問(wèn)題描述

我正在嘗試制作一個(gè)對(duì)象的深層副本，包括一個(gè) GregorianCalendar 實(shí)例.我總是對(duì)使用 clone() 持謹(jǐn)慎態(tài)度，而且這里似乎沒(méi)有被覆蓋，所以我只是逐個(gè)字段地進(jìn)行復(fù)制.理想情況下，會(huì)有一個(gè)復(fù)制構(gòu)造函數(shù)，我可以像這樣使用它:

I'm trying to make a deep copy of an object, including a GregorianCalendar instance. I'm always wary of using clone() and it doesn't seem to have been overridden here, so I'm just doing the copy field by field. Ideally, there'd be a copy constructor, which I could use like so:

GregorianCalendar newCalendar = new GregorianCalendar(oldCalendar);

不幸的是，我在 API 中找不到任何此類(lèi)功能，并且一直在試圖找出我需要哪些字段才能獲得準(zhǔn)確的副本.那么，要復(fù)制其中一個(gè)日歷，你會(huì)怎么做呢?我在這里錯(cuò)過(guò)了一些簡(jiǎn)單的快捷方式嗎?

Unfortunately I can't find any such functionality in the API and am stuck trying to figure out which fields I need to get an exact copy. So, to make a copy of one of these calendars, how would you do it? Am I missing some simple shortcut here?

推薦答案

java.util.Calendar 已經(jīng)覆蓋了正在工作的 clone()，所以使用它.此外，Calendar 沒(méi)有很深的數(shù)據(jù)層次——它的數(shù)據(jù)主要是 ints.

java.util.Calendar has overridden clone() which is working, so use it. Furthermore, Calendar doesn't have a deep data hierarchy — its data are mainly ints.

要擴(kuò)展答案，您可以調(diào)用 SerializationUtils.clone(...) (來(lái)自 Apache commons-lang)在任何進(jìn)行深拷貝的對(duì)象上，如果整個(gè)數(shù)據(jù)層次結(jié)構(gòu)實(shí)現(xiàn) Serializable.

To extend the answer, you can call SerializationUtils.clone(…) (from Apache commons-lang) on any object which makes a deep copy, if the whole data hierarchy implements Serializable.

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