Re: a question about factory method

Thank you all for replies.

Can you elaborate a little more about
 Its getInstance() methods usually return a GregorianCalendar instance,
but could (if Locales and so on were set up) return an instance of
MayanCalendar or JulianCalendar or BabylonianCalendar or whatever:
Classes whose names, whose very existence, might not have been known
when the calling code was written.

My guess is something like below. Is that correct? Thank you very much.

public class Calendar {

  /**
  * Static factory method returns an object of this class or subclass. for choice: 1 for GregorianCalendar, 2 for MayanCalendar , 3 for JulianCalendar
  */
  public static Calendar getInstance(Date aDate, int choice) {
    if(choice==1){
      ... //return a GregorianCalendar object
    }
    else if(choice==2) {
      ... //return a MayanCalendar object
    }
    else if(choice==3) {
      ... //return a JulianCalendar object
    }
    else {
      return null;
    }
   
  }

....
}

How can I make it return MayanCalendar or JulianCalendar?