Apps Display Kurdish and arabic text instead of ? marks in android

[opaxweb]

I am developing an android app that displays text in 3 languages - english, kurdish and arabic. The data is fetched from the server using a php script which encodes the data as json.

$subcat_id = mysql_real_escape_string(intval($_GET["id"]));
$query = mysql_query("select * from subcategory where category_id = $subcat_id")or die(mysql_error());
while($row = mysql_fetch_assoc($query))
$output[]=$row;
print(json_encode($output));

The above is the script that fetches data. The mysql server that contains the data uses utf8 encoding. I have also modified the code in java to accept utf8 encoded strings-

public static String executeHttpGet(String url) throws Exception {
        BufferedReader in = null;
        try {
            HttpClient client = getHttpClient();
            HttpGet request = new HttpGet();
            request.setURI(new URI(url));
            HttpResponse response = client.execute(request);
//          in = new BufferedReader(new InputStreamReader(response.getEntity()
//                  .getContent()));
            in = new BufferedReader(new InputStreamReader(response.getEntity()
                    .getContent(), "UTF-8"));
            StringBuffer sb = new StringBuffer("");
            String line = "";
            String NL = System.getProperty("line.separator");

            while ((line = in.readLine()) != null) {
                sb.append(line + NL);
            }

            in.close();

            String result = sb.toString();

            return result;
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    Log.e("log_tag", "Error converting result " + e.toString());
                    e.printStackTrace();
                }
            }
        }
    }

What could be wrong in the whole process? Thanks in advance.