Java 特定客户类型

Question

我想制作一个代码，其中只有客户“R”、“C”和“T”可以进行小计。每当我输入另一个字母(即“S”、“L”、“A”等)时，我希望输出是无效条目。但是，当我输入不是 R、C 或 T 的字母时，系统仍会要求我输入小计。一如既往的帮助。谢谢。代码如下。

======================

    import java.text.NumberFormat;
    import java.util.Scanner;

    public class ValidatedInvoiceApp
    {

        public static void main(String[] args)
        {

        Scanner sc = new Scanner(System.in);
        String choice = "y";

        while (!choice.equalsIgnoreCase("n"))
        {
        // get the input from the user
        System.out.print("Enter customer type (r/c/t): ");
        String customerType = sc.next();
        System.out.print("Enter subtotal: ");
        double subtotal = sc.nextDouble();

        // call the DiscountPercent method
        double discountPercent = getDiscountPercent(
        customerType,subtotal);

        // calculate the discount amount and total
        double discountAmount = subtotal * discountPercent;
        double total = subtotal - discountAmount;

        // format and display the results
        NumberFormat currency = NumberFormat.getCurrencyInstance();
        NumberFormat percent = NumberFormat.getPercentInstance();
        System.out.println(
        "Discount percent: " + percent.format(discountPercent) + "\n" +
        "Discount amount: " + currency.format(discountAmount) + "\n" +
        "Total: " + currency.format(total) + "\n");

        // see if the user wants to continue
        System.out.print("Continue? (y/n): ");
        choice = sc.next();
        System.out.println();
        }
        }
        private static double getDiscountPercent(String customerType,double subtotal)
        {

        double discountPercent = 0;

            if (customerType.equalsIgnoreCase("R"))
        {
            if (subtotal < 100)
                discountPercent = 0;
            else if (subtotal >= 100 && subtotal < 250)
                discountPercent = .1;
            else if (subtotal >= 250 && subtotal < 500)
                 discountPercent = .25;
            else
                discountPercent = .30;
            }
            else if (customerType.equalsIgnoreCase("C"))
            {
                discountPercent = .20;
            }
            else if (customerType.equalsIgnoreCase("T"))
            {
            if (subtotal < 500)
                discountPercent = .40;
            else if (subtotal >= 500)
                discountPercent = .50;
            }
            else

                {
                    System.out.println("Error! Invalid Customer Type.  Please Try Again. \n");
                    sc.nextLine();
                }
        return discountPercent;
    }

    private static class sc {

        private static void nextLine() {
            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
        }

        public sc() {
        }
    }
}

Answer 1

您不对输入进行任何类型的检查。

System.out.print("Enter customer type (r/c/t): ");
String customerType = sc.next();
System.out.print("Enter subtotal: ");
double subtotal = sc.nextDouble();

你应该使用 do-while (或者如果你想要其他行为则使用其他东西)

String customerType;
do
{
    System.out.print("Enter customer type (r/c/t): ");
    customerType = sc.next();
}
while (!customerType.equalsIgnoreCase("r") && !customerType.equalsIgnoreCase("c") && !customerType.equalsIgnoreCase("t"));

使用此代码，直到他写入 r、c 或 t 为止，系统会要求他再次插入。

无论如何，您应该考虑使用 char 而不是 String。