Null-Pointer-Exception in Recycler-Element erhalten Klick-Listener-Schnittstelle

Question

Ich weiß, diese Frage ist sehr, aber ich bin viel gesucht und ich bin nicht in der Lage, das Problem zu verstehen. Ich bin eine Schnittstelle für den Umgang mit Klick Hörer auf bestimmten Punkt Recycler Ansicht erstellen

Hier sind meine Klassen

MovieAdapter.java

package com.example.vikas.movie.adapter; 

/** 
* Created by vikas on 23/4/17. 
*/ 
import android.content.Context; 
import android.support.v7.widget.RecyclerView; 
import android.text.TextUtils; 
import android.util.Log; 
import android.view.HapticFeedbackConstants; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.ViewGroup; 
import android.widget.ImageView; 
import android.widget.RelativeLayout; 
import android.widget.TextView; 

import com.bumptech.glide.Glide; 
import com.bumptech.glide.load.engine.DiskCacheStrategy; 
import com.example.vikas.movie.R; 
import com.example.vikas.movie.helper.CircleTransformation; 
import com.example.vikas.movie.model.Movie; 

import java.util.List; 
public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.MovieViewHolder> 
{ 
    private static final String TAG=MovieAdapter.class.getSimpleName(); 

    private List<Movie> movies; 
    private int rowLayout; 
    private Context context; 
    private MovieAdapterListener listener; 


    public static class MovieViewHolder extends RecyclerView.ViewHolder 
    { 
     RelativeLayout moviesLayout; 
     TextView movieTitle; 
     TextView data; 
     TextView movieDescription; 
     TextView rating; 
     ImageView imageView; 


     public MovieViewHolder(View v) 
     { 
      super(v); 
      moviesLayout = (RelativeLayout) v.findViewById(R.id.movie_layout); 
      movieTitle = (TextView) v.findViewById(R.id.title); 
      data = (TextView) v.findViewById(R.id.subtitle); 
      movieDescription = (TextView) v.findViewById(R.id.description); 
      rating = (TextView) v.findViewById(R.id.rating); 
      imageView=(ImageView)v.findViewById(R.id.movie_image); 
     } 



    } 

    public MovieAdapter(List<Movie> movies, int rowLayout, Context context) 
    { 
     this.movies = movies; 
     this.rowLayout = rowLayout; 
     this.context = context; 
    } 

    @Override 
    public MovieAdapter.MovieViewHolder onCreateViewHolder(ViewGroup parent, 
                  int viewType) 
    { 
     View view = LayoutInflater.from(parent.getContext()).inflate(rowLayout, parent, false); 
     return new MovieViewHolder(view); 
    } 


    @Override 
    public void onBindViewHolder(MovieViewHolder holder, final int position) 
    { 
     Movie movie= movies.get(position); 
     holder.movieTitle.setText(movies.get(position).getTitle()); 
     holder.data.setText(movies.get(position).getReleaseDate()); 
     holder.movieDescription.setText(movies.get(position).getOverview()); 
     holder.rating.setText(movies.get(position).getvote_average().toString()); 
     MovieImage(holder,movie); 
     applyClickEvents(holder,position); 


    } 
    private void applyClickEvents(MovieViewHolder holder,final int position) 
    { 
     holder.moviesLayout.setOnClickListener(new View.OnClickListener() 
     { 
      @Override 
      public void onClick(View view) 
      { 
       listener.onItemClicked(position); 
      } 
     }); 


    } 


    private void MovieImage(MovieViewHolder holder,Movie movie) 
    { 
     String base_URL="https://image.tmdb.org/t/p/"; 
     String size_Image="w500"; 
     String file_Path=movie.getPosterPath(); 

     StringBuilder image_Path=new StringBuilder(); 
     image_Path.append(base_URL).append(size_Image).append(file_Path); 
     Log.d(TAG,"movie genere ids "+movie.getGenreIds()); 
     Log.d(TAG,"movie relese date "+movie.getReleaseDate()); 




     if(!TextUtils.isEmpty(image_Path)) 
     { 
      Glide.with(context).load(image_Path.toString()) 
        .thumbnail(0.5f) 
        .crossFade() 
        .transform(new CircleTransformation(context)) 
        .diskCacheStrategy(DiskCacheStrategy.ALL) 
        .into(holder.imageView); 
     } 
     else 
     { 
      holder.imageView.setImageResource(R.drawable.circle); 
     } 

    } 

    public interface MovieAdapterListener 
    { 
     void onItemClicked(int position); 

    } 


    @Override 
    public int getItemCount() 
    { 
     return movies.size(); 
    } 
} 

MainActivity.java in dem ich implenting die Schnittstelle und die zwingende Methode, die ich in der Schnittstelle deklariert habe.

package com.example.vikas.movie.activity; 

import android.support.design.widget.CoordinatorLayout; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.DefaultItemAnimator; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.util.Log; 
import android.widget.Toast; 


import com.example.vikas.movie.R; 
import com.example.vikas.movie.adapter.MovieAdapter; 
import com.example.vikas.movie.model.Movie; 
import com.example.vikas.movie.model.MoviesResponse; 
import com.example.vikas.movie.rest.ApiClient; 
import com.example.vikas.movie.rest.ApiInterface; 

import java.util.ArrayList; 
import java.util.List; 

import retrofit2.Call; 
import retrofit2.Callback; 
import retrofit2.Response; 

public class MainActivity extends AppCompatActivity implements MovieAdapter.MovieAdapterListener 
{ 

    private static final String TAG=MainActivity.class.getSimpleName(); 
    //get which got from web API 
    private final static String API_KEY="xxxxx"; 
    private CoordinatorLayout coordinatorLayout; 
    // private MovieAdapter movieAdapter; 
    private RecyclerView recyclerView; 
    private List<Movie> movieList = new ArrayList<>(); 

