Date和Calendar相互转换

Date和Calendar相互转换

SimpleDateFormat dateFormat1 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        SimpleDateFormat dateFormat2 = new SimpleDateFormat("YYYY-MM-dd HH:mm:ss");

        Calendar instance = Calendar.getInstance();
        instance.set(2019,11,31);
        Date time = instance.getTime();
        System.out.println("当前时间："+time);
        System.out.println("yyyy-MM-dd HH:mm:ss    "+dateFormat1.format(instance.getTime()));
        System.out.println("YYYY-MM-dd HH:mm:ss    "+dateFormat2.format(time));

        instance.setTime(time);
//        System.out.println(instance);
        int day_of_week = instance.get(Calendar.DAY_OF_WEEK);
        System.out.println("day_of_week: "+day_of_week);