CatPresenter.java

CatPresenter{
  
  BehaviorSubject<List<Cat>> catsSubject = BehaviorSubject.create();
  Disposable catsDisposable;
  
 void onCreate(){
   
   someClient.subscribe( cats -> {  catsSubject.onNext(cats)  })
   
 }
  
 void onResume(){
   unsubscribe();
   catsSubject.observeOn(AndroidSchedulers.mainThread()).subscribe( cats-> view.onCatsReceived(cats) );
   
   
 }
  
  void onPause(){
    unsubscribe();
  }
  
  void unsubscribe(){
    if(catsDisposable!=null){
      catsDisposable.dispose();
      catsDisposable = null;
    }
  }
  
}

CatsFragment.java

CatsFragment{

CatsPresenter presenter;

onCreateView(...){
View v = ...;
presenter = new CatsPresenter(v)
}
 void onResume(){
  presenter.onResume();
  
   
 }
  
  void onPause(){
    presenter.onPause();
  }
  


}