App doesn't retrieve JSON data from PHP webservice. Webservice works fine
<p>My app doesn't seem to pull the JSON data from PHP webservice properly.</p>

<p>Visiting the webservice's function to get all data records from database produces JSON properly, but my app can't grab that data and seems to end up with <code>NullPointerException</code>.</p>

<p><strong>LogCat</strong> issues me this:</p>

<p><strong>Update:</strong></p>

<p>Noticed this error in yellow that happens before the below errors:</p>

<blockquote>
  <p>W/System.err(835): org.apache.http.conn.HttpHostConnectException:
  Connection to http:// localhost refused</p>
</blockquote>

<p>If I can't connect to the webservice on my localhost then I'm not getting the JSON to my app. But why would it refuse connection to localhost?</p>

<blockquote>
  <p>W/System.err(1159):   at
  com.example.myfirstapp.MainActivity$LoadAllCars.doInBackground(MainActivity.java:113)
  W/System.err(1159):   at
  com.example.myfirstapp.MainActivity$LoadAllCars.doInBackground(MainActivity.java:1)
  E/AndroidRuntime(1159):   at
  com.example.myfirstapp.MainActivity$LoadAllCars.doInBackground(MainActivity.java:116)
  E/AndroidRuntime(1159):   at
  com.example.myfirstapp.MainActivity$LoadAllCars.doInBackground(MainActivity.java:1)
  E/WindowManager(1159):    at
  com.example.myfirstapp.MainActivity$LoadAllCars.onPreExecute(MainActivity.java:103)</p>
</blockquote>

<p><em>Line 113:</em> <code>JSONObject json = jParser.makeHttpRequest(url_all_cars, "GET", params);</code>
<em>Line 116:</em> <code>Log.d("All Cars: ", json.toString());</code></p>

<p><strong>MainActivity</strong></p>

<pre><code>package com.example.myfirstproject;

//imports

public class MainActivity extends ListActivity implements OnItemClickListener {

    // Progress Dialog
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();

    ArrayList&lt;HashMap&lt;String, String&gt;&gt; carsList;

    // url to get all products list
    private static String url_all_cars = "http://localhost/webservice/get_all_cars.php";

    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_CARS = "cars";
    private static final String TAG_NAME = "name";

    // products JSONArray
    JSONArray cars = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Hashmap for ListView
        carsList = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;();

        // Loading products in Background Thread
        new LoadAllcars().execute();

        // Get listview
        ListView lv = getListView();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllcars extends AsyncTask&lt;String, String, String&gt; {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Loading cars. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting All products from url
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List&lt;NameValuePair&gt; params = new ArrayList&lt;NameValuePair&gt;();
            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url_all_cars, "GET", params);

            // Check your log cat for JSON reponse
            Log.d("All cars: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    cars = json.getJSONArray(TAG_CARS);

                    // looping through All Products
                    for (int i = 0; i &lt; cars.length(); i++) {
                        JSONObject c = cars.getJSONObject(i);

                        // Storing each json item in variable
                        String title = c.getString(TAG_NAME);

                        // creating new HashMap
                        HashMap&lt;String, String&gt; map = new HashMap&lt;String, String&gt;();

                        // adding each child node to HashMap key =&gt; value
                        map.put(TAG_NAME, name);

                        // adding HashList to ArrayList
                        carsList.add(map);
                    }
                } else {
                    // no products found
                    pDialog = new ProgressDialog(MainActivity.this);
                    pDialog.setMessage("No cars found");
                    pDialog.setIndeterminate(false);
                    pDialog.setCancelable(false);
                    pDialog.show();
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all products
            pDialog.dismiss();
            // updating UI from Background Thread
            runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            MainActivity.this, carsList,
                            android.R.id.list, new String[] {TAG_NAME},
                            new int[] { R.id.title });
                    // updating listview
                    setListAdapter(adapter);
                }
            });

        }
    }
}
</code></pre>

<p><strong>EDIT</strong></p>

<p><strong>JSONParser:</strong></p>

<pre><code>public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    // function get json from url
    // by making HTTP POST or GET mehtod
    public JSONObject makeHttpRequest(String url, String method,
            List&lt;NameValuePair&gt; params) {

        // Making HTTP request
        try {

            // check for request method
            if(method == "POST"){
                // request method is POST
                // defaultHttpClient
                DefaultHttpClient httpClient = new DefaultHttpClient();
                HttpPost httpPost = new HttpPost(url);
                httpPost.setEntity(new UrlEncodedFormEntity(params));

                HttpResponse httpResponse = httpClient.execute(httpPost);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();

            }else if(method == "GET"){
                // request method is GET
                DefaultHttpClient httpClient = new DefaultHttpClient();
                String paramString = URLEncodedUtils.format(params, "utf-8");
                url += "?" + paramString;
                HttpGet httpGet = new HttpGet(url);

                HttpResponse httpResponse = httpClient.execute(httpGet);
                HttpEntity httpEntity = httpResponse.getEntity();
                is = httpEntity.getContent();
            }           

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line + "\n");
            }
            is.close();
            json = sb.toString();
        } catch (Exception e) {
            Log.e("Buffer Error", "Error converting result " + e.toString());
        }

        // try parse the string to a JSON object
        try {
            jObj = new JSONObject(json);
        } catch (JSONException e) {
            Log.e("JSON Parser", "Error parsing data " + e.toString());
        }

        // return JSON String
        return jObj;

    }
}
</code></pre>
