Java Scanner Delimiter Usage

Question

I\'d like to specify a delimiter for a scanner that splits on some pattern, but doesn\'t remove that pattern from the tokens. I can\'t seem to make this work, as anything t

Answer 1

You can use a positive look ahead in your regex. Look aheads (and behinds) are not included in the match, so they won't be "eaten" by the Scanner. This regex will probably do what you want:

(?=text/numbers)

The delimiter will be the empty String right before the sub-string text/numbers.

Here's a small demo:

public class Main {
    public static void main(String[] args) {
        String text = "text/numbers mix\n"+
                "numbers\n"+
                "numbers\n"+
                "text/numbers mix\n"+
                "numbers\n"+
                "numbers\n"+
                "numbers";
        String regex = "(?=text/numbers)";
        Scanner scan = new Scanner(text).useDelimiter(regex);
        while(scan.hasNext()) {
            System.out.println("------------------------");
            System.out.println(">"+scan.next().trim()+"<");
        }
    }
}

which produces:

------------------------
>text/numbers mix
numbers
numbers<
------------------------
>text/numbers mix
numbers
numbers
numbers<