How to receive an array from php to android using httpClient and JSON?

Question

I have the following code in php:

<?php 
try {
$gbd = new PDO('mysql:host=localhost;dbname=tramites', $username,$password);

$categoria = $_POST['categoria'];

$stmt = $gbd->prepare("SELECT nombre, categoria FROM tramite WHERE categoria = :categ");
$result = $stmt->execute(array("categ"=>$categoria));
    $i=0;
$arreglo = array(); // arreglo para enviar
$result2 = $stmt->fetchAll();
foreach ($result2 as $row)
{
    $arreglo[$i] = $row['nombre'].', '.$row['categoria'];
    $i++;
}

$gbd = null;
}
catch (PDOException $e)
{
    print "¡Error!: " . $e->getMessage() . "<br/>";
    die();
}

if($i >= 0)
{
    echo json_encode($arreglo);
}
?>

this code i´ts called from an android app and I need to receive the arreglo array in android but it returns null I don't know why.

My main code:

@Override
public boolean onOptionsItemSelected(MenuItem item)
{
    int id = item.getItemId();
    if (id == R.id.action_settings2) // JSON
    {
        String n="";
        HttpHandler handler= new HttpHandler();
        String txt=handler.getTramites2("tramites");
        n = parseProfilesJson(txt);
        Toast.makeText(this, "ca / "+ n+" /  "+ txt, Toast.LENGTH_LONG).show();
    }
    return super.onOptionsItemSelected(item);
}


public String parseProfilesJson(String the_json)
{
    String res="";
    try {
        JSONObject myjson = new JSONObject(the_json);

        JSONArray nameArray = myjson.names();
        JSONArray valArray = myjson.toJSONArray(nameArray);
        for(int i=0;i<valArray.length();i++)
        {
            String p = nameArray.getString(i) + "," + valArray.getString(i);
            res = res + p;
            //Toast.makeText(this, "ca "+ n, Toast.LENGTH_LONG).show();
        }
    } catch (JSONException e)
        { e.printStackTrace(); }
    return res;
}

and the class that is the HttpHandler:

public class HttpHandler
{
protected String url = "http://192.168.43.98/tramitapue/";
static String json = "";
public String getTramites2(String categoria)
{
    try{
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(url+"getTramites2.php");
        //Parámetros
        List<NameValuePair> params = new ArrayList<NameValuePair>();

        params.add(new BasicNameValuePair("categoria", categoria));

        // envio los parametros
        httppost.setEntity(new UrlEncodedFormEntity(params));

        HttpResponse resp = httpclient.execute(httppost);

        // recibo paramteros
        //HttpEntity ent = resp.getEntity();

        ////////////////////////////////////
        // here i put json content
        // trace response
        InputStream is = resp.getEntity().getContent();
        //convert response to string
        BufferedReader myReader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"));
        StringBuilder sb = new StringBuilder();
        sb.append(myReader.readLine() + "\n");
        String line="";
        while ((line = myReader.readLine()) != null) {
            sb.append(line + "\n");
        }
        json = sb.toString();
        ////////////////////////////////////

        //String text = EntityUtils.toString(ent);

        return json;
    }catch(Exception e){ return "Error en la Conexión " + e;}

}

I don't get any error but I get a null value. If I try in php only with a string it works but I want an array. What´s wrong. I apologize in advance cause my variables are a mix beetwen spanish and english.

Answer 1

You could use JSON to encode the results from your Query and parse them in your app.

Maybe this will help you: JSON Parser

Answer 2

You need to use Android - Json - PHP and PHP - Json - android.

Here a example