Is calling Java's Calendar.getTime() necessary to update the object?

Question

I came across a comment in some java code that states that getTime() needs to be called to update the Calendar object. Is this true? I cannot find anything that says that this is necessary.

Here's the code:

Calendar cal = new GregorianCalendar();
cal.setFirstDayOfWeek(Calendar.SUNDAY);
cal.set(2009, 9 - 1, 10, 2, 30);
// Get Time needs to be called to update the Calendar object
cal.getTime();

Answer 1

No, this is not true.

Answer 2

No, it should not be necessary.

Was the Calendar serialized immediate afterwards?

I've been caught by a bug with Calendar serialization in older jvms.

Bug parade bug #4328747

Calling getTime before serialization may be enough to get around the bug, although I don't have a sufficiently old JVM installed for me to confirm that.

Answer 3

You could be hitting Bug ID 4851640

Calling get(...) / getTime() on a Calendar instance makes isSet(...) useless!