如何在 Java 中对日期执行算术运算？

How can I perform arithmetic operation with dates in Java?

提问by AndroidDev

Possible Duplicate:
How to calculate time difference in java?

可能的重复：
如何计算 Java 中的时差？

Actually I want to subtract two dates in Java. I tried a lot but can't succeed. So anyone please help me.

其实我想在Java中减去两个日期。我尝试了很多，但无法成功。所以请任何人帮助我。

Date dtStartDate=pCycMan.getStartDate();

Date dtEndDate=pCycMan.getEndDate();

How can I subtract these two Dates?

我怎样才能减去这两个日期？

采纳答案by Mike Deck

long msDiff = dtEndDate.getTime() - dtStartDate.getTime()

msDiffnow holds the number of milliseconds difference between the two dates. Feel free to use the division and mod operators to convert to other units.

msDiff现在保存两个日期之间的毫秒数差异。随意使用除法和 mod 运算符转换为其他单位。

回答by aioobe

how can i subtract these two Dates?

我怎样才能减去这两个日期？

You can get the difference in milliseconds like this:

您可以像这样获得以毫秒为单位的差异：

dtEndDate.getTime() - dtStartDate.getTime()

(getTimereturns the number of milliseconds since January 1, 1970, 00:00:00 GMT.)

（getTime返回自 1970 年 1 月 1 日格林威治标准时间 00:00:00 以来的毫秒数。）

However, for this type of date arithmetics the Joda time library, which has proper classes for time durations (Duration) is probably a better option.

然而，对于这种类型的日期算术，Joda 时间库，它具有适当的持续时间类 ( Duration) 可能是更好的选择。

回答by nicholas.hauschild

Use the Calendarclass.

使用日历类。

Usage:

用法：

Calendar c = Calendar.getInstance();
c.setTime(dtStartDate);
int date = c.get(Calendar.YEAR); //int represents the year of the date
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK); // int represents dayOfWeek as defined in link.

回答by marchaos

Create two Calendarobjects from those Dates and then use the add() method (which can be used to subtrade dates too).

从这些日期创建两个日历对象，然后使用 add() 方法（也可用于对日期进行子交易）。

回答by rascio

There is a framework to work with the date in java... http://joda-time.sourceforge.net/userguide.htmltake a look, i'm sure that it can help you

有一个框架可以处理java中的日期...... http://joda-time.sourceforge.net/userguide.html看看，我相信它可以帮助你

回答by RMT

To substract to dates you can get them both as longs getTime()and subtract the values that are returned.

要减去日期，您可以将它们作为 long 获取getTime()并减去返回的值。

回答by Bala R

long diffInMillis = dtEndDate.getTimeInMillis() -  dtStartDate.getTimeInMillis();

回答by AlexR

It depends what do you want. To get difference in milliseconds say dtStartDate.getTime() - dtEndDate.getTime().

这取决于你想要什么。要获得以毫秒为单位的差异，请说dtStartDate.getTime() - dtEndDate.getTime()。

To get difference in days, hours etc use Calendar class (methods like after, before, compareTo, roll may help).

要获得天数、小时数等的差异，请使用 Calendar 类（诸如 after、before、compareTo、roll 之类的方法可能会有所帮助）。