Проверьте адрес IPv4 в Java

/**
 * Check if ip is valid
 *
 * @param ip to be checked
 * @return <tt>true</tt> if <tt>ip</tt> is valid, otherwise <tt>false</tt>
 */
private static boolean isValid(String ip) {
    String[] bits = ip.split("\\.");
    if (bits.length != 4) {
        return false;
    }
    for (String bit : bits) {
        try {
            if (Integer.valueOf(bit) < 0 || Integer.valueOf(bit) > 255) {
                return false;
            }
        } catch (NumberFormatException e) {
            return false; /* contains other other character */
        }
    }
    return true;
}

Получают допустимый IP-адрес в двух строках с помощью Регулярного выражения , проверьте сессию комментария кода, как регулярное выражение работает для получения диапазона числа.

public class regexTest {


    public static void main(String[] args) {
        String IP = "255.001.001.255";
        System.out.println(IP.matches(new MyRegex().pattern));
    }

    }

    /*
    * /d - stands for any number between 0 to 9
    * /d{1,2} - preceding number that 0 to 9 here , can be of 1 digit to 2 digit . so minimum 0 and maximum 99
    * |  this stands for or operator
    *
    * () this is applied on a group to get the single value of outcome
    * (0|1)\d{2} = first digit is either 0 or 1 and other two digits can be any number between ( 0 to 9)
    * 2[0-4]\d - first digit is 2 , second digit can be between 0 to 4 and last digit can be 0 to 9
    * 25[0-5] - first two digit will be 25 and last digit will be between 0 to 5
    *
    * */
    class MyRegex {

        String zeroTo255 = "(\\d{1,2}|(0|1)\\d{2}|2[0-4]\\d|25[0-5])";
        public String pattern =  zeroTo255 + "\\." + zeroTo255 + "\\." + zeroTo255 + "\\." + zeroTo255;;

    }