// https://www.hackerrank.com/challenges/java-regex/problem import java.util.Scanner; public class JavaRegex { public static void main(String[] args){ Scanner scanner = new Scanner(System.in); while(scanner.hasNext()){ String IP = scanner.next(); System.out.println(IP.matches(new MyRegex().pattern)); } scanner.close(); } } class MyRegex { final String pattern = "([0-1]?\\d{1,2}[.]|2([0-4]\\d|5[0-5])[.]){3}([0-1]?\\d{1,2}|2([0-4]\\d|5[0-5]))"; }