ZooListViewModel.java

public class ZooListViewModel extends BaseViewModel {

    private MutableLiveData<List<Zoo>> mZoosLiveData;

    public ZooListViewModel() {
        mZoosLiveData = new MutableLiveData<>();
        DataSubscription subscription = ZooRepository.subscribeToZooList(this::refreshZoos);
        addSubscription(subscription);
    }

    private void refreshZoos(List<Zoo> zoos) {
        mZoosLiveData.postValue(zoos);
    }

    public LiveData<List<Zoo>> getZoos() {
        return mZoosLiveData;
    }

    public void refreshZoos() {
        ZooRepository.refreshZoos();
    }
}