java - 为什么在我的java change/cashier程序中它总是四舍五入到2美分？

我已经尝试了多种方法，例如math.Round，并使它们加倍和整数，但我不知道为什么以及在哪舍入到2美分。当我购买32.27并用36支付时，答案是3美元2季度2角钱2美分。
这是我的代码：

import java.util.Scanner;

public class Change {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);


        System.out.print("Purchase: ");
        double purchase = input.nextDouble();
        System.out.print("Payment: ");
        double amountGiven = input.nextDouble();

        int remainingAmount = (int) ((amountGiven - purchase) * 100);


        int numOfDollars = remainingAmount / 100;
        remainingAmount = remainingAmount % 100;

        int numOfQuarters = remainingAmount / 25;
        remainingAmount = remainingAmount % 25;

        int numOfDimes = remainingAmount / 10;
        remainingAmount = remainingAmount % 10;

        int numOfPennies = remainingAmount;

        System.out.println("Given $ " + amountGiven + " for a purchase of $ " +
                purchase + " we need " + numOfDollars + " dollars " + numOfQuarters +
                " quarters " + numOfDimes + " dimes " +
                numOfPennies + " cents ");
    }
}

最佳答案

如果运行此代码，您将看到问题出在哪里：

final double purchase = 32.27;
System.out.println("Purchase: " + new BigDecimal(purchase));
final double diff = 36 - purchase;
System.out.println("Difference: " + new BigDecimal(diff));
System.out.println("Cent difference: " + (int)(100*diff));

输出将是

Purchase: 32.27000000000000312638803734444081783294677734375
Difference: 3.72999999999999687361196265555918216705322265625
Cent difference: 372

因此，您可以立即发现问题的根源：十进制值32.27由最接近的double值表示，该值稍大一些。差异则稍小一些，在截断后下降了整分。

课程：不要将输入解析为double，而是解析为into a BigDecimal。

关于java - 为什么在我的java change/cashier程序中它总是四舍五入到2美分？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/21630855/