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JulianFields.JulianDay Property

  • Reference

Definition

Namespace:
Java.Time.Temporal
Assembly:
Mono.Android.dll

Julian Day field.

[Android.Runtime.Register("JULIAN_DAY", ApiSince=26)]
public static Java.Time.Temporal.ITemporalField? JulianDay { get; }
[<Android.Runtime.Register("JULIAN_DAY", ApiSince=26)>]
static member JulianDay : Java.Time.Temporal.ITemporalField

Property Value

ITemporalField
Attributes
RegisterAttribute

Remarks

Julian Day field.

This is an integer-based version of the Julian Day Number. Julian Day is a well-known system that represents the count of whole days since day 0, which is defined to be January 1, 4713 BCE in the Julian calendar, and -4713-11-24 Gregorian. The field has "JulianDay" as 'name', and 'DAYS' as 'baseUnit'. The field always refers to the local date-time, ignoring the offset or zone.

For date-times, 'JULIAN_DAY.getFrom()' assumes the same value from midnight until just before the next midnight. When 'JULIAN_DAY.adjustInto()' is applied to a date-time, the time of day portion remains unaltered. 'JULIAN_DAY.adjustInto()' and 'JULIAN_DAY.getFrom()' only apply to Temporal objects that can be converted into ChronoField#EPOCH_DAY. An UnsupportedTemporalTypeException is thrown for any other type of object.

In the resolving phase of parsing, a date can be created from a Julian Day field. In ResolverStyle#STRICT strict mode and ResolverStyle#SMART smart mode the Julian Day value is validated against the range of valid values. In ResolverStyle#LENIENT lenient mode no validation occurs.

<h4>Astronomical and Scientific Notes</h4> The standard astronomical definition uses a fraction to indicate the time-of-day, where each day is counted from midday to midday. For example, a fraction of 0 represents midday, a fraction of 0.25 represents 18:00, a fraction of 0.5 represents midnight and a fraction of 0.75 represents 06:00.

By contrast, this implementation has no fractional part, and counts days from midnight to midnight. This implementation uses an integer and days starting at midnight. The integer value for the Julian Day Number is the astronomical Julian Day value at midday of the date in question. This amounts to the astronomical Julian Day, rounded to an integer JDN = floor(JD + 0.5).

| ISO date          |  Julian Day Number | Astronomical Julian Day |
             | 1970-01-01T00:00  |         2,440,588  |         2,440,587.5     |
             | 1970-01-01T06:00  |         2,440,588  |         2,440,587.75    |
             | 1970-01-01T12:00  |         2,440,588  |         2,440,588.0     |
             | 1970-01-01T18:00  |         2,440,588  |         2,440,588.25    |
             | 1970-01-02T00:00  |         2,440,589  |         2,440,588.5     |
             | 1970-01-02T06:00  |         2,440,589  |         2,440,588.75    |
             | 1970-01-02T12:00  |         2,440,589  |         2,440,589.0     |

Julian Days are sometimes taken to imply Universal Time or UTC, but this implementation always uses the Julian Day number for the local date, regardless of the offset or time-zone.

Java documentation for java.time.temporal.JulianFields.JULIAN_DAY.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.

Applies to