得到某一天是星期几

得到某一天是星期几

//获取yyyy-MM-dd是星期几
public static int getWeekdayOfDateTime(String datetime){
   DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
   Calendar c = Calendar.getInstance();  
      try {
  c.setTime(df.parse(datetime));
   } catch (Exception e) {
  e.printStackTrace();
   }
   int weekday = c.get(Calendar.DAY_OF_WEEK)-1;
   return weekday;
}