list view size error, says virtual method interface

Question

I created an app which shows data from json object from web to my movie list view. The error is that it says there is

 java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference.

Here is my full code that i have taken to load the movie parameters from web and display it as list.

MainActivity.java

package com.example.shailendra.jsonmovies;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

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;

import model.MovieModel;

public class MainActivity extends AppCompatActivity {
   ListView listView;

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

     //   new JsonTask().execute("http://jsonparsing.parseapp.com/jsonData/moviesDemoList.txt");



        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
    }


    public  class JsonTask extends AsyncTask<String,String,List<MovieModel>>
    { MovieAdapter adapter=null;
        @Override
        protected void onPostExecute(List<MovieModel> s) {
           try{
            super.onPostExecute(s);
            adapter= new MovieAdapter(getApplicationContext(),R.layout.row,s);
            listView.setAdapter(adapter);}
                    catch (Exception e)
            {
                e.printStackTrace();
            }




        }

        @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 is= connection.getInputStream();
                InputStreamReader isr= new InputStreamReader(is);
                reader= new BufferedReader(isr);
                StringBuffer buffer= new StringBuffer();

                String line=null;

                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<>();
                MovieModel movieModel= new MovieModel();
                  for(int i=0;i<parentArray.length();i++)
                {

                JSONObject finalObject= parentArray.getJSONObject(i);
                String movieName= finalObject.getString("movie");
                    movieModel.setMovie(finalObject.getString("movie"));
                     int year= finalObject.getInt("year");
                    movieModel.setYear(finalObject.getInt("year"));
                    movieModel.setRating((float)finalObject.getDouble("year"));
                    movieModel.setDirector(finalObject.getString("director"));
                    movieModel.setDuration(finalObject.getString("duration"));
                    movieModel.setTaglline(finalObject.getString("tagline"));
                    movieModel.setStory(finalObject.getString("story"));
                    movieModel.setImage(finalObject.getString("image"));

                    List<MovieModel.Cast> castList = new ArrayList<>();
                    for(int j=0;j<finalObject.getJSONArray("cast").length();j++)
                    {
                        JSONObject castObject= finalObject.getJSONArray("cast").getJSONObject(j);

                         MovieModel.Cast cast= new MovieModel.Cast();
                        cast.setName(castObject.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
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            new JsonTask().execute("http://jsonparsing.parseapp.com/jsonData/moviesDemoList.txt");
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

movieAdapter.java

package com.example.shailendra.jsonmovies;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.RatingBar;
import android.widget.TextView;

import java.util.List;

import model.MovieModel;

/**
 * Created by Shailendra on 10/21/2016.
 */
public class MovieAdapter extends ArrayAdapter{
   public List<MovieModel> movieModelList;
    int resource;
    LayoutInflater inflater;
    public MovieAdapter(Context context, int resource, List<MovieModel> objects) {
        super(context, resource, objects);
        movieModelList=objects;
        this.resource=resource;


    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        inflater=LayoutInflater.from(getContext());
        View customView=inflater.inflate(R.layout.row,parent,false);
        ImageView ivMovieIcon=(ImageView)customView.findViewById(R.id.ivIcon);
        TextView tvMovie=(TextView)customView.findViewById(R.id.tvMovie);
        TextView tvTagLine=(TextView)customView.findViewById(R.id.tvTagline);
        TextView tvYear=(TextView)customView.findViewById(R.id.tvYear);
        TextView tvDuration=(TextView)customView.findViewById(R.id.tvDuration);
        TextView tvDirector=(TextView)customView.findViewById(R.id.tvDirector);
        TextView tvCast=(TextView)customView.findViewById(R.id.tvCast);
        TextView tvStory=(TextView)customView.findViewById(R.id.tvStory);
        RatingBar ratingBare=(RatingBar) customView.findViewById(R.id.ratingBar);

        tvMovie.setText(movieModelList.get(position).getMovie());
        tvTagLine.setText(movieModelList.get(position).getTaglline());
        tvYear.setText("Year: "+movieModelList.get(position).getYear());
        tvDuration.setText(movieModelList.get(position).getDuration());
        tvDirector.setText(movieModelList.get(position).getDirector());
       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());
        ratingBare.setRating(movieModelList.get(position).getRating()/2);

        return customView;
    }
}

MovieModel.java

package model;

import java.util.List;

