Quickest way to clone a GregorianCalendar?

Question

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); 

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?

Answer 1

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.

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.

Answer 2

Specifically, the quickest line of code to copy a Calendar is:

GregorianCalendar newCalendar = (Calendar)(oldCalendar.clone());