Extract ip addresses from Strings using regex

Question

In an application, I get strings containing IP Addresses but these string have no precise format. All we know is that these strings may contain an IP address.

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Answer 1

IPV4_PATTERN = "^(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}$"

Answer 2

Check this solution to validate both IPV4 & IPV6 addresses.

/**
 * This class provides a variety of basic utility methods that are not
 * dependent on any other classes within the org.jamwiki package structure.
 */
public class Utilities {
  private static Pattern VALID_IPV4_PATTERN = null;
  private static Pattern VALID_IPV6_PATTERN = null;
  private static final String ipv4Pattern = "(([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.){3}([01]?\\d\\d?|2[0-4]\\d|25[0-5])";
  private static final String ipv6Pattern = "([0-9a-f]{1,4}:){7}([0-9a-f]){1,4}";

  static {
    try {
      VALID_IPV4_PATTERN = Pattern.compile(ipv4Pattern, Pattern.CASE_INSENSITIVE);
      VALID_IPV6_PATTERN = Pattern.compile(ipv6Pattern, Pattern.CASE_INSENSITIVE);
    } catch (PatternSyntaxException e) {
      //logger.severe("Unable to compile pattern", e);
    }
  }

  /**
   * Determine if the given string is a valid IPv4 or IPv6 address.  This method
   * uses pattern matching to see if the given string could be a valid IP address.
   *
   * @param ipAddress A string that is to be examined to verify whether or not
   *  it could be a valid IP address.
   * @return <code>true</code> if the string is a value that is a valid IP address,
   *  <code>false</code> otherwise.
   */
  public static boolean isIpAddress(String ipAddress) {

    Matcher m1 = Utilities.VALID_IPV4_PATTERN.matcher(ipAddress);
    if (m1.matches()) {
      return true;
    }
    Matcher m2 = Utilities.VALID_IPV6_PATTERN.matcher(ipAddress);
    return m2.matches();
  }
}

source: Determine if the given string is a valid IPv4 or IPv6 address.

Answer 3

IP Address Regular Expression Pattern:

^([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.
([01]?\\d\\d?|2[0-4]\\d|25[0-5])\\.([01]?\\d\\d?|2[0-4]\\d|25[0-5])$

For reference with examples click here

Answer 4

Richard's link helped me find the answer. here's the working code :

String IPADDRESS_PATTERN = 
        "(?:(?: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]?)";

Pattern pattern = Pattern.compile(IPADDRESS_PATTERN);
Matcher matcher = pattern.matcher(ipString);
if (matcher.find()) {
    return matcher.group();
} else{
    return "0.0.0.0";
}