[Help] Android - Convert JSON object for ArrayAdapter and ListView object

HttpClientFactory.java

public class HttpClientFactory {

    private HttpClient client;
    private HttpPost httpPost;
    private HttpGet httpGet;
    private String responseBody;

    public JSONObject sendGet(String url) {
        client = new DefaultHttpClient();
        httpGet = new HttpGet(Extras.BASE_URL + Extras.BASE_API + url);

        try {
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            responseBody = client.execute(httpGet, responseHandler);

            if (isJson(responseBody)) {
                return new JSONObject(responseBody);
            }
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    private boolean isJson(String str) {
        try {
            new JSONObject(str);
        } catch (JSONException e) {
            try {
                new JSONArray(str);
            } catch (JSONException e1) {
                return false;
            }
        }
        return true;
    }
}

JSON_data.json

{
    "content": [
        {
            "id": 1,
            "title": "Item 1",
            "children": []
        },
        {
            "id": 2,
            "title": "Item 2",
            "children": []
        },
        {
            "id": 3,
            "title": "Item 3",
            "children": []
        },
    ],
    "api_version": 1
}

Product.java

public class Product {
    int id;
    String title;
    ArrayList children;

    public Product(JSONObject object) {
        try {
            this.id = object.getInt("id");
            this.title = object.getString("title");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    public static ArrayList<Product> fromJson(JSONArray jsonObjects) {
        ArrayList<Product> products = new ArrayList<Product>();
        for (int i = 0; i < jsonObjects.length(); i++) {
            try {
                products.add(new Product(jsonObjects.getJSONObject(i)));
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
        return products;
    }

    public ArrayList getChildren() {
        return children;
    }

    public void setChildren(ArrayList children) {
        this.children = children;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    @Override
    public String toString() {
        return id + " - " + title;
    }
}

ProductAdapter.java

public class ProductAdapter extends ArrayAdapter<Product> {
    private List<Product> productList;
    private Context context;

    public ProductAdapter(List<Product> productList, Context ctx) {
        super(ctx, R.layout.row_layout, productList);

        this.productList = productList;
        this.context = ctx;
    }

    public int getCount() {
        if (productList != null)
            return productList.size();
        return 0;
    }

    public Product getItem(int position) {
        if (productList != null)
            return productList.get(position);
        return null;
    }

    public long getItemId(int position) {
        if (productList != null)
            return productList.get(position).hashCode();
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            // row_layout.xml file for list items
            convertView = inflater.inflate(R.layout.row_layout, parent, false);
        }

        Product product = productList.get(position);

        TextView textId = (TextView) convertView.findViewById(R.id.id);
        textId.setText(product.getId());

        TextView textTitle = (TextView) convertView.findViewById(R.id.title);
        textTitle.setText(product.getTitle());

        return convertView;
    }
}

res__layout__custom_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_main"
    tools:context=".MainActivity"
    android:orientation="vertical"
    >

    <ListView
        android:id="@+id/custom_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        ></ListView>

</LinearLayout>

res__layout__row_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <TextView
        android:id="@+id/id"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:textStyle="bold"
        />

    <TextView
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:textSize="8dp"
        android:textStyle="italic"
        />

</LinearLayout>

StudentsListActivity.java

/**
 * MainActivity class
 */
public class StudentsListActivity extends AppCompatActivity {

    private ListView list;
    private TextView mTextView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

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

        mTextView = (TextView) findViewById(R.id.text);
        list = (ListView) findViewById(R.id.custom_list);
    }

    @Override
    protected void onResume() {
        super.onResume();

        AsyncTask<Void, Void, String> asyncTask = new TaskWS(StudentsListActivity.this).execute();
        try {
            Gson gson = new Gson();
            ProductList product = gson.fromJson(asyncTask.get(), ProductList.class);

//            ArrayAdapter<Product> adapter = new ArrayAdapter<Product>(StudentsListActivity.this, android.R.layout.simple_list_item_1, product.getContent());

            productAdapter = new ProductAdapter(product.getContent(), StudentsListActivity.this);
            list.setAdapter(productAdapter);
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }
    
    ...
}

TaskWS.java

public class TaskWS extends AsyncTask<Void, Void, JSONObject> {
    Activity mActivity;

    public TaskWS(Activity activity) {
        super();

        this.mActivity = activity;
    }

    @Override
    protected JSONObject doInBackground(Void... params) {
        return readProducts();
    }

    private JSONObject readProducts() {
        HttpClientFactory factory = new HttpClientFactory();
        JSONObject result = factory.sendGet(Extras.BASE_PRODUCTS);
        
        return result;
    }
}