RxAndroid-BehaviorSubject在onNext上不发出

Question

I am trying to learn RXJava with MVVM pattern.

Here is scenario I am trying to implement:

On some search event I am calling SearchViewModel.handleSearchTopic() which is emitting list but somehow it is not getting caught in observer's onNext event. Subscription is also happening successfully. I think I am doing some simple mistake, please point that. Also, is there any better way of implementing this use case?

SearchViewModel.java

private final BehaviorSubject<List<Topic>> topicList = BehaviorSubject.create();

public void handleSearchTopic() {
    List<Topic> list = //getsomehow;
    topicList.onNext(list);
}

public Observable<List<Topic>> getTopicListObservable() {
    return topicList.asObservable();
}

Fragment.java

@NonNull
private CompositeSubscription subscription;

@NonNull
private SearchViewModel searchViewModel;

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    searchViewModel = new SearchViewModel();
    bind();
}

@Override
public void onDestroy() {
    unBind();
    super.onDestroy();
}

private void bind() {
    subscription = new CompositeSubscription();

    subscription.add(searchViewModel.getTopicListObservable()
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Observer<List<Topic>>() {
                @Override
                public void onCompleted() {
                    //do something
                }

                @Override
                public void onError(Throwable e) {
                    //do something

                }

                @Override
                public void onNext(List<Topic> topics) {
                    //ideally this should be called when event is emitted but not getting called

                }
            }));

}

private void unBind() {
    subscription.unsubscribe();
}

Answer 1

It was a stupid mistake. I was using different instances of SearchViewModel in fragment and search event.