'Scanner double value - InputMismatchException

I tried use scanner at easiest way:

Code:

double gas, efficiency, distance, cost;
Scanner scanner = new Scanner(System.in);

System.out.print("Enter the number of gallons of gas in the tank: ");
gas = scanner.nextDouble();
System.out.print("Enter the fuel efficiency: ");
efficiency = scanner.nextDouble();

But after first input 5.1 it throws:

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 udacity.MileagePrinter.main(MileagePrinter.java:59)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

The JavaDocs state:

Thrown by a Scanner to indicate that the token retrieved does not match the
pattern for the expected type, or that the token is out of range for the expected type.

But to my mind all look correctly, and should work OK.

Questions:

  • Why this happen at this situation?
  • How to circumvent this trouble?
javainputmismatchexception


Solution 1:[1]

Make sure that you are using the correct locale

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

Maybe you are using a locale where "," is the decimal delimiter

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Viktor Mellgren

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