    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     coordinatorLayout=(CoordinatorLayout)findViewById(R.id.coordinate_layout); 

     if(API_KEY.isEmpty()) 
     { 
      Snackbar snackbar = Snackbar 
        .make(coordinatorLayout, "Please Enter The key", Snackbar.LENGTH_LONG); 

      snackbar.show(); 
      return; 
     } 
     recyclerView = (RecyclerView) findViewById(R.id.recycler_view); 
     recyclerView.setLayoutManager(new LinearLayoutManager(getApplicationContext())); 
     recyclerView.setItemAnimator(new DefaultItemAnimator()); 



     ApiInterface apiInterface= ApiClient.getClient().create(ApiInterface.class); 
     Call<MoviesResponse> call= apiInterface.getNowPlayingMovies(API_KEY); 
     call.enqueue(new Callback<MoviesResponse>() 
     { 
      @Override 
      public void onResponse(Call<MoviesResponse> call, Response<MoviesResponse> response) 
      { 

       movieList= response.body().getResults(); 
       Log.d(TAG, "Number of movies received: " + movieList.size()); 
       recyclerView.setAdapter(new MovieAdapter(movieList, R.layout.recyclerview_item_movie, getApplicationContext())); 
       // movieAdapter.notifyDataSetChanged(); 
       // Log.d(TAG, "Number of movies received: " + movieList.); 


      } 

      @Override 
      public void onFailure(Call<MoviesResponse> call, Throwable t) 
      { 
       Snackbar snackbar = Snackbar 
         .make(coordinatorLayout, "Please Check your Internet Connection", Snackbar.LENGTH_LONG); 

       snackbar.show(); 
       Log.e(TAG, t.toString()); 

      } 
     }); 

    } 

    @Override 
    public void onItemClicked(int position) 
    { 
     Movie movie = movieList.get(position); 
     movie.getGenreIds(); 
     movie.getId(); 
     Toast.makeText(getApplicationContext(), "id: "+ movie.getId(), Toast.LENGTH_SHORT).show(); 
    } 


} 

Ich erhalte logcat wie diese

FATAL EXCEPTION: main 
                     Process: com.example.vikas.movie, PID: 23565 
                     java.lang.NullPointerException: Attempt to invoke interface method 'void com.example.vikas.movie.adapter.MovieAdapter$MovieAdapterListener.onItemClicked(int)' on a null object reference 
                      at com.example.vikas.movie.adapter.MovieAdapter$1.onClick(MovieAdapter.java:97) 
                      at android.view.View.performClick(View.java:5205) 
                      at android.view.View$PerformClick.run(View.java:21164) 
                      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) 
04-26 23:56:00.538 23565-23565/com.example.vikas.movie I/Process: Sending signal. PID: 23565 SIG: 9 

jemand bitte helfen ich nicht in der Lage bin, das Problem zu verstehen.

Answer 1

Linie ändern Sie get NullPointerException ich n Ihrem Schnittstellen-Listener.

Ihre Schnittstelle Zuhörer in Ihrem Adapter Klasse initialisieren:

public MovieAdapter(List<Movie> movies, int rowLayout, Context context) { 
    this.movies = movies; 
    this.rowLayout = rowLayout; 
    this.context = context; 
    listener = (MovieAdapterListener) context; //add this 

} 

EDIT

Auch setzen nun den Adapter:

recyclerView.setAdapter(new MovieAdapter(movieList, R.layout.recyclerview_item_movie, MainActivity.this)); 

Answer 2

Dies geschieht, weil Sie nicht "Listener" initialisiert haben. Sie müssen den Listener übergeben, wenn Sie einen neuen MovieAdapter in MainActivity erstellen und ihn "Listener" zuweisen.

In MovieAdapter.java, ändern öffentliche MovieAdapter() in

public MovieAdapter(List<Movie> movies, int rowLayout, Context context, MovieAdapterListener listener) 
{ 
    this.movies = movies; 
    this.rowLayout = rowLayout; 
    this.context = context; 
    this.listener=listener; 
} 

und in MainActivity.java, die

recyclerView.setAdapter(new MovieAdapter(movieList, R.layout.recyclerview_item_movie, getApplicationContext())); 

in

recyclerView.setAdapter(new MovieAdapter(movieList, R.layout.recyclerview_item_movie, getApplicationContext(),listener)); 
//change "listener into the name of MovieAdapterListener object" 

Answer 3

ich die MovieAdapter glauben, dass die Zuhörer Mitglied initialisieren sollte :

public MovieAdapter(List<Movie> movies, int rowLayout, Context context, MovieAdapterListener lstn) 
{ 
    this.movies = movies; 
    this.rowLayout = rowLayout; 
    this.context = context; 
    this.listener = lstn; 
} 

Und in MainActivity sollten Sie eine andere Instanz es passieren, wenn Sie die Adapter sind einstellen, da es MovieAdapter.MovieAdapterListener Umsetzung:

recyclerView.setAdapter(new MovieAdapter(movieList, R.layout.recyclerview_item_movie, this, this));