new.java

PublishSubject<Void> viewClickedSubject = PublishSubject.create();
CompositeSubscription startStopCompositeSubscription = new CompositeSubscription();

protected void onStart() {

   view.setOnClickListener(v-> viewClickedSubject.onNext(null));
   
   Subscription subscription = viewClickedSubject
       .flatMap(aVoid-> api.getAlert())
       .subscribe(this::makeAlertToast, Throwable::printStackTrace);

   startStopCompositeSubscription.add(subscription);
}

protected void onStop() {
   startStopCompositeSubscription.clear();
}