Parse JSON data into Java Object Array-CodePudding

I am trying to gather json data and parse it into a java object, and then add it to an object array to later display into my list view & fragment. Here is my code:

import androidx.appcompat.app.AppCompatActivity;

import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;

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

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

public class MainActivity extends AppCompatActivity {
    ArrayList<Character> characterArray = new ArrayList<Character>();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        CharacterGetData characterGetData = new CharacterGetData();
        characterGetData.execute("https://swapi.dev/api/people/?format=json");
    }

//Character Class
class Character{
       String name;
       String height;
       String mass;

}

    class CharacterGetData extends AsyncTask<String, String, String> {
        String name;
        String height;
        String mass;


        @Override
        protected String doInBackground(String... args) {

            try {

                URL obj = new URL(args[0]);
                HttpURLConnection connection = (HttpURLConnection) obj.openConnection();
                connection.setRequestMethod("GET");


                BufferedReader in = new BufferedReader(
                        new InputStreamReader(connection.getInputStream()));
                String line;
                StringBuffer response = new StringBuffer();
                while ((line = in.readLine()) != null) {
                    response.append(line);

                }
                in.close();

                JSONObject jsonObj = new JSONObject(response.toString());
                Character character1 = new Character();
                character1.name = jsonObj.getString("name");
                character1.height = jsonObj.getString("height");
                character1.mass = jsonObj.getString("mass");
                characterArray.add(character1);


                Log.i("MainActivity", "The name is "   character1.name   "the height is "   character1.height);


            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException | JSONException e) {
                e.printStackTrace();
            }
            return null;
        }
    }}

The code runs properly, but when trying to confirm the results with the log message I am receiving the following in debugger:

W/System.err: org.json.JSONException: No value for name
W/System.err:     at org.json.JSONObject.get(JSONObject.java:400)
W/System.err:     at org.json.JSONObject.getString(JSONObject.java:561)
W/System.err:     at com.example.androidlabs.MainActivity$CharacterGetData.doInBackground(MainActivity.java:71)
W/System.err:     at com.example.androidlabs.MainActivity$CharacterGetData.doInBackground(MainActivity.java:43)
W/System.err:     at android.os.AsyncTask$3.call(AsyncTask.java:394)
W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:305)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
W/System.err:     at java.lang.Thread.run(Thread.java:923)

The JSON data( found at https://swapi.dev/api/people/?format=json) looks like :

{"count":82,"next":"https://swapi.dev/api/people/?page=2&format=json","previous":null,"results":[{"name":"Luke Skywalker","height":"172","mass":"77","hair_color":"blond","skin_color":"fair","eye_color":"blue","birth_year":"19BBY","gender":"male","homeworld":"https://swapi.dev/api/planets/1/","films":["https://swapi.dev/api/films/1/","https://swapi.dev/api/films/2/","https://swapi.dev/api/films/3/","https://swapi.dev/api/films/6/"],"species":[],"vehicles":["https://swapi.dev/api/vehicles/14/","https://swapi.dev/api/vehicles/30/"],"starships":["https://swapi.dev/api/starships/12/","https://swapi.dev/api/starships/22/"],"created":"2014-12-09T13:50:51.644000Z","edited":"2014-12-20T21:17:56.891000Z","url":"https://swapi.dev/api/people/1/"}

You can see that there is a name tag, so I am not sure why I am getting this error, nor how to fix this. I also tried using a JSONArray but also got an error. Any suggestions would be appreciated!

CodePudding user response：

You should get the result JSONArray from the response JSONObject and iterate through it like the following.

JSONObject jsonObj = new JSONObject(response.toString());
JSONArray jsonArray = jsonObj.getJSONArray("results");
for (int i = 0 ; i < jsonArray.length(); i  ) {
     JSONObject charecterObj = jsonArray.getJSONObject(i);
     Character character1 = new Character();
     character1.name = charecterObj.getString("name");
     character1.height = charecterObj.getString("height");
     character1.mass = charecterObj.getString("mass");
     characterArray.add(character1);
    }