Class 图 OOP

Question

If two classes are associated regularly, do they need to contain each other's objects as attributes? For example, a Post class and a Comment class on a social media platform. Should the Post class contain an array of comment objects as an attribute? And should the Comment class contain a post object as an attribute?

Answer 1

This is a common mistake of redundant information. It does not need to be shown in the class diagram as a field because it is derived from the association.
This is a class diagram that covers what you have mentioned in its simplest form.

As you can see, objects for each class do not need to be added as fields.