public class DateCa {        public static void main(String[] args) throws ParseException {                /** 时间操作首推Calendar 格里高利历 **/        Calendar ca =  Calendar.getInstance();        //获取日期的单个属性:年,月,周,日,时,分        System.out.println(ca.get(Calendar.YEAR));        System.out.println(ca.get(Calendar.MONTH));//获取月份从0开始        System.out.println(ca.get(Calendar.WEEK_OF_YEAR));        System.out.println(ca.get(Calendar.DAY_OF_MONTH));        System.out.println(ca.get(Calendar.HOUR_OF_DAY));        System.out.println(ca.get(Calendar.MINUTE));        //日期操作        ca.add(Calendar.YEAR, 2);//退后两年        System.out.println(ca.get(Calendar.YEAR));        ca.add(Calendar.MONTH, 2);//退后两月        System.out.println(ca.get(Calendar.MONTH));        ca.add(Calendar.DAY_OF_MONTH, 10);//退后两天        System.out.println(ca.get(Calendar.DAY_OF_MONTH));                //直接设置所需时间        ca.set(Calendar.YEAR,100);//将给定的日历字段设置为给定值。        System.out.println(ca.get(Calendar.YEAR));        ca.set(2018, 7, 12);        System.out.println(ca.get(Calendar.YEAR));        System.out.println(ca.get(Calendar.MONTH));        System.out.println(ca.get(Calendar.DAY_OF_MONTH));                //时间比较推荐        System.out.println(ca.after(new Date()));        System.out.println(ca.before(new Date()));        //也可以获取指定时区的时间系统        System.out.println(Calendar.getInstance(Locale.ENGLISH));                /** 其他时间操作**/        //当前秒数        System.out.println(System.currentTimeMillis());        System.out.println(new Date().getTime());        //时间格式化        SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");        System.out.println(sf.format(ca.getTime()));        System.out.println(sf.parse("2018-10-12 09:18:23").after(new Date()));    }}