setFirstDayOfWeek in Calendar 不起作用，失效，不能用

在使用Calendar的时候，往往因为国外和中国的习惯不同，而造成迥异。比如，老外习惯周日作为每周的起始第一天，而中国习惯用周一作为每周的起始第一天。

我看见Calendar的API里面有?setFirstDayOfWeek()。

所以我设置setFirstDayOfWeek(Calendar.MONDAY)

但是发现使用cal.get(Calendar.DAY_OF_WEEK)得到的，还是以周日为起始第一天的结果。很是郁闷。上网找了，老外也有遇到这个问题的。老外遇到的问题：

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Compare this to the API for?WEEK_OF_MONTH?and?WEEK_OF_YEAR, which?do?say that they depend on the first day of the week. You can?test?to see if this works correctly for your purposes.

If you really need a number representing day of week with 1 meaning Monday and 7 meaning Sunday, you can get it with a tiny bit of math:
public int getDayOfWeek(String dateString){SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");try {Date date = format.parse(dateString);Calendar cal = Calendar.getInstance();cal.setTime(date);cal.setFirstDayOfWeek(Calendar.MONDAY);int tmp = cal.get(Calendar.DAY_OF_WEEK) - 1;if (0 == tmp) {tmp = 7;}return tmp;} catch (ParseException e) {e.printStackTrace();return -1;}}?下面是链接：?http://www.coderanch.com/t/381293/java/java/setFirstDayOfWeek-Calendar