当我输入一个double时，nextDouble()会引发InputMismatchException [英] nextDouble() throws an InputMismatchException when I enter a double

问题描述

import java.util.*;

class Averager
{
    public static double unlimited()
    {
        int count = 0;
        double sum = 0;
        Scanner scan = new Scanner(System.in);
        while(scan.hasNext())
        {
            double d = scan.nextDouble();
            sum += d;
            count++;
        }
        double ave = sum/count;
        return ave;
    }

    public static void main(String[] args) {
        System.out.println(unlimited()+"\n");
    }
}

使用整数时没有错误，但是如果我使用带点的数字，则会出现错误.

There is no error when I use integers but if I use numbers with point in it a error appears.

$ javac Averager.java; java Averager
0.5
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.nextDouble(Scanner.java:2387)
    at Averager.unlimited(Averager.java:12)
    at Averager.main(Averager.java:21)

据我所知，0.5应该加倍.如果没有，请有人纠正我.

To my best understanding 0.5 should be covered by double. If not please can someone correct me.

推荐答案

它可能取决于语言环境.小数例如在瑞典写为0.5.

It might be locale dependent. Decimal numbers are e.g written as 0,5 in Sweden.

更改代码，使其显示例如:

Change your code so that it says e.g.:

Scanner scan = new Scanner(System.in);
scan.useLocale(Locale.US);

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