MVP example

MyMvpContract.java

public interface MyMvpContract {
    interface Presenter {
        void attachView(MyMvpContract.View view);
        void detachView();

        //some other code
    }

    interface View {
        //some other code
    }
    
    //some other code
}

MyPresenter.java

public class MyPresenter extends ViewModel implements
        MyMvpContract.Presenter {
        
    private MyMvpContract.View mView;
    private LiveData<List<Event>> mEvents = new MutableLiveData<>();
        
    public LiveData<List<Event>> getEvents() {
        return mEvents;
    }

    @Override
    public void attachView(MyMvpContract.View view) {        
        if (mView == null) { 
            mView = view;
            getEvents().observe((LifecycleOwner) view, events -> {
                 //call View method to update UI
            });
        }
        // do nothing if fragment was not distroyed but only was hidden
    }

    @Override
    public void detachView() {
        mView = null;
    }

    //Some other code
}

MyView.java

public class MyView extends LifecycleFragment implements MyMvpContract.View {
    private MyMvpContract.Presenter mPresenter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mPresenter = ViewModelProviders.of(this).get(SimInfoPresenter.class);       
        // some code
        mPresenter.attachView(this);
        return v;
    }

    @Override
    public void onDestroy() {
        mPresenter.detachView();
        super.onDestroy();
    }
    
    //some other code
}