因为语言写作比看起来要难得多，特别是处理时间比大多数人想象的要难得多。关于这个问题的一小部分(在现实中，不是Java)，请参阅YouTube视频“时间和时区的问题-计算机爱好者”，网址是https://www.youtube.com/watch?v=-5wpm-gesOY。如果你在困惑中笑掉了头，不要感到惊讶。

因为所有东西都是从0开始的。这是Java编程的一个基本事实。如果有一件事偏离了这一点，那么就会导致一系列的混乱。让我们不要争论它们的构成和代码。

设置月份为“日历”。MARCH，或者比较，看看它是否== Calendar。比如六月。

Date和Calendar类可以追溯到Java的早期，当时人们还在摸索，它们被广泛认为设计得不是很好。

如果今天用相同的设计创建Calendar，而不是int类型的Calendar。JUNE等等，他们会用枚举。

对我来说，没有人比mindpro.com更能解释这一点:

Gotchas java.util.GregorianCalendar has far fewer bugs and gotchas than the old java.util.Date class but it is still no picnic. Had there been programmers when Daylight Saving Time was first proposed, they would have vetoed it as insane and intractable. With daylight saving, there is a fundamental ambiguity. In the fall when you set your clocks back one hour at 2 AM there are two different instants in time both called 1:30 AM local time. You can tell them apart only if you record whether you intended daylight saving or standard time with the reading. Unfortunately, there is no way to tell GregorianCalendar which you intended. You must resort to telling it the local time with the dummy UTC TimeZone to avoid the ambiguity. Programmers usually close their eyes to this problem and just hope nobody does anything during this hour. Millennium bug. The bugs are still not out of the Calendar classes. Even in JDK (Java Development Kit) 1.3 there is a 2001 bug. Consider the following code: GregorianCalendar gc = new GregorianCalendar(); gc.setLenient( false ); /* Bug only manifests if lenient set false */ gc.set( 2001, 1, 1, 1, 0, 0 ); int year = gc.get ( Calendar.YEAR ); /* throws exception */ The bug disappears at 7AM on 2001/01/01 for MST. GregorianCalendar is controlled by a giant of pile of untyped int magic constants. This technique totally destroys any hope of compile-time error checking. For example to get the month you use GregorianCalendar. get(Calendar.MONTH)); GregorianCalendar has the raw GregorianCalendar.get(Calendar.ZONE_OFFSET) and the daylight savings GregorianCalendar. get( Calendar. DST_OFFSET), but no way to get the actual time zone offset being used. You must get these two separately and add them together. GregorianCalendar.set( year, month, day, hour, minute) does not set the seconds to 0. DateFormat and GregorianCalendar do not mesh properly. You must specify the Calendar twice, once indirectly as a Date. If the user has not configured his time zone correctly it will default quietly to either PST or GMT. In GregorianCalendar, Months are numbered starting at January=0, rather than 1 as everyone else on the planet does. Yet days start at 1 as do days of the week with Sunday=1, Monday=2,… Saturday=7. Yet DateFormat. parse behaves in the traditional way with January=1.

我想说是懒惰。数组从0开始(每个人都知道);一年中的月份是一个数组，这让我相信Sun的一些工程师只是懒得在Java代码中加入这个小细节。

java.time.Month

Java为您提供了另一种使用基于1的索引的方法。使用java.time.Month enum。为12个月中的每个月预定义一个对象。他们在1月到12月之间分别有1-12号;调用getValue获取该号码。

利用Month。七月(给你7分) 而不是日历。七月(给你6分)。

(import java.time.*;)