嵌套 if 语句 - 无法执行嵌套语句

Question

我正在尝试使下面的嵌套语句正常工作，但在让它们在第一条语句之后执行时遇到问题。我尝试嵌套语句，但只是第一个 if 执行。非常感谢任何有关格式化的反馈，我知道可能有更有效的方法来实现这一点，但我必须使用嵌套语句执行代码。

package incometax;

import java.util.Scanner;
import java.text.DecimalFormat;

public class IncomeTax {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
DecimalFormat df = new DecimalFormat ("#,###,000.00");

String singleStatus = "single";
String marriedStatus = "married";
String maritalStatus = "";
double annualIncome = 0;
double taxAmount = 0;

System.out.println("Please enter your martial status: ");
maritalStatus = scnr.next();
 if (maritalStatus.compareTo(singleStatus) == 0){
     System.out.println("Please enter your annual income: ");
     annualIncome = scnr.nextDouble();

         if (annualIncome <= 30000){
         taxAmount = (annualIncome * .15);
         System.out.println("Based on annual income of "+ "$ " +        
         df.format(annualIncome) + " your tax is " + "$ " +   
         df.format(taxAmount));

             if (annualIncome > 30000){
             taxAmount = (annualIncome * .25);
             System.out.println("Based on annual income of "+ "$ " +   
             df.format(annualIncome) + 
             " your tax is " + "$ " + df.format(taxAmount));
             }
         }
         else {
              if (maritalStatus.compareTo(marriedStatus) == 0){

                 if(annualIncome <= 30000){
                 taxAmount = (annualIncome * .12);
                 System.out.println("Based on annual income of "+ "$ "  
                 +  df.format(annualIncome) + 
                 " your tax is " + "$ " + df.format(taxAmount));

                     if(annualIncome > 30000){
                     taxAmount = (annualIncome * .20);
                     System.out.println("Based on annual income of "+  
                     "$ " +  df.format(annualIncome) + 
                     " your tax is " + "$ " + df.format(taxAmount));
                     }
                  }
               }
             }
        }  
}
}

Answer 1

当annualIncome <= 30000 时，您将进入第一个if。但是嵌套 if 中的条件是annualIncome > 30000。这将永远是错误的。尝试if else 而不是嵌套的if

if (annualIncome <= 30000) {
    taxAmount = (annualIncome * .15);
    System.out.println("Based on annual income of "+ "$ " +        
        df.format(annualIncome) + " your tax is " + "$ " +   
        df.format(taxAmount));
}
else {
    taxAmount = (annualIncome * .25);
    System.out.println("Based on annual income of "+ "$ " +   
        df.format(annualIncome) + 
        " your tax is " + "$ " + df.format(taxAmount));
}

Answer 2

您似乎放错了 if 语句的括号。 试试这段代码，它应该可以工作

package incometax;

import java.util.Scanner;
import java.text.DecimalFormat;

public class IncomeTax {
    public static void main(String[] args) {
        Scanner scnr = new Scanner(System.in);
        DecimalFormat df = new DecimalFormat ("#,###,000.00");

        String singleStatus = "single";
        String marriedStatus = "married";
        String maritalStatus = "";
        double annualIncome = 0;
        double taxAmount = 0;

        System.out.println("Please enter your martial status: ");
        maritalStatus = scnr.next();
        if (maritalStatus.compareTo(singleStatus) == 0){
            System.out.println("Please enter your annual income: ");
            annualIncome = scnr.nextDouble();

            if (annualIncome <= 30000){
                taxAmount = (annualIncome * .15);
                System.out.println("Based on annual income of "+ "$ " +        
                df.format(annualIncome) + " your tax is " + "$ " +   
                df.format(taxAmount));
            } else {
                taxAmount = (annualIncome * .25);
                System.out.println("Based on annual income of "+ "$ " +   
                df.format(annualIncome) + 
                " your tax is " + "$ " + df.format(taxAmount));
            }
        } else if (maritalStatus.compareTo(marriedStatus) == 0){

            if(annualIncome <= 30000){
                taxAmount = (annualIncome * .12);
                System.out.println("Based on annual income of "+ "$ "  
                +  df.format(annualIncome) + 
                " your tax is " + "$ " + df.format(taxAmount));
            } else {
                taxAmount = (annualIncome * .20);
                System.out.println("Based on annual income of "+  
                "$ " +  df.format(annualIncome) + 
                " your tax is " + "$ " + df.format(taxAmount));
            }
        }
    }
}  

Answer 3

一个不错的 IDE 将能够格式化您的代码以使这种嵌套问题更加明显。

这可能不是问题的一部分，但您也有几行重复的代码，请查看方法。例如以下更干净（注意没有验证婚姻状况或年收入）

import java.text.DecimalFormat;
import java.util.Scanner;

public class IncomeTax
{

    private static final DecimalFormat DF = new DecimalFormat("#,###,000.00");

    private static final String SINGLE_STATUS = "single";
    private static final String MARRIED_STATUS = "married";

    private static final double SINGLE_LOW_RATE = .15;
    private static final double SINGLE_HIGH_RATE = .25;

    private static final double MARRIED_LOW_RATE = .12;
    private static final double MARRIED_HIGH_RATE = .20;

    private static final int LOWER_BRACKET = 30000;

    public static void main(String[] args)
    {

        Scanner scnr = new Scanner(System.in);

        String maritalStatus;
        double annualIncome;

        System.out.println(
            "Please enter your martial status: ");
        maritalStatus = scnr.next();

        System.out.println("Please enter your annual income: ");
        annualIncome = scnr.nextDouble();

        if (SINGLE_STATUS.equalsIgnoreCase(maritalStatus))
        {
            printTaxRate(annualIncome, SINGLE_LOW_RATE, SINGLE_HIGH_RATE);
        } else
        {
            if (MARRIED_STATUS.equalsIgnoreCase(maritalStatus))
            {
                printTaxRate(annualIncome, MARRIED_LOW_RATE, MARRIED_HIGH_RATE);
            }
        }
    }

    private static double calcTaxAmount(double annualIncome, double taxRate)
    {
        return annualIncome * taxRate;
    }

    private static void printTaxRate(double annualIncome, double lowRate, double highRate)
    {
        double taxAmount;
        if (annualIncome <= LOWER_BRACKET)
        {
            taxAmount = calcTaxAmount(annualIncome, lowRate);
        } else
        {
            taxAmount = calcTaxAmount(annualIncome, highRate);
        }

        System.out.println("Based on annual income of " + "$ "
            + DF.format(annualIncome)
            + " your tax is " + "$ " + DF.format(taxAmount));
    }
}