Strange behaviour with GregorianCalendar

Question

I just encountered a strange behaviour with the GregorianCalendar class, and I was wondering if I really was doing something bad.

This only appends when the initiali

Answer 1

I'm sure it is not wanted behavior. I'm just equally sure no one really thought that use case through when they made the class. The fact of the matter is that Calendar has a very big problem with internal state and how it manages all of the potential transitions in all the set methods.

If you can't use JodaTime or JSR-310 in your project, unit test heavily when using the Calendar class. As you can see in this case Calendar code behaves differently depending on what day of the month (or what time of the day) you run the code.