Is it a bad practice to include non-public fields into equals() [closed]

Question

Is it a bad practice to include fields inaccessible by any public methods (and which themselves are not and can not be derived from any other public fields) into equals() ?

What are possible bad consequences of doing so?

Is this described as a bad practice somewhere? (I assume hash/equals contract is ok)

I feel, such equals would be philosophically very wrong. Such equals is not observed in the world. But can it lead to real programming misbehavior, philosophy aside?

Answer 1

It's absolutely fine and sometimes necessary. The only fields that you shouldn't compare are ones marked as transient.

I'd assert that two instances are equal if and only if their serialisations are equal. That's why transient matters and the degree of field encapsulation doesn't.