What does each element do ("(.)\\1{1,}", "$1") in this code?

Question

import java.util.Scanner;

public class redigetajs {
    public static void main(String args[]){

        Scanner scan= new Scanner(System.in);
        System.out.println("Input text!");
        String teksts= scan.nextLine();
        System.out.println("text after change!");
        System.out.println(teksts.replaceAll("(.)\\1{1,}", "$1"));
    }
}

`{1,}` is the same as `+`. [Check the SO regex reference](http://stackoverflow.com/q/22937618) — HamZa, May 06 '14 at 11:35

score 3 · Answer 1 · answered May 06 '14 at 11:34

3

It matches sequences of identical characters and collapses them into only one occurrence.

Example: "aaaaabcccdd" -> "abcd"

answered May 06 '14 at 11:34

cadrian

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score 1 · Answer 2 · answered May 06 '14 at 11:42

1

Suexpression duplicate a group character and removed:

(.) - group, also referenced as $1
\\1 - subexpression followed it
{1,} - to repeat one or more times

answered May 06 '14 at 11:42

Roman C

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What is $1? What happens when replace with $1? – mahesh May 06 '14 at 11:45
1

substitute group match and replace with it – Roman C May 06 '14 at 11:46

score 1 · Answer 3 · answered May 06 '14 at 12:08

1

Perfect tool for this:

http://regex101.com/r/kF3uB7

need 30 characters :)

answered May 06 '14 at 12:08

Jan

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What does each element do ("(.)\\1{1,}", "$1") in this code?

3 Answers3