Mis omadused on iseloomulikud Factory disainimustrile?

import java.util.List;
import java.util.ArrayList;
class Pet {
  private static List<Pet> pets = new ArrayList<Pet>();
  /*
  Some other stuff...
  */
  private Pet() {}
  public static Pet getPet() {
    if (pets.size() == 10) {
      return null;
    }
    Pet p = new Pet();
    pets.add(p);
    return p;
  }
}