RecyclerView.ViewHolderからDialogFragmentを呼び出す方法（インターフェース実装を使用）

このような状況についての関連する質問はほとんど見られませんでしたが、解決策が見つからなかったため、私の問題は次のようになります。

私は4つのフラグメントを保持するtabLayoutを持っています、フラグメント番号3（カタログ）でユーザーにデータを配信しています、このフラグメントはcardViewのrecyclerViewを保持し、dialogFragmentを呼び出すカードのonclicklistnerを実装しようとしています、私はそうするための最も効率的な方法を理解しています、 viewHolderのインターフェイスを使用すると、recyclerViewアダプターコンストラクターで1つの問題に直面します。

カタログフラグメントは次のとおりです。

public class CatalogFragment extends Fragment implements CustomAdapter.OnItemClickListener {

private FloatingActionButton mSharedFab;
private List<MyProducts> productsList;

//Creating Views
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;

private CustomAdapter.OnItemClickListener listener;//////LISTNER FOR DIALOG???

//Volley Request 
private RequestQueue requestQueue;

//request counter 
private int requestCount = 1;
private static final String URL_INDEX = "http://myserverip/product.php";
//Tag values to read from json
public static final String TAG_IMAGE_URL = "product_img";
public static final String TAG_PRODUCT_SN = "product_serial_num";
public static final String TAG_PRODUCT_TITLE = "product_title";
public static final String TAG_PRODUCT_PRICE = "product_price";
public static final String TAG_PRODUCT_DESCRIPTION = "product_description";

public CatalogFragment() {
    // Required empty public constructor
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_catalog, container, false);
    recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
    layoutManager = new LinearLayoutManager(getActivity().getApplicationContext(), LinearLayoutManager.VERTICAL, false);
    recyclerView.setLayoutManager(layoutManager);
    //recyclerView.setHasFixedSize(true);
    RecyclerView.ItemAnimator itemAnimator = new DefaultItemAnimator();
    itemAnimator.setAddDuration(1000);
    itemAnimator.setRemoveDuration(1000);
    recyclerView.setItemAnimator(itemAnimator);

    //Initializing our product list
    productsList = new ArrayList<>();
    requestQueue = Volley.newRequestQueue(getActivity().getApplicationContext());

    // fetch data
    getData();



    //initialize adapter

    adapter = new CustomAdapter(listener, productsList, getActivity());
    //Adding adapter to recyclerview
    recyclerView.setAdapter(adapter);
    return view ;
}
 @Override
public void onItemClicked(View v) {
    DialogAddToCartFragment df= new DialogAddToCartFragment();
    df.show(getFragmentManager(), "Dialog");
}

アダプターは、customadapterを使用して3つのパラメーターでインスタンス化されました。

customAdapterクラス：

public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {

public interface OnItemClickListener {
    void onItemClicked(View v);
}

private OnItemClickListener listener;
//Image loader inst for image
private ImageLoader imageLoader;

private Context context;
public Snackbar snackbar;
String title;
//List  all products
List<MyProducts> myProducts;

public CustomAdapter( OnItemClickListener listener, List<MyProducts> myProducts, Context context)
{
    super();
    this.listener = listener;
    this.myProducts = myProducts;
    this.context = context;
}

@Override
public CustomAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.product_list, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
}

@Override
public void onBindViewHolder(CustomAdapter.ViewHolder holder, int position) {

    if( myProducts != null) {
        MyProducts myProducts1 = myProducts.get(position);
        imageLoader = ImageVolley.getInstance(context).getImageLoader();
        imageLoader.get(myProducts1.getProductImage(), ImageLoader.getImageListener(holder.imageView, R.drawable.android_store_log, android.R.drawable.ic_dialog_alert));
        title = myProducts1.getProductTitle();
        //Showing data to the views
        holder.imageView.setImageUrl(myProducts1.getProductImage(), imageLoader);
        holder.textViewProductTitle.setText(myProducts1.getProductTitle());
        holder.textViewProductDescription.setText(myProducts1.getProductDescription());
        holder.textViewProductSerialNumber.setText(myProducts1.getProductSn());
        holder.textViewProductPrice.setText(myProducts1.getProductPrice());
    }
}

@Override
public int getItemCount() {
    return myProducts.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
    //Views
    public NetworkImageView imageView;
    public TextView textViewProductTitle;
    public TextView textViewProductDescription;
    public TextView textViewProductSerialNumber;
    public TextView textViewProductPrice;

    //Initializing Views
    public ViewHolder(final View itemView) {
        super(itemView);
        imageView = (NetworkImageView) itemView.findViewById(R.id.imageViewProduct);
        textViewProductTitle = (TextView) itemView.findViewById(R.id.textViewProductTitle);
        textViewProductDescription = (TextView) itemView.findViewById(R.id.textViewProductDescription);
        textViewProductSerialNumber = (TextView) itemView.findViewById(R.id.textViewProductSerialNumber);
        textViewProductPrice = (TextView) itemView.findViewById(R.id.textViewProductPrice);

        itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                listener.onItemClicked(v);/////////DIALOG LISTENER????
            }
        });
    }
}

DialogFragment：

public class DialogAddToCartFragment extends DialogFragment {



@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
    View view = getActivity().getLayoutInflater().inflate(R.layout.fragment_dialog_add_to_cart, new LinearLayout(getActivity()), false);

    // Retrieve layout elements
    //TextView title = (TextView) view.findViewById(R.id.text_title);

    // Set values
    //title.setText("Not perfect yet");

    // Build dialog
    Dialog builder = new Dialog(getActivity());
    builder.requestWindowFeature(Window.FEATURE_NO_TITLE);
    builder.getWindow().setBackgroundDrawable(new ColorDrawable(Color.GREEN));
    builder.setContentView(view);
    return builder;

}

}

カードをクリックすると、プログラムが閉じます:(

ログは次のとおりです。

07-12 08:42:22.685 2808-2808/com.example.get2i.androidstore E/AndroidRuntime: FATAL EXCEPTION: main
                                                                          Process: com.example.get2i.androidstore, PID: 2808
                                                                          java.lang.NullPointerException: Attempt to invoke interface method 'void com.example.get2i.androidstore.CustomAdapter$OnItemClickListener.onItemClicked(android.view.View)' on a null object reference
                                                                              at com.example.get2i.androidstore.CustomAdapter$ViewHolder$1.onClick(CustomAdapter.java:102)
                                                                              at android.view.View.performClick(View.java:5198)
                                                                              at android.view.View$PerformClick.run(View.java:21147)
                                                                              at android.os.Handler.handleCallback(Handler.java:739)
                                                                              at android.os.Handler.dispatchMessage(Handler.java:95)
                                                                              at android.os.Looper.loop(Looper.java:148)
                                                                              at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                              at java.lang.reflect.Method.invoke(Native Method)
                                                                              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

catalogfragでCustomAdapter.OnItemClickListenerリスナーをどのようにインスタンス化する必要がありますか？アドバイスはありますので、よろしくお願いします！