public static String randomNumberString(int length) {
        char[] chars = "0123456789".toCharArray();
        return RandomStringUtils.random(length, 0, 9, false, false, chars);
    }
public static String randomNumberString ( int length ) { char [ ] chars = "0123456789" . toCharArray ( ) ; return RandomStringUtils . random ( length , 0 , 9 , false , false , chars ) ; }
random number string with zero possible in any position

@param length of number string
@return number string