java 根据某个日期查询出是某年的第几周

前言

做记录用：

一、java根据某个日期查询出是某年的第几周

public class WeekByDate {
    public static void main(String[] args) throws ParseException {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
//        String time = "2023-12-25";
        String time = "2022-01-06";
        Date parse = simpleDateFormat.parse(time);
        Calendar calendar = Calendar.getInstance();
        //设置星期一为一周开始的第一天
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        //设置在一年中第一个星期所需最少天数
        calendar.setMinimalDaysInFirstWeek(0);
        calendar.setTime(parse);
        int week = calendar.get(Calendar.WEEK_OF_YEAR);
        System.out.println(week);
        if (week == 1 && parse.getMonth() == 11) {
            calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - 7);
            Date pastDate = calendar.getTime();
            String result = simpleDateFormat.format(pastDate);
            System.out.println(result);
            week = calendar.get(Calendar.WEEK_OF_YEAR) + 1;
            System.out.println(week);
        }
    }

}