Do we need to call onComplete() of subject in onDestroy() method of activity ? about rxkotlin HOT 2 OPEN

For what? If you haven't supposed to do anything on onComplete on the observer you don't need to do that.

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onComplete is used to indicate that current streams has finished in emitting the data. When your code has finished emitting all the data needed for the observer, then you should call onComplete for this use case to notify the observer. For me, dispose?.dispose() is enough as it already unsubscribe the subscription to prevent any callback on destroyed activity.

Here's references to help you:

1. https://blog.mindorks.com/understanding-rxjava-subject-publish-replay-behavior-and-async-subject-224d663d452f
2. http://reactivex.io/RxJava/javadoc/rx/subjects/PublishSubject.html

from rxkotlin.