读取数据、操作数据和输出数据时出错

Question

我的 while 循环出现问题。我收到了

Exception in thread "main" java.util.NoSuchElementException: No line found.
at java.util.Scanner.nextLine(Scanner.java:1516)
at Payroll.main(Payroll.java:70)`

这是代码：

import javax.swing.JOptionPane;
import java.text.DecimalFormat;
import java.io.*;
import java.util.Scanner;

public class Payroll
{
public static void main(String[] args) throws IOException //throws exceptions
{
    //Declare variables
    String fileInput;               // To hold file input
    String fileOutput;              // To hold file output
    String date;                        // To hold the date
    String userInput;                   // To hold user input from JOptionPane
    String employeeID = "";         // To hold employee ID
    String employeeName = "";       // To hold employee name
    double hours = 0.0;             // To hold employee hours
    double wageRate = 0.0;          // To hold employee wage rate
    double taxRate = 0.0;           // To hold employee tax rate
    double taxWithheld;             // To hold employee taxes withheld
    double grossPay;                    // To hold employee gross pay
    double netPay;                      // To hold employee net pay
    double totalGross = 0.0;        // To hold total gross pay
    double totalTax = 0.0;          // To hold total tax withheld
    double totalNet = 0.0;          // To hold total net pay
    
    DecimalFormat money = new DecimalFormat("#,##0.00");// used to format money later on        
    
    date = JOptionPane.showInputDialog("Enter pay period ending date (mm/dd/yyyy): "); //hold user input into date
    
    //Open the input file
    File file = new File("EmployeeList.txt");
    
    if (!file.exists())// check to see if the file exists
        {
            JOptionPane.showMessageDialog(null, "The file EmployeeList.txt is not found.");
            System.exit(0);
        }  
        
    // Create Scanner object to enable reading data from input file
   Scanner inputFile = new Scanner(file);
    
    // Create FileWriter and PrintWriter objects to enable
  // writing (appending not overwriting) data to text file
  FileWriter fwriter = new FileWriter("PastPayrolls.txt", true);
  PrintWriter outputFile = new PrintWriter(fwriter);

    outputFile.println("PAY PERIOD ENDING DATE: " + date);
    
    
            
    while (inputFile.hasNext())
    {           
        employeeID = inputFile.nextLine();                                      // Read info from first line and store it in employeeID
        employeeName = inputFile.nextLine();                                    // Read info from next line and store it in employeeName
        
        userInput = JOptionPane.showInputDialog("Employee Name: " + 
                                                             employeeName +
                                                            "\nEnter number of" +   // display employee name and ask for number of hours worked
                                                             " hours worked:");
                                                                             
        hours = Double.parseDouble(userInput);                                  // Store user's parsed input into hours
        wageRate = inputFile.nextDouble();                                      // Read info from next line and store it in wageRate
        taxRate = inputFile.nextDouble();                                       // Read info from next line and store it in taxRate
        inputFile.nextLine();                                                       // Read blank line
        
        Paycheck paycheck = new Paycheck(employeeID, employeeName, wageRate, taxRate, hours);
        
        paycheck.calcWages();
        
        outputFile.println("Employee ID: " + paycheck.getEmployeeID());
        outputFile.println("Name: " + paycheck.getEmployeeName());
        outputFile.println("Hours Worked: " + hours);
        outputFile.println("Wage Rate: $" + money.format(paycheck.getWageRate()));
        outputFile.println("Gross Pay: $" + money.format(paycheck.getGrossPay()));
        outputFile.println("Tax Rate: " + paycheck.getTaxRate());
        outputFile.println("Tax Withheld: $" + money.format(paycheck.getTaxWithheld()));
        outputFile.println("Net Pay: $" + money.format(paycheck.getNetPay()));
        
        
        JOptionPane.showMessageDialog(null, "Employee ID: " + paycheck.getEmployeeID() +
                                               "\nName: " + paycheck.getEmployeeName() +
                                                "\nHours Worked: " + hours +
                                                "\nWage Rate: $" + money.format(paycheck.getWageRate()) +
                                                "\nGross Pay: $" + money.format(paycheck.getGrossPay()) +
                                                "\nTax Rate: " + paycheck.getTaxRate() +
                                                "\nTax Withheld: $" + money.format(paycheck.getTaxWithheld()) +
                                                "\nNet Pay: $" + money.format(paycheck.getNetPay()));
        
        totalGross += paycheck.getGrossPay();
        totalTax += paycheck.getTaxWithheld();
        totalNet += paycheck.getNetPay();
        
        inputFile.nextLine();
        }

    }// end while loop
    
    JOptionPane.showMessageDialog(null, "Total Pay Period Gross Payroll: $" + money.format(totalGross) +
                                           "Total Pay Period Period Tax Withheld: $" +  money.format(totalTax)+
                                            "Total Pay Period Net Payroll: $" + money.format(totalNet));
    
    outputFile.println();
    outputFile.println("TOTAL PAY PERIOD GROSS PAYROLL: $" + money.format(totalGross));
    outputFile.println("TOTAL PAY PERIOD TAX WITHHELD: $" + money.format(totalTax));
    outputFile.println("TOTAL PAY PERIOD NET PAYROLL: $" + money.format(totalNet));
    
    inputFile.close();
    outputFile.close();
 }
}'

这是包含我的薪水类的其他代码：

`public class Paycheck
{
//Declare variables
private final String EMPLOYEE_ID;       // Employee ID
private final String EMPLOYEE_NAME;     // Employee Name
private final double WAGE_RATE;         // Wage Rate
private final double TAX_RATE;          // Tax Rate
private final double HOURS_WORKED;      // Hours Worked
private double grossPay;                    // Gross Pay
private double taxWithheld;             // Tax Withheld
private double netPay;                      // Net Pay

// Constructor
Paycheck(String id, String name, double wage, double tax, double hours)
{
    EMPLOYEE_ID = id;
    EMPLOYEE_NAME = name;
    WAGE_RATE = wage;
    TAX_RATE = tax;
    HOURS_WORKED = hours;
}

public void calcWages()//calculates wages
{
    grossPay = HOURS_WORKED * WAGE_RATE;
    taxWithheld = grossPay * TAX_RATE;
    netPay = grossPay - taxWithheld;

}//end calcWages

public String getEmployeeID()//returns Employee's ID
{
    return EMPLOYEE_ID;
}//end getEmployeeID

public String getEmployeeName()//returns Employee's name
{
    return EMPLOYEE_NAME;
}//end getEmployeeName

public double getWageRate()//returns Employee's wage rate
{
    return WAGE_RATE;
}//end getWageRate

public double getTaxRate()//returns Employee's tax rate
{
    return TAX_RATE;
}//end getTaxRate

public double getHoursWorked()//returns Employee's hours worked
{
    return HOURS_WORKED;
}//end getHoursWorked

public double getGrossPay()//returns Employee's gross pay
{
    return grossPay;
}//end getGrossPay

public double getTaxWithheld()//returns Employee's tax withheld
{
    return taxWithheld;
}//end getTaxWithheld

public double getNetPay()//returns Employee's net pay
{
    return netPay;
}//end getNetPay
}`

抱歉代码太长。我认为有人可能需要大部分代码才能找出问题所在。如果有更好的方法来使用更好的方法，我将被迫坚持简单性，所以请尝试在这段代码的范围内工作。顺便说一句，我是 Java 初学者。

谢谢！

Answer 1

我猜这是因为您有：

 while (inputFile.hasNext())

使用Scanner.hasNextLine。

编辑：

我用您的示例输入测试了您的代码。我现在明白你的意思了。

while ( inputFile.hasNextLine() ) {
            employeeID = inputFile.nextLine(); // Read info from first line and store it in employeeID
            employeeName = inputFile.nextLine(); // Read info from next line and store it in employeeName

            userInput = JOptionPane.showInputDialog( "Employee Name: " + employeeName + "\nEnter number of" + // display employee name and ask for number of hours worked
            " hours worked:" );

            hours = Double.parseDouble( userInput ); // Store user's parsed input into hours
            wageRate = inputFile.nextDouble(); // Read info from next line and store it in wageRate
            taxRate = inputFile.nextDouble(); // Read info from next line and store it in taxRate

使用 hasNextLine 作为条件只会确保下一次调用 nextLine 有效。但是，您调用 nextLine 两次，然后调用 nextDouble 。您可以 (1) 确保您进行的调用与文件完全匹配，或者 (2) 每次调用 next 时检查是否有下一个标记。我认为（1）是你的问题。

我能够使用以下内容修复您的程序：

while ( inputFile.hasNextLine() ) {
    employeeID = inputFile.nextLine();
    employeeName = inputFile.nextLine();
    userInput = JOptionPane.showInputDialog( "Employee Name: " + employeeName + "\nEnter number of hours worked:" );
    hours = Double.parseDouble( userInput );
    wageRate = Double.parseDouble(inputFile.nextLine());
    taxRate = Double.parseDouble(inputFile.nextLine());
    Paycheck paycheck = new Paycheck( employeeID, employeeName, wageRate, taxRate, hours );
    paycheck.calcWages();
    JOptionPane.showMessageDialog( null, "Employee ID: " + 
            paycheck.getEmployeeID() + "\nName: " + 
            paycheck.getEmployeeName() + "\nHours Worked: " + 
            hours + "\nWage Rate: $" + 
            money.format( paycheck.getWageRate() ) + "\nGross Pay: $" + 
            money.format( paycheck.getGrossPay() ) + "\nTax Rate: " + 
            paycheck.getTaxRate() + "\nTax Withheld: $" + 
            money.format( paycheck.getTaxWithheld() ) + "\nNet Pay: $" + 
            money.format( paycheck.getNetPay() ) );
}

文件内容：

00135
John Doe
10.50
0.20
00179
Mary Brown
12.50
1.20