Class JulianDayHelper

java.lang.Object

eu.fastipletonis.astro.temporal.JulianDayHelper

public class JulianDayHelper
extends Object

Helper for calculating the astronomical Julian day.

The standard Java implementation for JulianFields.JULIAN_DAY only implements long results. Astronomical calculations often require a Julian Day able to handle the time of the day as well.

Please notice that this implementation completely ignores the time zone. The user should ensure the use of the appropriate time frame.

The Julian day is calculated according to Meeus' algorithm explained in Chapter 7.

Method Summary

Modifier and Type	Method	Description
static BigDecimal	getBigDecimalFrom(TemporalAccessor temporal)	Returns the Julian day from the given temporal accessor as a BigDecimal value.
static double	getDoubleFrom(TemporalAccessor temporal)	Returns the Julian day from the given temporal accessor as a double floating-point value.
static LocalDateTime	getLocalDateTimeFrom(double jd)	Converts a Julian Day into a calendar date, storing the result in a LocalDateTime object.
static LocalDateTime	getLocalDateTimeFrom(BigDecimal jd)	Converts a Julian Day into a calendar date, storing the result in a LocalDateTime object.
static boolean	isSupported(TemporalAccessor temporal)	Checks if the given temporal accessor can be used to extract a Julian day.

Methods inherited from class Object

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

Method Details

isSupported

public static boolean isSupported(TemporalAccessor temporal)

Checks if the given temporal accessor can be used to extract a Julian day.

The following fields are checked:

• ChronoField.YEAR
• ChronoField.MONTH_OF_YEAR
• ChronoField.DAY_OF_MONTH
• ChronoField.NANO_OF_DAY

Both LocalDateTime and ZonedDateTime satisfy these prerequisites.

Parameters:

temporal - the temporal accessor to be checked

Returns:

true if all the required fields are supported

See Also:

• Information on specific fields.

getBigDecimalFrom

public static BigDecimal getBigDecimalFrom(TemporalAccessor temporal)

Returns the Julian day from the given temporal accessor as a BigDecimal value.

The temporal accessor must support the following fields:

• ChronoField.YEAR
• ChronoField.MONTH_OF_YEAR
• ChronoField.DAY_OF_MONTH
• ChronoField.NANO_OF_DAY

Both LocalDateTime and ZonedDateTime satisfy these prerequisites.

Parameters:

temporal - the temporal accessor

Returns:

the Julian Day as a BigDecimal value

getDoubleFrom

public static double getDoubleFrom(TemporalAccessor temporal)

Returns the Julian day from the given temporal accessor as a double floating-point value.

The temporal accessor must support the following fields:

• ChronoField.YEAR
• ChronoField.MONTH_OF_YEAR
• ChronoField.DAY_OF_MONTH
• ChronoField.NANO_OF_DAY

Both LocalDateTime and ZonedDateTime satisfy these prerequisites.

Parameters:

temporal - the temporal accessor

Returns:

the Julian Day as a value of type double

getLocalDateTimeFrom

public static LocalDateTime getLocalDateTimeFrom(double jd)

Converts a Julian Day into a calendar date, storing the result in a LocalDateTime object.

The conversion uses the procedure described in Chapter 7 to convert a Julian Day back to a calendar date.

Parameters:

jd - the Julian Day to convert.

Returns:

a LocalDatTime object representing the Julian Day

Throws:

DateTimeException - if a negative Julian Day is passed as an argument

getLocalDateTimeFrom

public static LocalDateTime getLocalDateTimeFrom(BigDecimal jd)

Converts a Julian Day into a calendar date, storing the result in a LocalDateTime object.

The conversion uses the procedure described in Chapter 7 to convert a Julian Day back to a calendar date.

Parameters:

jd - the Julian Day to convert.

Returns:

a LocalDateTime object representing the Julian Day

Throws:

DateTimeException - if a negative Julian Day is passed as an argument