Calendar.before(Object when), why Object?

Question

From the javadoc of Calendar.before(Object when):

Returns whether this Calendar represents a time before the time represented by the specified Object. This method is equivalent to:

compareTo(when) < 0

if and only if when is a Calendar instance. Otherwise, the method returns false.

Why does it accepts an Object if when someone passes something that's not a Calendar instance it returns false? Why not just accepting a Calendar instance? This kept me watching for uncorrect results in a functionality for quite some time.

Answer 1

I think there is no particular reason for that. java.util.Calendar has some design issues we have have to live with, unfortunately.

Answer 2

I think this may be to provide encapsulation by using polymorphic behaviour in the before() method.