当我输入double时，nextDouble（）会抛出exception

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如果我使用带有点的数字则会出现错误。

 $ 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应该用双倍覆盖。 如果不是，请有人纠正我。

Answer 1

它可能依赖于语言环境。 在瑞典，十进制数字例如写为0,5。

更改您的代码，以便说明例如：

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

Answer 2

 This worked for me, changing the locale did not. Scanner sc = new Scanner(System.in); // val = sc.nextDouble(); - crashes with java.util.NoSuchElementException // If Java crashes with legal Java code, wrap the call in a hasNextLine() test if (sc.hasNextLine()) { val = sc.nextDouble(); } 

java.util.NoSuchElementException：找不到行