Does RxJava2 auto dispose observable when they call completed or error?

I have a question about the disposal on RxJava. I found this below sentence on RxSwift document on Github.

When a sequence sends the completed or error event all internal resources that compute sequence elements will be freed.

To cancel production of sequence elements and free resources immediately, call dispose on the returned subscription.

if I understand correctly the resources (observables) will be freed after they call onCompleted or onError.

So the question is, does RxJava do the same thing like RxSwift or I need to call the dispose by myself?