Regular Expresso- Positive Lookahead

Problem:

 https://www.hackerrank.com/contests/regular-expresso/challenges/positive-lookahead

Solution:

public class Solution {   

    public static void main(String[] args) {
       
        Regex_Test tester = new Regex_Test();
        tester.checker("o(?=oo)"); //Use '\\' instead of '\'.
   
    }
}