/**
 * Created by Shailendra on 10/21/2016.
 */
public class MovieModel {

    private String movie;
    private int year;
    private float rating;
    private String duration;
    private String director;
    private String taglline;
    private String image;
    private String story;
    private List<Cast> castList;

   public static class Cast {

     private String name;

       public String getName() {
           return name;
       }

       public void setName(String name) {
           this.name = name;
       }
   }


    public String getMovie() {
        return movie;
    }

    public void setMovie(String movie) {
        this.movie = movie;
    }

    public int getYear() {
        return year;
    }

    public void setYear(int year) {
        this.year = year;
    }

    public float getRating() {
        return rating;
    }

    public void setRating(float rating) {
        this.rating = rating;
    }

    public String getDuration() {
        return duration;
    }

    public void setDuration(String duration) {
        this.duration = duration;
    }

    public String getDirector() {
        return director;
    }

    public void setDirector(String director) {
        this.director = director;
    }

    public String getTaglline() {
        return taglline;
    }

    public void setTaglline(String taglline) {
        this.taglline = taglline;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

    public String getStory() {
        return story;
    }

    public void setStory(String story) {
        this.story = story;
    }

    public List<Cast> getCastList() {
        return castList;
    }

    public void setCastList(List<Cast> castList) {
        this.castList = castList;
    }
}

Possible duplicate of [Android app - Attempt to invoke interface method 'int java.util.List.size()' on a null object reference](http://stackoverflow.com/questions/31494891/android-app-attempt-to-invoke-interface-method-int-java-util-list-size-on) — Saeed Zhiany, Oct 22 '16 at 07:08

Harshad Pansuriya · Answer 1 · 2016-10-22T04:44:08.350

0

First of all define your MovieModel to global. and then Initialize it before you set adapter to your ListView. in your case you are not intialize your ArrayList.

do this way.

global declaration :

private ArrayList<MovieModel> movieModel;

and then inside your OnCreate method intialize it.

movie = new ArrayList<MovieModel>();

Example :

see this example :

http://androidexample.com/How_To_Create_A_Custom_Listview_-_Android_Example/index.php?view=article_discription&aid=67

edited Oct 22 '16 at 04:44

answered Oct 22 '16 at 04:06

Harshad Pansuriya

20,189
8
67
95

what is the meaning of movie? and where should i define movieModel.. can u please detail the answer? – rishav Oct 22 '16 at 04:37
@rishav i added simple example you will get the idea. – Harshad Pansuriya Oct 22 '16 at 04:44
bro can you please check my code and tell me... i am working for this since 2 days but i couldnot get any answer .. if you could do that , i am being crazy that any thing i try does not work – rishav Oct 22 '16 at 05:32

score 0 · Answer 2 · answered Oct 22 '16 at 04:09

0

In your adapter class override getCount() method

@Override
public int getCount() {
    if (movieModelList == null)
        return 0;
   movieModelList.size()
}

Also check what value is returned from AsyncTask's doInBackground().

answered Oct 22 '16 at 04:09

Sanjeet

2,385
1
13
22

when i do this app does not crash but nothing is shown – rishav Oct 22 '16 at 04:35
@rishav it means your movieModelList is not fill out. – dipali Oct 22 '16 at 04:49
@rishav Debug your code and check what's happening in Asynctask – Sanjeet Oct 22 '16 at 04:58
bro can you please check my code and tell me... i am working for this since 2 days but i couldnot get any answer .. if you could do that , i am being crazy that any thing i try does not work – rishav Oct 22 '16 at 05:32
@rishav Try to debug or put logs and check whether data is received from url or not. – Sanjeet Oct 22 '16 at 05:43

score 0 · Accepted Answer · answered Oct 22 '16 at 15:18

Check out the json link if it is correct and you can check the format if json is correct or not in www.jsonlint.com ---> point 1) Have to kept method getCount? put get Count and see what it returns

@Override
public int getCount() {
    if (movieModelList == null)
        return (0);
   movieModelList.size();
}

For array just define it globally --->point 2 After your app starts working you may get white text as if text is behind your current layout. For that use getBaseContext(); instead of getApplicationContext();

oh exactly what i wanted.. you saw my future problem of get context and answered it too . Thank you dude — rishav, Oct 22 '16 at 15:20

list view size error, says virtual method interface

3 Answers3