viewholder onclickListener null object reference - adapter

Question

Attempt to invoke interface method 'void com.example.imovie.adapter.MovieItemClickListener.onMovieClick(com.example.imovie.models.Movie, android.widget.ImageView)' on a null object reference
public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.MyViewHolder> {
Context context ;
List<Movie> mData;
MovieItemClickListener movieItemClickListener;
public MovieAdapter(Context context, List<Movie> mData, MovieItemClickListener listener) {
this.context = context;
this.mData = mData;
movieItemClickListener = listener;
}
#NonNull
#Override
public MyViewHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(context).inflate(R.layout.item_movie,viewGroup,false);
return new MyViewHolder(view);
}
#Override
public void onBindViewHolder(#NonNull MyViewHolder myViewHolder, int i) {
myViewHolder.TvTitle.setText(mData.get(i).getTitle());
myViewHolder.ImgMovie.setImageResource(mData.get(i).getThumbnail());
}
#Override
public int getItemCount() {
return mData.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private TextView TvTitle;
private ImageView ImgMovie;
public MyViewHolder(#NonNull View itemView) {
super(itemView);
TvTitle = itemView.findViewById(R.id.item_movie_title);
ImgMovie = itemView.findViewById(R.id.item_movie_img);
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
movieItemClickListener.onMovieClick(mData.get(getAdapterPosition()),ImgMovie);//i have a null object reference
}
});
}
}
}
public class HomeFragment extends Fragment implements MovieItemClickListener {
private HomeViewModel homeViewModel;
private List<Slide> listSlides;
private ViewPager slidePager;
private TabLayout indicator;
private RecyclerView moviesRV;
private RecyclerView moviesRV2;
private MovieItemClickListener movieItemClickListener;
public View onCreateView(#NonNull LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
homeViewModel =
ViewModelProviders.of(this).get(HomeViewModel.class);
View root = inflater.inflate(R.layout.fragment_home, container, false);
slidePager = root.findViewById(R.id.slider_pager);
indicator = root.findViewById(R.id.indicator);
moviesRV = root.findViewById(R.id.rsViewMovies);
moviesRV2 = root.findViewById(R.id.rsViewMovies2);
iniSlider();
final SliderPagerAdapter sliderPagerAdapteradapter = new SliderPagerAdapter(getContext(), listSlides);
final MovieAdapter movieAdapter = new MovieAdapter(getContext(), DateSource.getPopularMovies(), movieItemClickListener);
final Timer timer = new Timer();
timer.scheduleAtFixedRate(new SliderTimer(), 4000, 6000);
homeViewModel.getText().observe(this, new Observer<String>() {
#Override
public void onChanged(#Nullable String s) {
slidePager.setAdapter(sliderPagerAdapteradapter);
indicator.setupWithViewPager(slidePager, true);
moviesRV.setAdapter(movieAdapter);
moviesRV.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false));
moviesRV2.setAdapter(movieAdapter);
moviesRV2.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.HORIZONTAL, false));
}
});
return root;
}
#Override
public void onMovieClick(Movie movie, ImageView imageView) {
Intent intent = new Intent(getContext(), MovieDetailActivity.class);
intent.putExtra("title", movie.getTitle());
intent.putExtra("imgURL", movie.getThumbnail());
intent.putExtra("imgCover", movie.getCoverPhoto());
ActivityOptions options = ActivityOptions.makeSceneTransitionAnimation(getActivity(),
imageView, "sharedName");
startActivity(intent, options.toBundle());
Toast.makeText(getContext(), "item clicked : " + movie.getTitle(), Toast.LENGTH_LONG).show();
}
class SliderTimer extends TimerTask {
#Override
public void run() {
if (getActivity() != null) {
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
if (slidePager.getCurrentItem() < listSlides.size() - 1) {
slidePager.setCurrentItem(slidePager.getCurrentItem() + 1);
} else {
slidePager.setCurrentItem(0);
}
}
});
}
}
}
private void iniSlider() {
listSlides = new ArrayList<>();
listSlides.add(new Slide(R.drawable.a, "slide title \n movie title"));
listSlides.add(new Slide(R.drawable.b, "slide title"));
listSlides.add(new Slide(R.drawable.a, "slide title \n movie title"));
listSlides.add(new Slide(R.drawable.b, "slide title"));
}
}

Answer 1

If I'm not wrong, HomeFragment.movieItemClickListener is never initialized.
You may want to make the following changes in HomeFragment:
1. Delete the line
private MovieItemClickListener movieItemClickListener;
2. In this line
final MovieAdapter movieAdapter = new MovieAdapter(getContext(), DateSource.getPopularMovies(), movieItemClickListener);
change movieItemClickListener to this, because HomeFragment implements MovieItemClickListener.
That should fix the NullPointerException.