horstmann.ch03_day3

Class Day

java.lang.Object

horstmann.ch03_day3.Day

public class Day
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
private int	date
private int	julian
private boolean	julianValid
private int	month
private int	year
private boolean	ymdValid

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Day(int aJulian)
	Day(int aYear, int aMonth, int aDate) Constructs a day with a given year, month, and day of the Julian/Gregorian calendar.

Method Summary

Modifier and Type	Method and Description
Day	addDays(int n) Returns a day that is a certain number of days away from this day
int	daysFrom(Day other) Returns the number of days between this day and another day
private void	ensureJulian() Computes the Julian day number of this day if necessary
private void	ensureYmd() Converts this Julian day mumber to a calendar date if necessary.
private static int[]	fromJulian(int j) Converts a Julian day number to a calendar date.
int	getDate() Returns the day of the month of this day
int	getMonth() Returns the month of this day
int	getYear() Returns the year of this day
private static int	toJulian(int year, int month, int date) Computes the Julian day number of the given day day.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

year

private int year

month

private int month

date

private int date

julian

private int julian

ymdValid

private boolean ymdValid

julianValid

private boolean julianValid

Constructor Detail

Day

public Day(int aYear,
           int aMonth,
           int aDate)

Constructs a day with a given year, month, and day of the Julian/Gregorian calendar. The Julian calendar is used for all days before October 15, 1582

Parameters:

aYear - a year != 0

aMonth - a month between 1 and 12

aDate - a date between 1 and 31

Day

private Day(int aJulian)

Method Detail

getYear

public int getYear()

Returns the year of this day

Returns:

the year

getMonth

public int getMonth()

Returns the month of this day

Returns:

the month

getDate

public int getDate()

Returns the day of the month of this day

Returns:

the day of the month

addDays

public Day addDays(int n)

Returns a day that is a certain number of days away from this day

Parameters:

n - the number of days, can be negative

Returns:

a day that is n days away from this one

daysFrom

public int daysFrom(Day other)

Returns the number of days between this day and another day

Parameters:

other - the other day

Returns:

the number of days that this day is away from the other (>0 if this day comes later)

ensureJulian

private void ensureJulian()

Computes the Julian day number of this day if necessary

ensureYmd

private void ensureYmd()

Converts this Julian day mumber to a calendar date if necessary.

toJulian

private static int toJulian(int year,
                            int month,
                            int date)

Computes the Julian day number of the given day day.

Parameters:

year - a year

month - a month

date - a day of the month

Returns:

The Julian day number that begins at noon of the given day Positive year signifies CE, negative year BCE. Remember that the year after 1 BCE is 1 CE. A convenient reference point is that May 23, 1968 noon is Julian day number 2440000. Julian day number 0 is a Monday. This algorithm is from Press et al., Numerical Recipes in C, 2nd ed., Cambridge University Press 1992

fromJulian

private static int[] fromJulian(int j)

Converts a Julian day number to a calendar date. This algorithm is from Press et al., Numerical Recipes in C, 2nd ed., Cambridge University Press 1992

Parameters:

j - the Julian day number

Returns:

an array whose 0 entry is the year, 1 the month, and 2 the day of the month.