Erro parsing JSON data

Mobile Android
#1

Estou a tentar desenvolver um programa em Android para a escola, mas não tenho experiência nenhuma.

Está-me a dar o erro de parsing JSON data.

Aqui está o código php:

<?php $con=mysqli_connect("localhost","prof","dbesms","prr"); if (mysqli_connect_errno($con)) { echo '{"query_result":"ERROR"}'; } $userName = $_GET['username']; $passWord = $_GET['password']; $result = mysqli_query($con,"SELECT * FROM login WHERE User='$userName' AND Pass='$passWord'"); $numRegistos=mysqli_num_rows($result); if($result == true && $numRegistos>0) { echo '{"query_result":"SUCCESS","numMesas":"6"}'; } else{ echo '{"query_result":"FAILURE"}'; } mysqli_close($con); ?>

Agora o código Android:

package com.example.toshiba.prr;

import android.content.Context;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

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

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;

public class Registo extends AsyncTask<String, Void, String> {
private Context context;

public Registo(Context context) {
    this.context = context;
}

protected void onPreExecute() {

}

@Override
protected String doInBackground(String... arg0) {
    String username = arg0[0];
    String password = arg0[1];


    String link;
    String data;
    BufferedReader bufferedReader;
    String result;

    try {
        data = "?username=" + URLEncoder.encode(username, "UTF-8");
        data += "&password=" + URLEncoder.encode(password, "UTF-8");

        link = "http://10.0.2.2/PRR/android/check.php"+data;
        URL url = new URL(link);
        HttpURLConnection con = (HttpURLConnection) url.openConnection();

        bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
        result = bufferedReader.readLine();
        return result;
    } catch (Exception e) {
        return new String("Exception: " + e.getMessage());
    }
}

@Override
protected void onPostExecute(String result) {
    Toast.makeText(context, "Resultado."+result, Toast.LENGTH_SHORT).show();
    String jsonStr = result;
    if (jsonStr != null) {
        try {
            JSONObject jsonObj = new JSONObject(jsonStr);
            String query_result = jsonObj.getString("query_result");
            if (query_result.equals("SUCCESS")) {
                String nMesas=jsonObj.getString("numMesas");
                Toast.makeText(context, "Data inserted successfully. Signup successful."+nMesas, Toast.LENGTH_SHORT).show();
                // chama proximo ecra enviando num Mesas.
                entraServico(nMesas);

            } else if (query_result.equals("FAILURE")) {
                Toast.makeText(context, "Data could not be inserted. Signup failed.", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(context, "Couldn't connect to remote database.", Toast.LENGTH_SHORT).show();
            }
        } catch (JSONException e) {
            e.printStackTrace();
            Toast.makeText(context, "Error parsing JSON data.", Toast.LENGTH_SHORT).show();
        }
    } else {
        Toast.makeText(context, "Couldn't get any JSON data.", Toast.LENGTH_SHORT).show();
    }
}
private void entraServico(String str) {
    Context esteContexto=this.context; // notar que context foi fefinido no topo da classe e portanto esta disponivel como variavel global;
    Intent i = new Intent(esteContexto,Tipo.class);

    Bundle bundle = new Bundle();
    bundle.putString("numMesa", str);
    i.putExtras(bundle);
    context.startActivity(i);
}

}

Agradecia desde já toda a ajuda.