如何将一个月添加到日期并获得同一天 [英] How to add one month to a date and get the same day

问题描述

我尝试根据工作日添加一个月的日期。例如，日期是9月的星期一。添加后我想要有10月的星期一。
我试图在下一个日期添加一个月

I try to add one month to a date depending on weekdays. Fore example the date is the 3. Monday of September. After adding I want have the 3. Monday of October. I tried to add one month to following date

Mon Sep 17 17:30:00 MESZ 2012

使用此代码：

Calendar date = Calendar.getInstance();
date.setTimeInMillis(date_in_mil);
date.add(Calendar.DAY_OF_WEEK_IN_MONTH, 3); 

但我得到了

Mon Oct 08 17:30:00 MESZ 2012

这是第二个星期一十月而不是第三。有没有人知道这是如何工作的？

which is the second Monday of Oct and not the third. Has anybody an idea how this workes?

编辑
这是我在下面的答案中使用的解决方案：

EDIT This is the solution I used like in the answer below:

int prevDayOfWeek = date.get(Calendar.DAY_OF_WEEK);
date.add(Calendar.MONTH, 1);
date.set(Calendar.DAY_OF_WEEK, prevDayOfWeek);
date.set(Calendar.DAY_OF_WEEK_IN_MONTH, week);

周数是一个月内的周数。前例1表示第一个，第二个表示第二个，依此类推。但是周也可以倒数，例如-1表示月的最后一周。

wereby week is the number of the week in a month. Fore example 1 means the first, 2 the second, and so on. But week can also count backwards, fore example -1 means the last week of month.

推荐答案

如果你想得到第3个星期一月，然后使用
设置而不是添加

date.set（Calendar.DAY_OF_WEEK_IN_MONTH，3）;

If you want get 3rd monday of month, then use set instead of add
date.set(Calendar.DAY_OF_WEEK_IN_MONTH, 3);

如果你想在当前日期加一个月，请使用

date.add（Calendar.MONTH，1）;

if you want add one month to current date, use
date.add(Calendar.MONTH, 1);

编辑

final Calendar date = Calendar.getInstance();
date.set(2012, Calendar.SEPTEMBER, 17);

int prevDayOfWeekInMonth = date.get(Calendar.DAY_OF_WEEK_IN_MONTH);
int prevDayOfWeek = date.get(Calendar.DAY_OF_WEEK);

date.add(Calendar.MONTH, 1);
date.set(Calendar.DAY_OF_WEEK, prevDayOfWeek);
date.set(Calendar.DAY_OF_WEEK_IN_MONTH, prevDayOfWeekInMonth);

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