here is my code without regex in java

import java.io.; import java.util.;

public class Solution {

public static void main(String[] args) throws IOException{
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

String input = reader.readLine(); while (input != null){ System.out.println(MyRegex.checkIP (input)); input = reader.readLine(); } }

}

class MyRegex { public static boolean checkIP (String input) { int startNum = 0 ; for (int i=1 ; i < 5 ; i++){ int currentDot = input.indexOf(".", startNum);

  if (currentDot == -1 && i != 4){return false ;}
 int currentNum ;
 try {
    if (currentDot == -1) {currentDot = input.length();}
     currentNum = (int) Integer.parseInt(input.substring(startNum, currentDot));

if (currentNum > 255) {return false;}
 if (input.substring(startNum, currentDot).length() > 3 || input.substring(startNum, currentDot).length() == 0) {return false;} 
 if (input.contains(" ")){return false;}
}     
 catch (Exception e){
    return false ;
 }
 startNum = currentDot + 1;
 if (i == 3 && input.indexOf(".", startNum) > 0){return false ;}

} return true; }
}

import java.util.Scanner;

public class Solution { public static void main(String[] args) { Scanner scan = new Scanner(System.in); while (scan.hasNext()) { System.out.println(new MyRegex(scan.nextLine()).isValidIp()); } scan.close(); } }

final class MyRegex { private final String val; private static final String IP_REG_PATTERN_STRING = "((25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])\.){3}" + "(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]?[0-9])";

public MyRegex(String val) {
    this.val = val;
}

public boolean isValidIp() {
    return this.val.matches(IP_REG_PATTERN_STRING);
}

}

String regex = "^(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{1,2})\.(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{1,2})\.(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{1,2})\.(25[0-5]|2[0-4][0-9]|[0-1]?[0-9]{1,2})$";

Here is Java Regex solution - https://programmingoneonone.com/hackerrank-java-regex-problem-solution.html

String pattern = "^((25[0-5]|2[0-4]\d|[0-1]?[0-9]{0,2})\.){3}"+ "(25[0-5]|2[0-4]\d|[0-1]?[0-9]{0,2})$";