Java tutorial
//package com.java2s; import java.util.regex.Matcher; import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException; public class Main { public static boolean validateIPAddress(String ip) { if (ip == null || ip.isEmpty()) return false; ip = ip.trim(); if ((ip.length() < 6) & (ip.length() > 15)) return false; try { Pattern pattern = Pattern.compile( "^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$"); Matcher matcher = pattern.matcher(ip); return matcher.matches(); } catch (PatternSyntaxException ex) { return false; } } }