Question

    import java.io.*;               //Importing to read from file.
import java.util.Scanner;       //Importing Scanner class.
import java.text.DecimalFormat; //Importing DecimalFormat class.


public class StockAssessment
{
    public static void main(String[] args)  throws IOException
    {
        System.out.println("Joe Williams");

        // Setting up DecimalFormat.
        DecimalFormat money = new DecimalFormat("$###.##");

        // Setting up the scanner.
        Scanner keyboard = new Scanner(System.in);

        /*
            Prompting for the file name and initalizing
            it to fileName.
        */
        System.out.print("Name of the file? ");
        String fileName = keyboard.nextLine();

        //Opening the file.
        File theFile = new File(fileName);
        Scanner inputFile = new Scanner(theFile);

        //Making sure the file exists.
        if (!theFile.exists())
        {
            System.out.println("========================");
            System.out.println("No transactions processed.");
            System.exit(0);
        }

        //Getting data from stock file.
        while (inputFile.hasNext())
        {
            String str = inputFile.nextLine();
            int shareAmount = inputFile.nextInt();
            double purchasePrice = inputFile.nextDouble();
            double purchCommissRate = inputFile.nextDouble();
            double salePrice = inputFile.nextDouble();
            double saleComiss = inputFile.nextDouble();
        }
        inputFile.close();

        }

    }

我不明白为什么这个代码会找到一个文件而不是另一个文件，如果它们都在源代码所在的文件夹中。代码不完全在那里，我有一个等待放入代码但需要我能够打开Java当前无法找到的文件的方法。如果有人能让我知道如何解决这个问题，那将非常感激。

Name of the file? StockData.txt
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.nextInt(Scanner.java:2160)
        at java.util.Scanner.nextInt(Scanner.java:2119)
        at StockAssessment.main(StockAssessment.java:46)
Press any key to continue . . .

一个名为EmptyFile.txt，另一个名为StockData.txt。它识别空文件但不识别库存数据

DELL: Dell Inc
125 25.567  0.025   28.735  0.025
MSFT: Microsoft
34.1    -15.75  0.012   15.90   0.013
GOOG: Google
56.5    58.125  0.032   67.975  0.030
IBM: IBM Corp
87.3    8.875   0.015   7.500   0.020

Answer 1

如果找不到该文件，那么它应该给你

java.io.FileNotFoundException: StockData (The system cannot find the file specified).

在你的情况下，问题出在某处。

        String str = inputFile.nextLine();
        int shareAmount = inputFile.nextInt();
        double purchasePrice = inputFile.nextDouble();
        double purchCommissRate = inputFile.nextDouble();
        double salePrice = inputFile.nextDouble();
        double saleComiss = inputFile.nextDouble();

如果请求的值与此结构不匹配，则抛出InputMismatchException。

<强>更新

要使代码生效，您需要更改在StockData中编写数据的方式。

DELL: Dell Inc 
125 
25.567 
0.025 
28.735 
0.025

Answer 2

在 StockData.txt 中，shareAmount不是所有公司的int。例如，

MSFT: Microsoft
34.1 ...
GOOG: Google
56.5 ...

因此，要么将金额列为整数，要么使用nextDouble()来阅读它们。

String str = inputFile.nextLine();

// cast to int; 34.1 becomes 34
int shareAmount = (int) inputFile.nextDouble();

Answer 3

您必须添加另一个nextLine才能完成阅读带数字的行。

while (inputFile.hasNext())  {
        String str = inputFile.nextLine();
        int shareAmount = inputFile.nextInt();
        double purchasePrice= inputFile.nextDouble();
        double purchCommissRate = inputFile.nextDouble();
        double salePrice = inputFile.nextDouble();
        double saleComiss = inputFile.nextDouble();

        inputFile.nextLine();
    }

或者，将所有行都读为String

 while( inputFile.hasNextLine() ){
     String name = inputFile.nextLine();
     String data = inputFile.nextLine();
     Scanner ds = new Scanner( data );
     int shareAmount = ds.nextInt();
     double purchasePrice= ds.nextDouble();
     double purchCommissRate = ds.nextDouble();
     double salePrice = ds.nextDouble();
     double saleComiss = ds.nextDouble();
}

Java在同一位置找到一个文件而不是另一个文件

3 个答案: