Question

我对Java很新。我正在做一个程序，根据一个人的婚姻状况计算所得税汇总。除了一个问题，我的程序还可以工作：我的婚姻状况输入验证部分工作不正常。当我输入s，m，M，c和C以外的东西时，该程序应该为此执行输入验证，但是目前，当我输入类似x的东西时，它会跳过总收入和豁免，并吐出税率，欠税和应纳税所得均为0。

编辑：对不起，如果那令人困惑。基本上，如果用户使用无效输入，然后用户输入有效的内容，我想知道如何让它回到switch语句的开头以确定税率任何帮助将不胜感激！

import java.util.Scanner;

public class TaxPrep
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);

        char maritalStatus;
        double grossIncome = 0;
        double numberOfExemptions = 0;
        double taxRate = 0;
        double taxableIncome = 0;
        double taxesOwed = 0;
        String anotherCustomer = "y";

        System.out.print("_ _ _ _ _ ' S  T A X  P R E P A R E R\n\n");

        do{
            System.out.print("Are you (s)ingle, (m)arried, or (c)ohabiting?\n");
            System.out.print("Enter s, m, or c ==> ");
            maritalStatus = sc.next().charAt(0);
            switch (maritalStatus)
            {
                case 's': case 'S':
                    System.out.print("Gross income ==> ");
                    grossIncome = sc.nextDouble();
                    System.out.print("Number of exemptions ==> ");
                    numberOfExemptions = sc.nextInt();
                    taxableIncome = grossIncome - (1000 * numberOfExemptions);
                    taxRate = 20;
                    break;
                case 'm': case 'M':
                    System.out.print("Gross income ==> ");
                    grossIncome = sc.nextDouble();
                    System.out.print("Number of exemptions ==> ");
                    numberOfExemptions = sc.nextInt();
                    taxableIncome = grossIncome - (1000 * numberOfExemptions);
                    taxRate = 25;
                    break;
                case 'c': case 'C': //tax rate for cohabiting depends on taxable income
                    System.out.print("Gross income ==> ");
                    grossIncome = sc.nextDouble();
                    System.out.print("Number of exemptions ==> ");
                    numberOfExemptions = sc.nextInt();
                    taxableIncome = grossIncome - (1000 * numberOfExemptions);
                    if (taxableIncome <= 20_000)
                    {
                        taxRate = 10;
                        break;
                    }
                    else if (taxableIncome <= 50_000)
                    {
                        taxRate = 15;
                        break;
                    }
                    else
                    {
                        taxRate = 30;
                        break;
                    }
                default: //if input for marital status is invalid
                    do{ //continues to ask for valid input until user inputs a valid marital status
                        System.out.print("\nInvalid entry.");
                        System.out.print("\nAre you (s)ingle, (m)arried, or (c)ohabiting?");
                        System.out.print("\nEnter s, m, or c ==> ");
                        maritalStatus = sc.next().charAt(0);
                    } while (maritalStatus != 's' && maritalStatus != 'S' && maritalStatus != 'm' && maritalStatus != 'M' && maritalStatus != 'c' && maritalStatus != 'C');
            } 

            taxesOwed = taxableIncome * (taxRate / 100);

            //taxable income and taxes owed cannot be negative
            if (taxableIncome < 0)
            {
                taxableIncome = 0;
            }
            if (taxesOwed < 0)
            {
                taxesOwed = 0;
            }

            //tax summary
            System.out.print("\nINCOME TAX SUMMARY");
            System.out.print("\ntax rate: " + taxRate + "%");
            System.out.print("\ntaxable income: $" + taxableIncome);
            System.out.print("\ntaxes owed: $" + taxesOwed);

            //would you like to process another customer?
            System.out.print("\n\nProcess another customer? (y/n): ");
            anotherCustomer = sc.next();
            System.out.print("\n");
        } while (anotherCustomer.equalsIgnoreCase("y")); //as long as user enters 'y' or 'Y', the program will continue to calculate the income tax summary
    }
}

Answer 1

而不是在

之后重试

default: //if input for marital status is invalid
   do{ //continues to ask for valid input until user inputs a valid marital status
   } while(...);

只需跳到外循环的末尾：

default:
    System.out.print("\nInvalid entry.");
    continue;

Answer 2

你需要在你的例子中默认获得的do-while-loop中有switch-Statement，比如

boolean martialStatusValid = true
maritalStatus = sc.next().charAt(0);    
do {
    martialStatusValid = true;
    switch (maritalStatus) {
       //your cases here
       default:
           martialStatusValid = false;
           //display some kind of error message ... 
    }
} while (! martialStatusValid)

这样，只要martialStatus无效，系统就会提示用户输入新内容，然后重复切换。

有一点值得注意的是Launes＆＃34; continue-solution：这将启动外部do循环的下一次迭代，所以基本上重启你的程序。如果您有更多具有用户输入的章节，那么可能不是您所追求的。如果你想要求性生活等。

输入验证Java

2 个答案: