有关使用Scanner时InputMismatchException的问题 [英] Question about InputMismatchException while using Scanner

问题描述

问题:

输入文件:客户的帐号，帐户余额为月初，交易类型(提款，入金，利息)，交易金额

Input file: customer’s account number, account balance at beginning of month, transaction type (withdrawal, deposit, interest), transaction amount

输出:帐号，期初余额，期末余额，已付利息总额，存款总额，存款，总提款额，提款次数

Output: account number, beginning balance, ending balance, total interest paid, total amount deposited, number of deposits, total amount withdrawn, number of withdrawals

package sentinel;

import java.io.*;
import java.util.*;

public class Ex7 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws FileNotFoundException
 {
        int AccountNum;
        double BeginningBalance;
        double TransactionAmount;
        int TransactionType;
        double AmountDeposited=0;
        int NumberOfDeposits=0;
        double InterestPaid=0.0;
        double AmountWithdrawn=0.0;
        int NumberOfWithdrawals=0;
        boolean found= false;

        Scanner inFile = new Scanner(new FileReader("Account.in"));
        PrintWriter outFile = new PrintWriter("Account.out");

           AccountNum = inFile.nextInt();
           BeginningBalance= inFile.nextDouble();

           while (inFile.hasNext())
        {
               TransactionAmount=inFile.nextDouble();
               TransactionType=inFile.nextInt();
                outFile.printf("Account Number: %d%n", AccountNum);
                outFile.printf("Beginning Balance: $%.2f %n",BeginningBalance);
                outFile.printf("Ending Balance: $%.2f %n",BeginningBalance);
                outFile.println();
               switch (TransactionType)
            {
                   case '1': // case 1 if we have a Deposite
                BeginningBalance = BeginningBalance
                        + TransactionAmount;
                AmountDeposited = AmountDeposited
                        + TransactionAmount;
                NumberOfDeposits++;
                outFile.printf("Amount Deposited: $%.2f %n",AmountDeposited);
                outFile.printf("Number of Deposits: %d%n",NumberOfDeposits);
                outFile.println();

                break;
                   case '2':// case 2 if we have an Interest
                BeginningBalance = BeginningBalance
                        + TransactionAmount;
                InterestPaid = InterestPaid
                        + TransactionAmount;
                outFile.printf("Interest Paid: $%.2f %n",InterestPaid);
                outFile.println();

                break;

                   case '3':// case 3 if we have a Withdraw
                BeginningBalance = BeginningBalance
                        - TransactionAmount;
                AmountWithdrawn = AmountWithdrawn
                        + TransactionAmount;
                NumberOfWithdrawals++;
                outFile.printf("Amount Withdrawn: $%.2f %n",AmountWithdrawn);
                outFile.printf("Number of Withdrawals: %d%n",NumberOfWithdrawals);
                outFile.println();

                    break;

                default:
                System.out.println("Invalid transaction Tybe: " + TransactionType
                        + TransactionAmount);

               }
           }
           inFile.close();
           outFile.close();
    }
}

但这是给我的:

Exception in thread "main" java.util.InputMismatchException
        at java.util.Scanner.throwFor(Scanner.java:840)
        at java.util.Scanner.next(Scanner.java:1461)
        at java.util.Scanner.nextInt(Scanner.java:2091)
        at java.util.Scanner.nextInt(Scanner.java:2050)
        at sentinel.Ex7.main(Ex7.java:36)
Java Result: 1

推荐答案

我将按照以下步骤进行操作:

This is how I would proceed:

• 在 API中查找该异常的含义文档.
• 考虑它如何发生，发生在哪一行(请查看您的堆栈跟踪).如果您不知道如何读取堆栈跟踪，请这是一个教程.
• 如果您无法立即看到原因，请设置一个断点，并通过调试器运行该断点，以在异常发生之前可视化"程序的当前状态.

您可能还不知道如何使用调试器，尽管有些人可能不同意，但我认为现在还为时过早.在此处上有一些关于如何使用调试器的优秀视频教程.祝你好运！

You might not know how to use your debugger yet, and while some might not agree, I think it's never too early. There are some excellent video tutorials on how to use the debugger here. Good luck!

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