LiveDataReactiveStreams: converting Flowable to LiveData doesn't work

Question

I'm trying to convert a Flowable into LiveData and observing it in the activity. My Flowable is emitting values with a constant delay , but the LiveData which i'm converting this Flowable to, is not at all receiving any values in its observer. I have created a sample code to demonstrate the problem

Activity

    public class MyrActivity extends AppCompatActivity {

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_my);
            MyViewModel myViewModel = ViewModelProviders.of(this).get(MyViewModel.class);
            myViewModel.init();
            myViewModel.getListLiveData().observe(this, new Observer<List<String>>() {
                @Override
                public void onChanged(@Nullable List<String> strings) {
                    Timber.d("value received in live data observer: %s", strings);
                    // This callback never get called
                    for (String string : strings) {
                        Timber.d(string);
                    }
                }
            });

        }
    }

ViewModel class

     static class MyViewModel extends ViewModel{
            LiveData<List<String>> mListLiveData;
            PublishProcessor<String> mStringPublishProcessor = PublishProcessor.create();

            public void init() {
                mListLiveData = LiveDataReactiveStreams.fromPublisher(mStringPublishProcessor.toList().toFlowable());

                // This is to trigger the mStringPublishProcessor on constant intervals
                Observable.interval(0,5,TimeUnit.SECONDS)
                        .map(aLong -> {
                            Timber.d("value emitted: ");  // this log is showing as expected
                            mStringPublishProcessor.onNext("Value "+aLong);
                            return aLong;
                        }).subscribe();
            }

            public LiveData<List<String>> getListLiveData() {
                return mListLiveData;
            }
        }

Now , in my activity I can see only the logs from the Observable.interval

     com.example.app D/MyActivity$MyViewModel: value emitted: 
     com.example.app D/MyActivity$MyViewModel: value emitted: 
     com.example.app D/MyActivity$MyViewModel: value emitted: 
     com.example.app D/MyActivity$MyViewModel: value emitted: 
     com.example.app D/MyActivity$MyViewModel: value emitted: 
     com.example.app D/MyActivity$MyViewModel: value emitted: 

Why the LiveData observer never received any values from the Flowable?

as per the documentation of LiveDataReactiveStreams.fromPublisher

Creates an Observable stream from a ReactiveStreams publisher. When the LiveData becomes active, it subscribes to the emissions from the Publisher.

Answer 1

.toList() will map the return only after onComplete() call. In your example, the completion is never called.