Java：如何获取一个月中x天的日期（例如2012年2月的第三个星期一）

在Java中执行日期算术（通常，除了最琐碎的事情之外，还可以对日期时间做任何事情），Joda-
Time
就是这样的答案：

public static LocalDate getNDayOfMonth(int dayweek,int nthweek,int month,int year)  {   LocalDate d = new LocalDate(year, month, 1).withDayOfWeek(dayweek);   if(d.getMonthOfYear() != month) d = d.plusWeeks(1);   return d.plusWeeks(nthweek-1);}public static LocalDate getLastWeekdayOfMonth(int dayweek,int month,int year) {   LocalDate d = new LocalDate(year, month, 1).plusMonths(1).withDayOfWeek(dayweek);   if(d.getMonthOfYear() != month) d = d.minusWeeks(1);  return d;}public static void main(String[] args) {   // second wednesday of oct-2011   LocalDate d = getNDayOfMonth( DateTimeConstants.WEDNESDAY, 2, 10, 2011);   System.out.println(d);   // last wednesday of oct-2011   LocalDate dlast = getLastWeekdayOfMonth( DateTimeConstants.WEDNESDAY,  10, 2011);   System.out.println(dlast);}