获取某一年的第一天和某一年的最后一天

public static Integer getYearForNum(int num) {
    Calendar now = Calendar.getInstance();
    int year = now.get(1);
    int date = year - num;
    return date;
}

public String getYearFirst(int num) {
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
    Calendar calendar = Calendar.getInstance();
    Integer yearForNum = DateUtil.getYearForNum(0);
    System.out.println(yearForNum);
    calendar.clear();
    calendar.add(Calendar.YEAR, yearForNum-1970-num);
    Date currYearFirst = calendar.getTime();
    String format = simpleDateFormat.format(currYearFirst);
    return format;

}


public String getYearLast(int num) {
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
    Calendar calendar = Calendar.getInstance();
    calendar.clear();
    Integer yearForNum = DateUtil.getYearForNum(num);
    calendar.set(Calendar.YEAR, yearForNum);
    calendar.roll(Calendar.DAY_OF_YEAR, -1);
    Date currYearLast = calendar.getTime();
    String format = simpleDateFormat.format(currYearLast);

    return format;

}