文件中的扫描仪InputMismatchException [英] Scanner InputMismatchException from file

问题描述

使用Java做我的第一步，这是我的问题:

Doing my first steps with Java, here's my problem:

1.)可以读取rawData.txt:

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
import static java.lang.System.out;

class ReadAndWrite {

    public static void main(String args[]) 
                         throws FileNotFoundException {

        Scanner diskScanner = new Scanner(new File("rawData.txt")); 
        String diskString;
        diskString = diskScanner.nextLine();
        out.println(diskString);
        diskScanner.close();
    }
}

eclipse控制台中的结果是:

The result in eclipse console is :

>19.5 5 

所以我想内容可以阅读.

So I guess the content can be read.

但是:nextDouble()和nextInt()不起作用:

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

class ReadAndWrite {

    public static void main(String args[]) 
                         throws FileNotFoundException {

        Scanner diskScanner = new Scanner(new File("rawData.txt"));
        double unitPrice, quantity;
        unitPrice = diskScanner.nextDouble();
        quantity = diskScanner.nextInt();

        [...]

        diskScanner.close();

    }
}

控制台发出的错误消息是:

The error message from console is:

Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:864)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextDouble(Scanner.java:2413)
    at ReadAndWrite.main(ReadAndWrite.java:16)

那我该怎么做才能理解这个问题?

So what can I do to understand the problem?

推荐答案

我刚刚在计算机上进行了测试，发现了问题所在.预期的double格式取决于Locale.在某些国家/地区，小数位数用,分隔，而有些则用..

I have just made a test on my machine and I've found the problem. Expected double format depends on Locale. In some countries the decimal digits are separated with , and some with ..

    Scanner diskScanner = new Scanner(new File("rawData.txt")).useLocale(Locale.ENGLISH);

将解决问题.否则，请从以下位置更改文件

will solve the problem. Otherwise change your file from

19.5 5

到

19,5 5

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