Validate_IP_Addess.java

class Solution {

  public String validateIPv4(String IP) {
    String[] nums = IP.split("\\.", -1);

    for (String x : nums) {
      if (x.length() == 0 || x.length() > 3) return "Neither";

      if (x.charAt(0) == '0' && x.length() != 1) return "Neither";

      for (char ch : x.toCharArray()) {
        if (!Character.isDigit(ch)) return "Neither";
      }
      
      if (Integer.parseInt(x) > 255) return "Neither";
    }

    return "IPv4";
  }

  public String validateIPv6(String IP) {
    
    String[] nums = IP.split(":", -1);
    String hexdigits = "0123456789abcdefABCDEF";
    
    for (String x : nums) {
    
      if (x.length() == 0 || x.length() > 4) return "Neither";
    
      for (Character ch : x.toCharArray()) {
        if (hexdigits.indexOf(ch) == -1) return "Neither";
      }
    }
    return "IPv6";
  }

  public String validIPAddress(String IP) {
    if (IP.chars().filter(ch -> ch == '.').count() == 3) {
      return validateIPv4(IP);
    } else if (IP.chars().filter(ch -> ch == ':').count() == 7) {
      return validateIPv6(IP);
    } else return "Neither";
  }
}