使用Java中的Calendar的add（）方法添加30天以上 [英] add more than 30 days with Calendar's add() method in Java

问题描述

我不太确定在向Java Calendar对象添加超过30天时使用的字段。 Calendar.DAY_OF_MONTH 和 Calendar.DAY_OF_YEAR 之间有什么区别吗？

I'm not quite sure what field to use when adding more than 30 days to a Java Calendar object. Is there any difference in between Calendar.DAY_OF_MONTH and Calendar.DAY_OF_YEAR?

示例：

GregorianCalendar d = new GregorianCalendar();
d.add(Calendar.DAY_OF_YEAR, 90);

vs

GregorianCalendar d = new GregorianCalendar();
d.add(Calendar.DAY_OF_MONTH, 90);

谢谢。

推荐答案

我不认为这会产生影响，当你调用add。当你调用getter时，区别很重要。

I don't think it makes a difference when you call add. The distinction is important when you call the getters.

两种方法都很好，对吧？

Both methods work fine, right? For more than 30 days, as well as negative amounts.

GregorianCalendar＃add（确实复杂）的来源包含此部分：

The (admittedly complicated) source for GregorianCalendar#add has this section:

 case DAY_OF_MONTH: // synonym of DATE
 case DAY_OF_YEAR:
 case DAY_OF_WEEK:
    break;

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