calendar.YEAR);
// construct a list of possible year days..
List days = new ArrayList();
cal.set(Calendar.DAY_OF_YEAR, 1);
while (cal.get(Calendar.YEAR) == year) {
days.add(new Integer(cal.get(Calendar.DAY_OF_YEAR)));
cal.add(Calendar.DAY_OF_YEAR, 1);
}
return ((Integer) days.get(days.size() + yearDay)).intValue();
}
/**
* Returns the absolute month day for the month specified by the
* supplied date. Note that a value of zero (0) is invalid for the
* monthDay parameter and an <code>IllegalArgumentException</code>
* will be thrown.
* @param date
* @param monthDay
* @return
*/
public static int getAbsMonthDay(final java.util.Date date, final int monthDay) {
if (monthDay == 0 || monthDay < -31 || monthDay > 31) {
throw new IllegalArgumentException("Invalid month day [" + monthDay + "]");
}
if (monthDay > 0) {
return monthDay;
}
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int month = cal.get(Calendar.MONTH);
// construct a list of possible month days..
List days = new ArrayList();
cal.set(Calendar.DAY_OF_MONTH, 1);
while (cal.get(Calendar.MONTH) == month) {
days.add(new Integer(cal.get(Calendar.DAY_OF_MONTH)));
cal.add(Calendar.DAY_OF_MONTH, 1);
}
return ((Integer) days.get(days.size() + monthDay)).intValue();
}
/**
* Returns a new date instance of the specified type. If no type is
* specified a DateTime instance is returned.
* @param date a seed Java date instance
* @param type the type of date instance
* @return an instance of <code>net.fortuna.ical4j.model.Date</code>
*/
public static Date getInstance(final java.util.Date date, final Value type) {
if (Value.DATE.equals(type)) {
return new Date(date);
}
return new DateTime(date);
}
/**
* Returns an instance of <code>java.util.Calendar</code> that is suitably
* initialised for working with the specified date.
* @param date a date instance
* @return a <code>java.util.Calendar</code>
*/
public static Calendar getCalendarInstance(final Date date) {
if (date instanceof DateTime) {
DateTime dateTime = (DateTime) date;
if (dateTime.getTimeZone() != null) {
return Calendar.getInstance(dateTime.getTimeZone());
}
else if (dateTime.isUtc()) {
return Calendar.getInstance(TimeZone.getTimeZone(TimeZones.UTC_ID));
}
}
return Calendar.getInstance(); //TimeZone.getTimeZone(TimeZones.GMT_ID));
}
/**
* Rounds a time value to remove any precision smaller than specified.
* @param time the time value to round
* @return a round time value
*/
public static long round(final long time, final int precision) {
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(time);
if (precision == PRECISION_DAY) {
// return (long) Math.floor(time / (double) Dates.MILLIS_PER_DAY) * Dates.MILLIS_PER_DAY;
cal.set(Calendar.HOUR_OF_DAY, 0);
cal.clear(Calendar.MINUTE);
cal.clear(Calendar.SECOND);
cal.clear(Calendar.MILLISECOND);
}
else if (precision == PRECISION_SECOND) {
// return (long) Math.floor(time / (double) Dates.MILLIS_PER_SECOND) * Dates.MILLIS_PER_SECOND;
cal.clear(Calendar.MILLISECOND);
}
// unrecognised precision..
return cal.getTimeInMillis();
}
}