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+//https://www.hackerrank.com/challenges/positive-lookahead%0Apublic class Solution %7B%0A  public static void main(String%5B%5D args) %7B%0A    Regex_Test tester = new Regex_Test();%0A    tester.checker(%22o(?=oo)%22);%0A  %7D%0A%7D%0A

Create positive-lookahead.java