Java,项目商店折扣数学错误

Question

该程序旨在充当商店,其中输入数字以用于相应的项目和数量.问题在于,如果您需要三个或更多项目,您将获得购买的10%折扣,并且应截断任何小数(保持在int数据类型的整数范围内).程序将运行,但不计算折扣,并且程序将运行时始终显示为0.看看这个!

int item, longsword, shortsword, warhammer, ring, potion, itemcost, quantity, discount, totalcost, finalcost;

    System.out.print("Item Number: ");
    item = keyboard.nextInt();

    final int LONGSWORD = 120;
    final int SHORTSWORD = 90;
    final int WARHAMMER = 80;
    final int RING = 150;
    final int POTION = 10;

    itemcost = 0;

    if (item == 1)
    {
        itemcost = LONGSWORD;
    }

    if (item == 2)
    {
        itemcost = SHORTSWORD;
    }   

    if (item == 3)
    {
        itemcost = WARHAMMER;
    }   

    if (item == 4)
    {
        itemcost = RING;
    }

    if (item == 5)
    {
        itemcost = POTION;
    }

    System.out.print("Quantity of Item: ");
    quantity = keyboard.nextInt();  

    totalcost = itemcost * quantity;

    System.out.println("Total Cost: " + totalcost);

    if (quantity >= 3)
    {
        discount = totalcost * (1/10);
    }

    else
    {
        discount = 0;
    }

    System.out.println("Discount: " + discount);

Answer 1

您遇到了如此常见的整数除法问题.

discount = totalcost * (1/10);

1/10是0,所以discount将是0.使用此代替:

discount = (int) (totalcost * (0.1));