Parse comma-separated values with Scanner: mismatch exception

Question

I realize there are many topics on the subjects, but I couldn't fine one that responds to this case:

I have multiple lines of input, for which the format can not be edited.

For example, I have:

1

0.55,0.20,0.05

1,2,3

As you can tell, the first one is an integer, and is not delimited by anything. Next, we have 3 doubles, delimited by a comma.

I successfully got the nextInt(). When I try nextDouble(), I am getting an Input Mismatch Exception.

I already tried to use both Locale English and US.

So how would one read these inputs? First one is an int, followed by 3 doubles, and another 3 ints.

Here is the relevant code:

Scanner in = new Scanner(System.in); // tried delimiters and locale here
int tests = in.nextInt();
System.out.println(in.nextDouble()); //this is where the input exception occurs

Adrian Leonhard · Accepted Answer · 2015-02-17 01:52:56Z

2

By default, Scanner uses whitespace as delimiter. You can set a custom delimiter (commas in this case):

 Scanner s = new Scanner(input).useDelimiter("(\\s|,)+");

edited Feb 17, 2015 at 1:52

answered Feb 17, 2015 at 1:44

Adrian Leonhard

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5 Comments

Wilhelm Sorban Over a year ago

Thanks, however, if I do that delimiter, more precisely like this: "Scanner in = new Scanner(System.in).useDelimiter("\\s*|,");" my output is 0.0

Adrian Leonhard Over a year ago

@WilhelmSorban That's what I get for not testing. \s* matched between numbers, leading to 0.0 values. I fixed my answer.

Wilhelm Sorban Over a year ago

Thanks, it works now. Can you please explain why those characters, inside the string? I previously tried with useDelimiter(",") as in have a comma as delimiter, but that didnt work. The document on here was a bit confusing tutorialspoint.com/java/util/scanner_usedelimiter_string.htm

Adrian Leonhard Over a year ago

Using only a comma does not work, because some numbers are separated by spaces/newlines (=whitespace). This one means ((whitespace OR ,) one or more times). See stackoverflow.com/a/2759417/1980909 for more information.

Wilhelm Sorban Over a year ago

Indeed, because whitespaces are used as delimiter by default, I thought that if I do useDelimiter(","), it will be whitespace OR "," Now it all makes sense, thanks!

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