Java中自定义当前的系统时间去计算年龄demo

public static void main(String[] args) {
        // 创建出生日期对象
//       获取当前系统时间
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        System.out.println("当前系统时间：" + sdf.format(cal.getTime()));

        // 设置自定义的日期
        cal.set(Calendar.YEAR, 2023);
        cal.set(Calendar.MONTH, Calendar.MARCH);
        cal.set(Calendar.DAY_OF_MONTH, 1);
        System.out.println("自定义当前系统日期：" + sdf.format(cal.getTime()));


        String idCard = "383293196402299012";
        // 截取生日部分
        int birthYear = Integer.parseInt(idCard.substring(6, 10)); // 截取出生年份
        int birthMonth = Integer.parseInt(idCard.substring(10, 12)); // 截取出生月份
        int birthDay = Integer.parseInt(idCard.substring(12, 14)); // 截取出生日期
        int birthDayss = Integer.parseInt(idCard.substring(6, 14)); // 截取出生日期
        System.out.println("该人的生日 = " + birthDayss);
        LocalDate birthDate = LocalDate.of(birthYear, birthMonth, birthDay);
        Period age = Period.between(birthDate, LocalDate.parse(sdf.format(cal.getTime())));
        System.out.println("该人的年龄为：" + age.getYears() + "岁 " + age.getMonths() + "个月 " + age.getDays() + "天");
    }