java - Validate if input string is a number between 0-255 using regex

Question

I am facing problem while matching input string with Regex. I want to validate input number is between 0-255 and length should be up to 3 characters long. code is working fine but when I input 000000 up to any length is shows true instead false.

Here is my code :-

String IP = "000000000000000";
        System.out.println(IP.matches("(0*(?:[0-9][0-9]?|[0-2][0-5][0-5]))"));

Answer 1

Tested this:

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

It works for the following:

• IP Addresses xxx.xxx.xxx.xxx / xx.xx.xx.xx / x.x.x.x / mix of these.
• Leading zeros are allowed.
• Range 0-255 / maximum 3 digts.