uk.ac.rdg.resc.edal.time.FixedYearVariableMonthChronology Maven / Gradle / Ivy
The newest version!
/*
* 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.Chronology;
import org.joda.time.DateTimeField;
import org.joda.time.DurationField;
/**
* A {@link Chronology} in which each year has the same number of days but
* the lengths of the months may be different. May be useful for climate and
* palaeoclimate calendars.
* 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.
* 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"
* @author Jon
*/
public class FixedYearVariableMonthChronology extends FixedYearLengthChronology {
private final int[] monthLengths;
private final DateTimeField dayOfMonth;
private final DateTimeField monthOfYear;
private final DurationField monthDuration;
/**
* @param monthLengths The number of days in each month
* @throws NullPointerException if monthLengths is null
* @throws IllegalArgumentException if monthLengths is empty or contains
* zero or negative values.
*/
public FixedYearVariableMonthChronology(int[] monthLengths) {
super(sumArray(monthLengths));
this.monthLengths = monthLengths.clone(); // defensive copy
this.dayOfMonth = new DayOfMonthOfFixedYearDateTimeField(this);
this.monthOfYear = new MonthOfFixedYearDateTimeField(this);
this.monthDuration = this.monthOfYear.getDurationField();
}
/**
* Calculates the sum of the values in the given array.
* @throws NullPointerException if arr is null
* @throws IllegalArgumentException if arr is empty or contains
* zero or negative values.
*/
private static int sumArray(int[] arr) {
if (arr == null) throw new NullPointerException("null array");
if (arr.length == 0) throw new IllegalArgumentException("Zero-length array");
int sum = 0;
for (int i = 0; i < arr.length; i++) {
if (arr[i] <= 0) {
throw new IllegalArgumentException("All array values must be > 0");
}
sum += arr[i];
}
return sum;
}
@Override
public final DateTimeField dayOfMonth() {
return this.dayOfMonth;
}
@Override
public final DateTimeField monthOfYear() {
return this.monthOfYear;
}
@Override
public final DurationField months() {
return this.monthDuration;
}
/**
* Gets the length of each month in days. Returns a new array with each
* invocation to maintain integrity of internal data.
* @todo return an immutable List
*/
public int[] getMonthLengths() {
return this.monthLengths.clone(); // Defensive copy
}
/** Gets the average number of milliseconds in each month */
public long getAverageMillisInMonth() {
return this.years().getUnitMillis() / this.monthLengths.length;
}
@Override
public String toString() {
return "Custom calendar: fixed year length, variable month length";
}
}