java中的文件输入流 - 计算数据

Question

我正在尝试将文件读入程序，然后获取 fileIn 对象并对它们进行计算以创建一个新变量，特别是读取价格并计算销售税。我以前做过这种类型的程序，我是按照下面的代码来做的。出于某种原因，这次我在运行程序时在控制台中收到此错误消息。

   Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:909)
at java.util.Scanner.next(Scanner.java:1530)
at java.util.Scanner.nextDouble(Scanner.java:2456)
at TaxCalculator.main(TaxCalculator.java:42)

到目前为止，我发现 .next() 方法给了我错误，因为我可以用 .nextLine(); 完整地阅读，但这违背了程序的目的。

    import java.io.FileInputStream;
    import java.util.Scanner;
    import java.io.FileNotFoundException;

    public class TaxCalculator {

/**
 * @param args
 */
public static void main(String[] args) {
    // TODO Auto-generated method stub

    Scanner fileIn = null; //Initializes fileIn to empty

    //Declares variables
    String text;
    int value;
    double price;
    double tax;

    try 
    {
        //Attempt to open the file
        fileIn = new Scanner (
                new FileInputStream ("Basket.txt"));

        }
    catch (FileNotFoundException e)
    {
        //This block executed if the file is not found
        //then the program exits
        System.out.println("File not found.");
        System.exit(0);
    }



    //Read and print in lines
    value = fileIn.nextInt();
    text = fileIn.next();
    price = fileIn.nextDouble();
    tax = (price * .10);

    System.out.printf("%1d %2s %3.2f", value, text, price   );


    /**
    //Read and print next input line
    value = fileIn.nextInt();
    text = fileIn.next();
    price = fileIn.nextDouble();
    tax = (price * .10);    
    System.out.printf("%-7s %20s %22s %30.2f %n", value , text, text,
            price);
    //Read and print next input line
    value = fileIn.nextInt();
    text = fileIn.next();
    price = fileIn.nextDouble();
    tax = (price * .10);    
    System.out.printf("%-7s %18s %22s %30.2f %n", value , text, text,
            price);
    **/
    // Close file
    fileIn.close();

    System.out.println("\nEnd of Tax Calculator");


  }

 }

任何帮助将不胜感激，谢谢。 -编辑 - Basket.txt的内容

1 item at 10.49
1 special item at 13.99
1 candy bar at 0.75

Input 2:
1 imported pack of cigarettes at 10.00
1 imported bottle of alcohol at 44.50

Input 3:

1 imported bottle of alcohol at at 25.99
1 bottle of alcohol at 15.99
1 packet of cough drops at 4.99
1 box of imported cigarettes at 9.25

Answer 1

由 Scanner 抛出以指示检索到的令牌与预期类型的​​模式不匹配，或者令牌超出预期类型的​​范围。

这意味着你的程序试图读取一个不是整数的整数值。

Answer 2

Basket.txt 包含带整数的字符串，

value = fileIn.nextInt(); text = fileIn.next(); price = fileIn.nextDouble();

读取前三行，所以前三行应该是 Integer String double 如果是字符串或混合字符串，它会显示

MismatchException