Objects Without Behaviour

Question

I have a question related to general OOP than specific to a language. I was trying out a simple application (in java) and I was trying to model it like a real world scenario. Wh

Answer 1

Short answer:

is it a bad oo practice to have such objects

Not necessarily, but it depends on the context.

Longer answer:

I have a question related to general OOP than specific to a language. I was trying out a simple application (in java) and I was trying to model it like a real world scenario.

There really isn't any rule stating that you should. In fact, I know of quite a few people who frown upon that statement, Uncle Bob Martin for one. It's more about modelling business processes than it is to model "real world scenarios". I've tried that in the past, and found there's no - or almost no - benefit to get from rigidly trying to model everything as it is in the real world. If anything, I think it makes your application more complex, and the more complex software becomes, the harder it becomes to maintain.

While re-factoring I realized that I came up with a simple object that just has one member and an overridden equals and hashcode.

Might be okay, as @Arseny already said, the ValueObject is a well-known way of working, although I usually don't end up with a lot of them when I write code. If more than a few of your objects doesn't have any behaviour, this might be an indication of a so-called Anemic Domain Model, which you have to be careful for (more complexity at no apparent benefit).

You can find out if you're "doing it wrong" (with variable values of "wrong", of course): just see what the collaborators are doing with your ValueObject, and see if there's anything there that resembles a calculation which actually belongs to the object itself.

However, if this is one of the few objects that doesn't contain any behaviour: well, yeah, that happens and you probably don't have to worry about it. We'd have to see some code to be conclusive in our anwers though.