Applikation für Android aufgehört zu arbeiten, während JSON

Question

Having Problem in Applikation für Android-Parsing - Leider Arbeiten gestoppt

FATAL AUSNAHME: Haupt Prozess: com.example.faizanamin.myapplication, PID: 12590 java.lang.NullPointerException: Versuch Schnittstelle Methode aufzurufen 'int java.util.List.size()' auf null Objektreferenz

package com.example.faizanamin.myapplication; 

import android.content.Context; 
import android.os.AsyncTask; 
import android.support.annotation.NonNull; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.support.v7.widget.MenuItemHoverListener; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.view.accessibility.CaptioningManager; 
import android.widget.ArrayAdapter; 
import android.widget.Button; 
import android.widget.ImageButton; 
import android.widget.ImageView; 
import android.widget.ListView; 
import android.widget.RatingBar; 
import android.widget.TextView; 

import com.example.faizanamin.myapplication.models.MovieModel; 

import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.MalformedURLException; 
import java.net.URL; 
import java.util.ArrayList; 
import java.util.List; 

public class MainActivity extends AppCompatActivity { 
    private TextView tvData; 
    private ListView lvMovies; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     lvMovies = (ListView)findViewById(R.id.lvMovies); 

     //new JSONTask().execute("http://android.devfever.com/moviesdemo.txt"); 


    } 

    public class JSONTask extends AsyncTask<String, String, List<MovieModel> >{ 
     @Override 
     protected List<MovieModel> doInBackground(String... params) { 
      HttpURLConnection connection = null; 
      BufferedReader reader = null; 
      try { 
       URL url=new URL(params[0]); 
       connection = (HttpURLConnection)url.openConnection(); 
       connection.connect(); 

       InputStream stream = connection.getInputStream(); 

       reader = new BufferedReader(new InputStreamReader(stream)); 
       String line=""; 
       StringBuffer buffer = new StringBuffer(); 
       while((line=reader.readLine())!=null){ 
        buffer.append(line); 
       } 

       String finalJson = buffer.toString(); 

       JSONObject parentObject = new JSONObject(finalJson); 
       JSONArray parentArray = parentObject.getJSONArray("movies"); 


       List<MovieModel> movieModelList = new ArrayList<>(); 
       for(int i=0;i<parentArray.length();i++) { 
        JSONObject finalObject = parentArray.getJSONObject(i); 
        MovieModel movieModel = new MovieModel(); 
        movieModel.setMovie(finalObject.getString("movie")); 
        movieModel.setYear(finalObject.getInt("year")); 
        movieModel.setRating((float) finalObject.getDouble("rating")); 
        movieModel.setDirector(finalObject.getString("director")); 
        movieModel.setDuration(finalObject.getString("duration")); 
        movieModel.setTagline(finalObject.getString("tagline")); 
        movieModel.setImage(finalObject.getString("image")); 
        movieModel.setStory(finalObject.getString("story")); 

        List<MovieModel.Cast> castList = new ArrayList<>(); 
        for(int j=0; j<finalObject.getJSONArray("cast").length(); j++){ 
         MovieModel.Cast cast = new MovieModel.Cast(); 
         cast.setName(finalObject.getJSONArray("cast").getJSONObject(j).getString("name")); 
         castList.add(cast); 
        } 
        movieModel.setCastList(castList); 
        movieModelList.add(movieModel); 
       } 
       return movieModelList; 
      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } finally { 
       if (connection!=null) { 
        connection.disconnect(); 
       } 
       try { 
        if(reader!=null){ 
         reader.close();} 
       } catch (IOException e) { 
        e.printStackTrace(); 
       } 
      } 
      return null; 
     } 

     @Override 
     protected void onPostExecute(List<MovieModel> result) { 
      super.onPostExecute(result); 

      // TODO NEED TO SET DATA 
      MovieAdapter adapter = new MovieAdapter(getApplicationContext(),R.layout.row,result); 
      lvMovies.setAdapter(adapter); 
     } 
    } 
    public class MovieAdapter extends ArrayAdapter{ 

     private List<MovieModel> movieModelList; 
     private int resource; 
     private LayoutInflater inflater; 
     public MovieAdapter(Context context, int resource, List<MovieModel> objects) { 
      super(context, resource, objects); 
      movieModelList = objects; 
      this.resource = resource; 
      inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE); 


     } 

     @Override 
     public View getView(int position, View convertView, ViewGroup parent) { 
      if(convertView == null){ 
       convertView = inflater.inflate(resource,null); 
      } 
      ImageView lvMovieIcon; 
      TextView tvMovie,tvTagline,tvYear,tvDuration,tvDirector,tvCast,tvStory; 
      RatingBar rMovieRating; 

      lvMovieIcon = (ImageView)findViewById(R.id.imageView); 
      tvMovie = (TextView)findViewById(R.id.movieName); 
      tvTagline = (TextView)findViewById(R.id.tagline); 
      tvYear = (TextView)findViewById(R.id.year); 
      tvDuration = (TextView)findViewById(R.id.duration); 
      tvDirector = (TextView)findViewById(R.id.director); 
      rMovieRating = (RatingBar) findViewById(R.id.rating); 
      tvCast = (TextView)findViewById(R.id.cast); 
      tvStory = (TextView)findViewById(R.id.story); 

      tvMovie.setText(movieModelList.get(position).getMovie()); 
      tvTagline.setText(movieModelList.get(position).getTagline()); 
      tvYear.setText("Year: "+movieModelList.get(position).getYear()); 
      tvDuration.setText(movieModelList.get(position).getDuration()); 
      tvDirector.setText(movieModelList.get(position).getDirector()); 
      //Rating Bar 
      rMovieRating.setRating(movieModelList.get(position).getRating()/2); 
      StringBuffer stringBuffer = new StringBuffer(); 
      for(MovieModel.Cast cast:movieModelList.get(position).getCastList()){ 
       stringBuffer.append(cast.getName()+", "); 
      } 
      tvCast.setText(stringBuffer); 
      tvStory.setText(movieModelList.get(position).getStory()); 
      return convertView; 
     } 
    } 
    @Override 
    public boolean onCreateOptionsMenu(Menu menu){ 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 
    @Override 
    public boolean onOptionsItemSelected(MenuItem item){ 
     int id = item.getItemId(); 
     if(id == R.id.action_refreash){ 
      new JSONTask().execute("http://android.devfever.com/allmovielist.txt"); 
      return true; 
     } 
     return super.onOptionsItemSelected(item); 
    } 
} 

Answer 1

Ich glaube, Sie sind nicht JSON von Ihrem Webservice immer so sollten Sie die Liste überprüfen in OnPostExecute und stellen Sie dann Adapter wie diese

 @Override 
     protected void onPostExecute(List<MovieModel> result) { 
      super.onPostExecute(result); 
      // TODO NEED TO SET DATA 
      if(result != null && result.size() > 0){ 
       MovieAdapter adapter = new MovieAdapter(getApplicationContext(),R.layout.row,result); 
       lvMovies.setAdapter(adapter); 
      } 
     }