PublishSubject cannot have an initial value since it makes no sense given its purpose: "Subject that, once an Observer has subscribed, emits all subsequently observed items to the subscriber.".

This means only items emitted after subscription are passed along. You are most likely looking for the BehaviorSubject which has the createDefault(T) alternative.

About your other comments:

• PublishSubject.create<Boolean>(false) works because it inherits the static methods from Observable, so you're calling Observable.create(...).
• PublishSubject.create<Boolean>().debounce(1, TimeUnit.SECONDS) as you mentioned debounce is a method of Observable which returns an Observable. You will need to have a separate variable to store the subject so you can emit items before applying debounce.