Android ListView using JSON Parsing with Volley

Question

I want to do a ListView that shows the user's orders. In the code below, I got "success" works but I can't get the order array to appear.

public void getOrderList() {
    SharedPreferences sharedPreferences = getSharedPreferences("UserData", Context.MODE_PRIVATE);
    final String hpno = sharedPreferences.getString("hpno", DEFAULT);
    final OrderAdapter orderAdapter = new OrderAdapter(this, R.layout.row_layout);
    orderIdListView.setAdapter(orderAdapter);

    Response.Listener<String> responseListener = new Response.Listener<String>() {

        @Override
        public void onResponse(String response) {
            try {
                JSONObject jsonResponse = new JSONObject(response);
                boolean success = jsonResponse.getBoolean("success");

                if (success) {
                    JSONArray orderList = new JSONArray(response);
                    for (int i = 0; i < orderList.length(); i++) {
                        HashMap<String, String> map = new HashMap<String, String>();
                        JSONObject object = orderList.getJSONObject(i);
                        map.put("order_id", "Order Number: " + object.getString("order_id"));
                        orderAdapter.add(map);
                    }
                } else {
                    AlertDialog.Builder builder = new AlertDialog.Builder(ViewOrderActivity.this);
                    builder.setMessage("Order(s) Failed to be retrieved")
                            .setNegativeButton("Retry", null)
                            .create()
                            .show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    };

    ViewOrderRequest viewOrderRequest = new ViewOrderRequest(hpno, responseListener);
    RequestQueue queue = Volley.newRequestQueue(ViewOrderActivity.this);
    queue.add(viewOrderRequest);
}

OrderAdapter:

public class OrderAdapter extends ArrayAdapter {
    List list = new ArrayList();
    public OrderAdapter(Context context, int resource) {
        super(context, resource);
    }

    public void add(Order order) {
        list.add(order);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
         return list.add(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row;
        row = convertView;
        OrderHolder orderHolder;
        if (row == null) {
            LayoutInflater layoutInflater = (LayoutInflater) this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = layoutInflater.inflate(R.layout.row_layout, parent, false);
            orderHolder = new OrderHolder();
            orderHolder.orderIdText = (TextView) row.findViewById(R.id.orderIdText);
            row.setTag(orderHolder);
        } else {
            orderHolder = (OrderHolder) row.getTag();
        }
        Order order = (Order) this.getItem(position);
        orderHolder.orderIdText.setText(order.getOrder_id());
        return row;
    }

    static class OrderHolder {
        TextView orderIdText;
    }
}

My PHP code:

<?php
    require "init.php";

    $hpno = $_POST['hpno'];

    $statement = mysqli_prepare($con, "SELECT * FROM `Order` WHERE hpno = ?") or die(mysqli_error($con));
    mysqli_stmt_bind_param($statement, "s", $hpno);
    mysqli_stmt_execute($statement);

    mysqli_stmt_store_result($statement);
    mysqli_stmt_bind_result($statement, $order_id, $total_price, $quantity, $payment_status, $hpno, $menu_id, $ordered_on);

    $response = array();
    $response["success"] = false;  

    while(mysqli_stmt_fetch($statement)){
        $response["success"] = true;
        array_push($response, array("order_id"=>$order_id, "total_price"=>$total_price, "quantity"=>$quantity));
    }

    echo json_encode($response);
?>

JSON Return:

{
    "success": true,
    "0": {
        "order_id": 21,
        "total_price": 6,
        "quantity": 1
    },
    "1": {
        "order_id": 22,
        "total_price": 18,
        "quantity": 3
    },
    "2": {
        "order_id": 23,
        "total_price": 25,
        "quantity": 5
    },
    "3": {
        "order_id": 24,
        "total_price": 35,
        "quantity": 5
    }
}

LOGCAT:

04-19 22:43:17.280 15452-15452/wqyap762.rprqs W/System.err: org.json.JSONException: Value {"success":true,"0":{"order_id":21,"total_price":6,"quantity":1},"1":{"order_id":22,"total_price":18,"quantity":3},"2":{"order_id":23,"total_price":25,"quantity":5},"3":{"order_id":24,"total_price":35,"quantity":5}} of type org.json.JSONObject cannot be converted to JSONArray

The error is from this line:

JSONArray orderList = new JSONArray(response);

I have been using many methods to retrieved from database, but all did not work.

Answer 1

Your JSON isn't correctly formatted. If you want your code to work as intented your JSON should be:

{
    "success": true,
    "values": [ {
        "order_id": 21,
        "total_price": 6,
        "quantity": 1
    },
    {
        "order_id": 22,
        "total_price": 18,
        "quantity": 3
    },
    {
        "order_id": 23,
        "total_price": 25,
        "quantity": 5
    },
    {
        "order_id": 24,
        "total_price": 35,
        "quantity": 5
    }]
}

And your code something like:

JSONArray orderList = new JSONArray(response.getJSONArray("values"));

Answer 2

For a start you need to notify your adapter's changes

if (success) {
       JSONArray orderList = new JSONArray(response);
       for (int i = 0; i < orderList.length(); i++) {
             HashMap<String, String> map = new HashMap<String, String>();
             JSONObject object = orderList.getJSONObject(i);
             map.put("order_id", "Order Number: " + object.getString("order_id"));
             orderAdapter.add(map);
        }
        oderAdapter.notifyDataSetChanged();
    }

Secondly, that error is pretty simple to understand, you are trying to parse a json as JSONArray that is of type JSONObject.

As @Benoit said, you should change your response when you fetch the data from the database, and get the values as array as he also wrote

Here is a question where it's explained how to parse your database results as json array

How to build a JSON array from mysql database