In this HackerRank Java Regex problem in the java programming language, you need to write a class called MyRegex which will contain a string pattern. You need to write a regular expression and assign it to the pattern such that it can be used to validate an IP address. 

HackerRank Java Regex problem solution


HackerRank Java Regex problem solution.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Scanner;

class Solution{

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            String IP = in.next();
            System.out.println(IP.matches(new MyRegex().pattern));
        }

    }
}

//Write your code here
class MyRegex {

String ip0to255 = "(\\d{1,2}||(0|1)\\d{2}||2[0-4]\\d||25[0-5])";

public String pattern = ip0to255 + "\\." + ip0to255 + "\\." + ip0to255 + "\\." + ip0to255; 
}


Second solution

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Scanner;

class Solution{

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            String IP = in.next();
            System.out.println(IP.matches(new MyRegex().pattern));
        }

    }
}

//Write your code here
class MyRegex {
    public String pattern = "((\\d|\\d\\d|[0-1]\\d\\d|2[0-4][0-9]|25[0-5])\\.){3}(\\d|\\d\\d|[0-1]\\d\\d|2[0-4][0-9]|25[0-5])";
}

A solution in java8 programming.

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.Scanner;

class Solution{

    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            String IP = in.next();
            System.out.println(IP.matches(new MyRegex().pattern));
        }

    }
}

//Write your code here
class MyRegex {
    public String pattern = "((\\d|\\d\\d|[0-1]\\d\\d|2[0-4][0-9]|25[0-5])\\.){3}(\\d|\\d\\d|[0-1]\\d\\d|2[0-4][0-9]|25[0-5])";
}