MainActivity.java

package movies.anandsingh.net.movies;

import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
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.HashMap;
import java.util.Map;

public class MainActivity extends AppCompatActivity {
    TextView text;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Text to display response result
        text = (TextView) findViewById(R.id.textView);
        
        //Executing AsyncTask, passing api as parameter
        new CheckConnectionStatus().execute("https://api.themoviedb.org/3/movie/550?api_key=8476a7ab80ad76f0936744df0430e67c");
    }

    //AsyncTask to process network request
    class CheckConnectionStatus extends AsyncTask<String, Void, String> {
        //This method will run on UIThread and it will execute before doInBackground
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            
            //Making text field blank
            text.setText("");
        }

        //This method will run on background thread and after completion it will return result to onPostExecute
        @Override
        protected String doInBackground(String... params) {
            URL url = null;
            try {
                //As we are passing just one parameter to AsyncTask, so used param[0] to get value at 0th position that is URL
                url = new URL(params[0]);
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            try {
                HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

                //Getting inputstream from connection, that is response which we got from server
                InputStream inputStream = urlConnection.getInputStream();
                
                //Reading the response
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                String s = bufferedReader.readLine();
                bufferedReader.close();
                
                //Returning the response message to onPostExecute method
                return s;
            } catch (IOException e) {
                Log.e("Error: ", e.getMessage(), e);
            }
            return null;
        }

        //This method runs on UIThread and it will execute when doInBackground is completed
        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            
            JSONObject jsonObject = null;
            try {
                //Parent JSON Object. Json object start at { and end at }
                jsonObject = new JSONObject(s);

                //Array of parent JSON object
                Map<String, Integer> companiesMap = new HashMap<>();

                //JSON Array of parent JSON object. Json array starts from [ and end at ]
                JSONArray jsonArray = jsonObject.getJSONArray("production_companies");
                
                //Reading JSON object inside Json array
                for (int i =0; i<jsonArray.length();i++)
                {
                    //Reading JSON object at 'i'th position of JSON Array
                    JSONObject object = jsonArray.getJSONObject(i);
                    
                    //Setting the value to map
                    companiesMap.put(object.getString("name"), object.getInt("id"));

                }
                text.setText(String.valueOf(companiesMap.get("Linson Films")));

            } catch (JSONException e) {
                e.printStackTrace();
            }

        }
    }
}