java - How do I use a dot as a delimiter?

Question

import java.util.Scanner;
public class Test{
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);
        input.useDelimiter(".");
        String given = input.next();
        System.out.println(given);
    }
}

When I run the above code and type in asdf. then enter, I get nothing.

It works fine with "," ";" """ "" or whatever, but just not with "."... So is there something about a dot or is it just a problem with Eclipse IDE or whatever?

Answer 1

Scanner is using regular expression (regex) as delimiter and dot . in regex is special character which represents any character except line separators. So if delimiter is any character when you write asdf. each of its character will be treated as delimiter, not only dot. So each time you will use next() result will be empty string which exists in places I marked with |

a|s|d|f|.

To create dot literal you need to escape it. You can use . for that. There are also other ways, like using character class [.].

So try with

input.useDelimiter("\.");