PracticalAstronomy_GDtoJD.java

public class ShowJulianDay
{
  // arguments are passed using the text field below this editor
  public static void main(String[] args)
  {
    PracticalAstronomy astro = new PracticalAstronomy(2009,6,19,18,0,0);
    System.out.print(astro.getJulianDay());
  }
}

public class PracticalAstronomy
{
  private int year;
  private int month;
  private int day;
  private int hour;
  private int minute;
  private int second;
  public PracticalAstronomy(int year,int month,int day,int hour,int minute,int second)
  {
    this.year = year;
    this.month = month;
    this.day = day;
    this.hour = hour;
    this.minute = minute;
    this.second = second;
  }
  public double getJulianDay()
  {
    boolean julian = true;
    if (year < 1582 || (year == 1582 && month <= 10) || (year == 1582 && month == 10 && day < 15)) julian = false;
    int D = day;
    int M = month;
    int Y = year;
    if (M < 3)
    {
      Y--;
      M += 12;
    }
    int A = Y / 100;
    int B = julian ? 2 - A + A / 4 : 0;
    int C = Y < 0 ? (int)((365.25 * Y) - 0.75) : (int)(365.25 * Y);
    int F = (int)(30.6001 * (M + 1));

    double dayFraction = (hour + (minute + (second / 60.0)) / 60.0) / 24.0;
    double jd =  B + C + F + D + dayFraction + 1720994.5;
    
    return jd;
  }
}