get day of programmer by using Russia Julian

/**
 * get day of programmer by using Russia Julian Calendar
 * 256th day of the programmer input year
 * output data format: dd.mm.yyyy
 * 儒略历从三月March到一月January，
 * 各月的天数依次为31、30、31、30、31、30、31、30、31、30、31；
 * 二月February的天数为平年29、闰年30，四年一闰
 * @param year
 * @return
 */
public static String dayOfProgrammerJulian(int year) {
    if(!checkIsJulianYear(year)){
        return null;
    }
    //

    return null;
}
/**
 * check year if is leap year
 *
 * @param year
 * @return
 */
public static Boolean checkIsLeapYear(int year) {
    if (year < 1700 || year > 2700) {
        return null;
    }
    if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
        return true;
    }
    return false;
}

/**
 * check year if it is Russia Julian Calendar
 *
 * @param year
 * @return
 */
public static Boolean checkIsJulianYear(int year) {
    if (year < 1700 || year > 2700) {
        return null;
    }
    if (year >= 1700 && year <= 1917) {
        return true;
    }
    return false;
}

/**
 * check year if it is Russia Greborian Calendar
 *
 * @param year
 * @return
 */
public static Boolean checkIsGregorianYear(int year) {
    if (year < 1700 || year > 2700) {
        return null;
    }
    if (year > 1918 && year <= 2700) {
        return true;
    }
    return false;
}

/**
 * check year if it is Russia special transmition year
 *
 * @param year
 * @return
 */
public static Boolean checkIsRussiaSpecialTransitionYear(int year) {
    if (year < 1700 || year > 2700) {
        return null;
    }
    if (year == 1918) {
        return true;
    }
    return false;
}