java 上个月的周数

Question

在java中如何获得上个月的周数，从星期一开始的周

cal.setFirstDayOfWeek(Calendar.MONDAY);

cal 是 Calendar 实例

如果一周的第一天不是星期一，则返回 0。所以上周必须算作前几个月，这是我的要求。

Answer 1

您的问题不是很清楚，但您可能正在寻找这样的内容:

Calendar cal = Calendar.getInstance();
cal.setTime(new Date()); // today's date
// previous month from today
cal.add(Calendar.MONTH, -1);
// get to the 1st week
cal.add(Calendar.DATE, -7 * (cal.get(Calendar.DAY_OF_MONTH)/7));
// Get to the 1st Mon of last month
cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
// # of days in last month
int maxDay = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
// print # of week since Mon of last month
int numWeeks = ((maxDay-cal.get(Calendar.DATE))/7)+1;
System.out.printf("# of weeks from Mon in last month: %d%n", numWeeks);