Regex Grouping Using The IP Address Example

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexGroupsIPAddress {
    public static void main(String args[]) {

        // String to be scanned to find the pattern.
        String line = "123.234.212.97     134.241.99.445";
        String pattern = "(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})";

        // Create a Pattern object
        Pattern r = Pattern.compile(pattern);

        // Now create matcher object.
        Matcher m = r.matcher(line);
        while (m.find()) {
            int bitValue = 0;
            for (int i = 1; i <= 4; i++) {
                int octet = Integer.parseInt(m.group(i));
                if (octet >= 0 && octet <= 255) {
                    bitValue = (bitValue << 8) + octet;
                } else {
                    bitValue = -1;
                    break;
                }
            }
            if (bitValue >= 0) {
                System.out.println("Valid IP Address Found: " + m.group(0)
                        + "; BitValue = " + bitValue);
            } else {
                System.out.println("Illegal IP Address Found: " + m.group(0));
            }
        }
    }
}