Cannot access database from Android application

I urgently and desperately need help.

I want to connect my Android application to a local database with

private static String loginURL = "localhost/android_login_api/";
private static String registerURL = "localhost/android_login_api/";

public JSONObject loginUser(String email, String password){
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("tag", login_tag));
        params.add(new BasicNameValuePair("email", email));
        params.add(new BasicNameValuePair("password", password));
        JSONObject json = jsonParser.getJSONFromUrl(loginURL, params);
        // return json
        Log.e("JSON", json.toString());
        return json;
    }

It doesn't work nor give any JSON reply.

But when I changed it into my friend's hosting:

private static String loginURL = "http://novalekaherdinata.cu.cc/android_login_api/";
private static String registerURL = "http://novalekaherdinata.cu.cc/android_login_api/";

It works fine.

Any idea why that happens? I cannot use my friend's hosting, since I need to present it in localhost. Thanks in advance