java - 使用户输入的总数加倍

Question

我无法正确更新总价。我输入书籍 = 12.49 音乐 cd = 14.99 和巧克力棒 = 0.85。发生的情况是 14.99 * .10 正在添加和巧克力棒。它正在删除第一个值 12.49。

public class SalesTax {
public static void main(String[] args) 
{
    // Input items for shopping cart
    HashMap<String, String> cart = new HashMap<String, String>();
    HashMap<String, String> shoppingcart = new HashMap<String, String>();

    // Create a Scanner
    Scanner input = new Scanner(System.in);

    // variables
    char done;
    //boolean goods;
    double totalprice = 0.00;
    double taxprice;

    // Pick items for list.
    do 
    {  
        System.out.print("Please enter an item.");
        String item = input.nextLine();

        System.out.print("Please enter the price for "+ item + ": ");
        String price = input.nextLine(); 

        double price1 = Double.parseDouble(price);
        totalprice += price1;

        //System.out.println(String.format("%.2f",totalprice));
        String price2 = String.valueOf(price1);
        cart.put(item, price2);

        //determine if item will have additional tax
        if (item.contains("music"))
        {
            double newprice = Double.parseDouble(price);
            taxprice = newprice * .10;

            totalprice = (newprice + taxprice);

            //System.out.println(String.format("%.2f",totalprice));
            String newprice2 = String.valueOf(String.format("%.2f", totalprice));
            shoppingcart.put(item,newprice2);
        }
        else if (item.contains("imported"))
        {
            double newprice = Double.parseDouble(price);
            newprice = newprice * .05;

            totalprice += newprice;
            //System.out.println(String.format("%.2f",totalprice));
            String newprice2 = String.valueOf(String.format("%.2f", newprice));
            shoppingcart.put(item, newprice2);
        }
        else if(item.contains("bottle"))
        {
            double newprice = Double.parseDouble(price);
            newprice = newprice * .10;

            totalprice += newprice;
            System.out.println(String.format("%.2f",totalprice));
            String newprice2 = String.valueOf(String.format("%.2f", newprice));
            shoppingcart.put(item, newprice2);
        }
        else 
        {
            shoppingcart.put(item, price);
        }


        System.out.print("Would you like to continue to add items? (Type Y) for Yes and (Type N) for No.");
        done = input.nextLine().charAt(0);
    } while(Character.toUpperCase(done) == 'Y');

   System.out.println("Your cart contains the following at items with tax" + shoppingcart); //+ String.format("%.2f", totalprice));
   System.out.println(String.format("%.2f",totalprice));
}

}

Answer 1

在此代码中:

        if (item.contains("music") == true)
        {
            double newprice = Double.parseDouble(price);
            newprice = newprice * 1.10;

            totalprice += newprice;
            //System.out.println(String.format("%.2f",totalprice));
            String newprice2 = String.valueOf(String.format("%.2f", newprice));
            shoppingcart.put(item,newprice2);
        }

值1.10应该是0.10，因为您已经在上面添加了音乐CD的价格，现在只需添加税即可。使用值 1.10，您将添加 CD 的价格(再次)加上税费。