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/*
* Copyright (c) 2010 The University of Reading
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University of Reading, nor the names of the
* authors or contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 uk.ac.rdg.resc.edal.time;
import org.joda.time.DateTimeField;
import org.joda.time.DateTimeFieldType;
import org.joda.time.DateTimeZone;
import org.joda.time.DurationField;
import org.joda.time.DurationFieldType;
import org.joda.time.field.PreciseDurationField;
/**
* A Chronology in which each year has exactly 360 days of 12 equal months
* ({@literal i.e.} each month has exactly 30 days). This calendar system is
* used in many climate simulations. There are no leap years.
* In this Chronology, a millisecond instant of zero corresponds with
* 1970-01-01T00:00:00.000Z and a year has a fixed number of milliseconds
* (1000*60*60*24*360).
* There is no concept of an era in this calendar, so all durations and fields
* relating to this concept are not supported. Additionally, the concept of a
* "weekyear" (the year that "owns" a given week) is not implemented.
* Instances of this class can only be created in {@link DateTimeZone#UTC}.
* (Support for time zones makes little sense in this chronology).
* Instances of this class are immutable.
* @author Jon Blower
* @see "http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.4/cf-conventions.html#calendar"
*/
public final class ThreeSixtyDayChronology extends FixedYearLengthChronology {
///// DURATIONS /////
/** 30 days in every month */
private final DurationField monthDuration =
new PreciseDurationField(DurationFieldType.months(), 30 * this.days().getUnitMillis());
private final DateTimeField dayOfMonth =
new OneBasedPreciseDateTimeField(DateTimeFieldType.dayOfMonth(), this.days(), this.monthDuration);
private final DateTimeField monthOfYear =
new OneBasedPreciseDateTimeField(DateTimeFieldType.monthOfYear(), this.monthDuration, this.years());
///// CONSTRUCTORS AND FACTORIES /////
private static final ThreeSixtyDayChronology INSTANCE_UTC = new ThreeSixtyDayChronology();
/** Private constructor to prevent direct instantiation */
private ThreeSixtyDayChronology() {
super(360);
}
/** Gets an instance of this Chronology in the UTC time zone */
public static ThreeSixtyDayChronology getInstanceUTC() {
return INSTANCE_UTC;
}
///// DURATION ACCESSORS /////
/** Each month has exactly 30 days */
@Override
public DurationField months() { return this.monthDuration; }
///// DATE-TIME FIELD ACCESSORS /////
@Override
public DateTimeField dayOfMonth() { return this.dayOfMonth; }
@Override
public DateTimeField monthOfYear() { return this.monthOfYear; }
@Override
public String toString() {
return "360-day Chronology in UTC";
}
}