java获取指定周的第一天 和 指定周的 最后一天

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前言

做记录用：有借鉴他人代码

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获取指定周的第一天 及 指定周的 最后一天

public class WeekYearNum {


    //region 获取指定周的第一天 及 指定周的 最后一天

    /**
     * 获取指定周的第一天
     *
     * @param year
     * @param week
     * @return
     */
    public static String getFirstDayOfWeek(int year, int week) {
        if (week > 1) {
            Calendar cal = Calendar.getInstance();
            // 设置年份
            cal.set(Calendar.YEAR, year);
            // 设置周
            cal.set(Calendar.WEEK_OF_YEAR, week);
            // 设置该周第一天为星期一
            cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
            cal.setMinimalDaysInFirstWeek(0);

            cal.set(Calendar.HOUR_OF_DAY, 0);
            cal.set(Calendar.MINUTE, 0);
            cal.set(Calendar.SECOND, 0);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            return simpleDateFormat.format(cal.getTime());
        } else {
            Calendar cal = Calendar.getInstance();
            cal.set(year, 0, 1);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            return simpleDateFormat.format(cal.getTime());
        }
    }

    /**
     * 获取指定周的最后一天
     *
     * @param year
     * @param week
     * @return
     */
    public static String getLastDayOfWeek(int year, int week) {
        if (week * 7 >= 365) {  // 说明是年的最后一天
            Calendar cal = Calendar.getInstance();
            cal.set(year, 11, 31);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            return simpleDateFormat.format(cal.getTime());
        } else {
            Calendar cal = Calendar.getInstance();
            // 设置年份
            cal.set(Calendar.YEAR, year);
            // 设置周
            cal.set(Calendar.WEEK_OF_YEAR, week);
            // 设置该周第一天为星期一
            cal.setFirstDayOfWeek(Calendar.MONDAY);
            // 设置最后一天是星期日
            cal.set(Calendar.DAY_OF_WEEK, cal.getFirstDayOfWeek()   6); // Sunday
            cal.set(Calendar.HOUR_OF_DAY, 23);
            cal.set(Calendar.MINUTE, 59);
            cal.set(Calendar.SECOND, 59);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            return simpleDateFormat.format(cal.getTime());
        }
    }
    //endregion

    public static void main(String[] args) {
        Integer year = 2024;
        for (int i = 1; i <= 53; i  ) {
            System.out.println(i   "："   getFirstDayOfWeek(year, i)   "   "   getLastDayOfWeek(year, i));
        }
    }
}

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