public boolean equals(Object otherObject) {
   if (otherObject == null) return false;
   else if (getClass() != otherObject.getClass()) return false;
   else {
     DiscountSale otherSale = (DiscountSale) otherObject;
     return (discount == otherSale.getDiscount()
         && getName().equals(otherSale.getName())
         && (getPrice() == otherSale.getPrice()));
   }
 }
 public DiscountSale(DiscountSale originalObject) {
   /** 구현 하시오 * */
   if (originalObject == null) {
     System.out.println("Error: null Sale object.");
     System.exit(0);
   }
   // else
   setName(originalObject.getName());
   setPrice(originalObject.getPrice());
 }
 public DiscountSale(DiscountSale originalObject) {
   super(originalObject.getName(), originalObject.getPrice());
   discount = originalObject.getDiscount();
 }