validate_an_IP_address_RegEx.java

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

class Main{

    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));
        }

    }
}

class MyRegex {
    String p= "([0-1][0-9]{2}|2[0-4][0-9]|25[0-5]|[0-9]{1}|[0-9]{2})";
    String pattern=p+"\\."+p+"\\."+p+"\\."+p;
}