한빛미디어

class  GoodsStock{
        String goodsCode;
        int stockNum;
        
        void addStock(int amount){
                stockNum += amount;
        }

        int subtractStock(int amount){
                if(stockNum < amount)
                        return 0;
                stockNum -= amount;
                return amount;
        }
}


여기서 메소드 addStock은 왜 void이고, 메소드 subtractStock는 왜 int 인가요?