java根据日期获取当天是周几

  /**
     * 根据日期获取当天是周几
     * @param datetime 日期
     * @return 周几
     */
    public static String dateToWeek(String datetime) {
    
    
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String[] weekDays = {
    
    "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"};
        Calendar cal = Calendar.getInstance();
        Date date;
        try {
    
    
            date = sdf.parse(datetime);
            cal.setTime(date);
        } catch (ParseException e) {
    
    
            e.printStackTrace();
        }
        int w = cal.get(Calendar.DAY_OF_WEEK) - 1;
        return weekDays[w];
    }