工厂设计模式

interface A
{public void fintr();
}
class B implements A
{public void fintr(){
   System.out.println("666");
   }
}
class C implements A
{public void fintr(){
    System.out.println("777");
    }
}
class D
{public static A getInfo(String className){
    if ("SSS".equals(className))
    {
        return new B();
    }else if ("aa".equals(className))
    {return new C();
    }
    
    
    return null;
  }
}
public class vvv{
    public static void main(String args[]){
    A a= D.getInfo(args[0]);
      if (a != null)
    {
    a.fintr();
    }
    }
}