在Java中扩展日历 [英] Extending Calendar in Java

问题描述

我想从java.util.Calendar添加更多方法到日历，但是我在使用getInstance方法时遇到问题。

I wanted to add more methods to the Calendar from java.util.Calendar, but I'm having trouble using the getInstance method.

如果我有一个对象like：

public class DateObject extends Calendar {//这里的其他方法}

If I have an object like:
public class DateObject extends Calendar{ // other methods here }

我做 DateObject mon = DateObject.getInstance（）;
代码不工作。即使我用Calendar.getInstance（）替换它，我不能将日历转换为我的DateObject。

And I do DateObject mon = DateObject.getInstance(); The code does not work. Even if I replace it with Calendar.getInstance(), I can't convert a Calendar to my DateObject.

如何使我的DateObject使用getInstance（）？

How do I make my DateObject use getInstance()?

推荐答案

getInstance（）是日历。您不能覆盖静态方法。您需要提供自己的方法。

getInstance() is a static method on Calendar. You cannot override static methods. You will need to provide your own method.

但我会质疑扩展日历的设计。你几乎肯定会更好地服务，让你的类包装一个日历，而不是扩展它。特别是，更改您的日历实施将变得非常，非常困难。

But I would question the design of extending Calendar. You will almost certainly be better served by having your class wrap a Calendar rather than extend it. In particular, changing your calendar implementation will become very, very difficult.

还要考虑到，日历API在许多方面是非常破坏，因此永远是

Consider also, that the Calendar API is very broken in a number of respects, so perpetuating it would be a crime against baby kittens.

您是否考虑过可能已经包含所需功能的替代日期/时间/日历库？例如 JodaTime 。

Have you considered an alternative date/time/calendar library which might already contain the functionality you want? For example JodaTime.

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