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DateConverter

com.bahmanm.persianutils.DateConverter provides high-precision bidirectional conversion between the Gregorian calendar and the Persian (Solar Hijri) calendar.

The conversion logic is a Scala implementation based on the 3,000-year astronomical algorithm described in The Persian calendar for 3000 years by Kazimierz M. Borkowski.

Key Concepts

  • Indexing: Months and days are 1-indexed. For example, in the Persian calendar Farvardin is month 1 and Esfand is month 12. In the Gregorian calendar, January is 1 and December is 12.
  • Immutability: Both PersianDate and GregorianDate are immutable case classes.
  • String Parsing: Persian dates formatted as YYYY/MM/DD (e.g. "1392/09/24") can directly initialise a PersianDate.

Usage in Scala

import com.bahmanm.persianutils.DateConverter._

// Convert Gregorian to Persian
val gDate1 = GregorianDate(2013, 12, 11)
val pDate1 = gregorianToPersian(gDate1)
println(pDate1) // 1392/9/20

// Convert Persian to Gregorian
val pDate2 = PersianDate(1392, 1, 1)
val gDate2 = persianToGregorian(pDate2)
println(gDate2) // 2013/3/21

// Initialise from formatted string
val pDate3 = PersianDate("1392/09/24")
val gDate3 = persianToGregorian(pDate3)
println(gDate3) // 2013/12/15

// Legacy Java Date interoperability
val legacyDate = java.util.Calendar.getInstance().getTime()
val sDate = SimpleDate(legacyDate)
val pDate4 = gregorianToPersian(sDate)

Usage in Java

DateConverter exposes static helper methods for straightforward Java interop:

import com.bahmanm.persianutils.DateConverter;
import com.bahmanm.persianutils.GregorianDate;
import com.bahmanm.persianutils.PersianDate;

public class CalendarExample {
    public static void main(String[] args) {
        // Persian to Gregorian
        PersianDate pd = new PersianDate(1392, 11, 11);
        GregorianDate gd = DateConverter.persianToGregorian(pd);
        System.out.println(gd);

        // Gregorian to Persian
        GregorianDate gd2 = new GregorianDate(2014, 2, 4);
        PersianDate pd2 = DateConverter.gregorianToPersian(gd2);
        System.out.println(pd2);
    }
}