No puedo entender por qué obtengo una vista de lista nula al intentar mi url con cartero. Creo que mi parte de Android tiene algún problema, pero no tengo idea de dónde está el problema.

Ver actividad de pedido

public class ViewOrderActivity extends AppCompatActivity {

private ListView listView3;

private CustomAdapter2 listAdapter2;
ArrayList<Order> orderlist = new ArrayList<>();


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_order);
    User user = SharedPrefManager.getInstance(this).getUser();
    String str_oid=String.valueOf(user.getId());
    String type="cancel";
    BackgroundWorker backgroundWorker=new BackgroundWorker(this);
    backgroundWorker.execute(type,str_oid);
    listView3 = (ListView) findViewById(R.id.listView3);
    getJSON("http://192.168.28.1/restaurant/getorder.php");

}


private void getJSON(final String urlWebService) {

    class GetJSON extends AsyncTask<Void, Void, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }


        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);

            try {
                loadIntoListView(s);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

        @Override
        protected String doInBackground(Void... voids) {
            try {
                URL url = new URL(urlWebService);
                HttpURLConnection con = (HttpURLConnection) url.openConnection();
                StringBuilder sb = new StringBuilder();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
                String json;
                while ((json = bufferedReader.readLine()) != null) {
                    sb.append(json + "\n");
                }
                return sb.toString().trim();
            } catch (Exception e) {
                return null;
            }
        }
    }
    GetJSON getJSON = new GetJSON();
    getJSON.execute();
}

private void loadIntoListView(String json) throws JSONException {
    JSONArray jsonArray = new JSONArray(json);

    for (int i = 0; i < jsonArray.length(); i++) {
        JSONObject obj = jsonArray.getJSONObject(i);
        orderlist.add(new Order(obj.getInt("orderid"), obj.getInt("pickuptime"), obj.getInt("pickupdate")));
    }
    listAdapter2 = new CustomAdapter2(this, orderlist);
    listView3.setAdapter(listAdapter2);

  }
}

Este es un adaptador personalizado donde se estructura la vista de lista.

Adaptador personalizado

class CustomAdapter2 extends BaseAdapter {
public ArrayList<Order> ordlists;
private Context context;
CustomAdapter2(Context context, ArrayList<Order> ordlists) {
    //super(context, R.layout.item_food, strilist);
    this.context = context;
    this.ordlists = ordlists;
}
@Override
public int getCount(){

    return ordlists.size();
}
@Override
public Order getItem(int position){
    return ordlists.get(position);
}
@Override
public long getItemId(int position){
    return 0;
}

@NonNull
@Override
public View getView(final int position, View convertView, @NonNull ViewGroup parent) {
    final ListViewHolder2 listViewHolder2;
    View customView2;
    if(convertView == null)
    {
        LayoutInflater menuInflater2 = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        // LayoutInflater menuInflater = LayoutInflater.from(getContext());
        customView2 = menuInflater2.inflate(R.layout.item_order, parent, false);
        listViewHolder2 = new ListViewHolder2();
        listViewHolder2.tvorderid = (TextView) customView2.findViewById(R.id.tvorderid );
        listViewHolder2.tvtime = (TextView) customView2.findViewById(R.id.tvtime);
        listViewHolder2.tvdate = (TextView) customView2.findViewById(R.id.tvdate);
        listViewHolder2.btncancel = (Button) customView2.findViewById(R.id.btncancel);

        customView2.setTag(listViewHolder2);
    }
    else
    {
        customView2=convertView;
        listViewHolder2= (ListViewHolder2) customView2.getTag();
    }

    final Order order=getItem(position);
    //Typeface customfont= Typeface.createFromAsset(parent.getContext().getAssets(),"fonts");
    listViewHolder2.tvorderid.setText(String.valueOf(order.getOrderid()));
    listViewHolder2.tvorderid.setTextColor(Color.YELLOW);
    listViewHolder2.tvorderid.setTextSize(10);
    listViewHolder2.tvtime.setText(String.valueOf(order.getPickuptime()));
    listViewHolder2.tvtime.setTextColor(Color.YELLOW);
    listViewHolder2.tvtime.setTextSize(10);
    listViewHolder2.tvdate.setText(String.valueOf(order.getPickupdate()));
    listViewHolder2.tvdate.setTextColor(Color.YELLOW);
    listViewHolder2.tvdate.setTextSize(10);

    listViewHolder2.btncancel.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {


        }
    });

    return customView2;
}

Trabajador de fondo para cancelar tipo

else if (type.equals("cancel")){
        try{
            String id=params[1];
            URL url=new URL(cancel_url);
            HttpURLConnection httpURLConnection=(HttpURLConnection)url.openConnection();
            httpURLConnection.setRequestMethod("POST");
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            OutputStream outputStream=httpURLConnection.getOutputStream();
            BufferedWriter bufferedWriter=new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
            String post_data= URLEncoder.encode("id","UTF-8")+"="+URLEncoder.encode(id,"UTF-8");
            bufferedWriter.write(post_data);
            bufferedWriter.flush();
            bufferedWriter.close();
            outputStream.close();
            InputStream inputStream=httpURLConnection.getInputStream();
            BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
            String result="";
            String line="";
            while((line=bufferedReader.readLine())!=null){
                result+=line;
            }
            bufferedReader.close();
            inputStream.close();
            httpURLConnection.disconnect();
            return result;
        }catch(MalformedURLException e){
            e.printStackTrace();
        }catch (IOException e){
            e.printStackTrace();
        }
    }

Este es mi código para url getorder.php

<?php

$hostname = "localhost";
$username = "root";
$password = "";
$database = "y77";

$conn = new mysqli($hostname, $username, $password, $database);


if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

$orders = array(); 
session_start();


$id=$_POST["id"];
$stmt =$conn->prepare("SELECT `orderid`, `pickuptime`, `pickupdate` FROM `order` WHERE `id`=$id");

$stmt->execute();

$stmt->bind_result($orderid, $pickuptime, $pickupdate);

while($stmt->fetch()){
$temp = [
'orderid'=>$orderid,
'pickuptime'=>$pickuptime,
'pickupdate'=>$pickupdate
];
array_push($orders, $temp);
}

echo json_encode($orders);
?>