Async Android Json Parser Android- Null Pointer Exception

From my last post, got t know that, i need to use async task for json parsing from url, have done the same and attached below, public class ReadJson extends ListActivity { private

Solution 1:

It looks like you're using this JSONParser I think. What appears to be happening is that you have a URL that is not producing valid JSON, which is resulting in an Exception being thrown and caught in the class somewhere along the way -- most likely in the jObj = new JSONObject(json); line. The end result is that the returned variable is still null. So when you call json.length() in your loop, you're trying to call length() on a null object. You should do a check on it prior to going into the loop to make sure that it isn't null.

Solution 2:

I think that, you are not getting valid JSON format from server. before parsing check the response getting from your server, Here is snippet of code, here pass url and get yourReponseInJSONStr check response string in logcat is it in proper JSON format or not and then do the operation of parsing.

try {
                HttpClient httpclient = newDefaultHttpClient();
                HttpPost httppost = newHttpPost(
                        url);

            List<NameValuePair> nameValuePairs = newArrayList<NameValuePair>(2);

            httppost.setEntity(newUrlEncodedFormEntity(nameValuePairs));
            ResponseHandler<String> responseHandler = newBasicResponseHandler();

            String yourReponseInJSONStr = httpclient.execute(httppost,
                    responseHandler);

            Log.d("yourReponseInJSONStr ", yourReponseInJSONStr );

                    JSONObject yourJsonObj = newJSONObject(yourReponseInJSONStr);


} catch (Exception e) {
            e.printStackTrace();
        }

you can also continue parsing in this code as well,Hope this helps you,

Solution 3:

Try this for getting json

publicstatic String getJSONString(String url) {
    StringjsonString=null;
    HttpURLConnectionlinkConnection=null;
    try {
        URLlinkurl=newURL(url);
        linkConnection = (HttpURLConnection) linkurl.openConnection();
        intresponseCode= linkConnection.getResponseCode();
        if (responseCode == HttpURLConnection.HTTP_OK) {
            InputStreamlinkinStream= linkConnection.getInputStream();
            ByteArrayOutputStreambaos=newByteArrayOutputStream();
            intj=0;
            while ((j = linkinStream.read()) != -1) {
                baos.write(j);
            }
            byte[] data = baos.toByteArray();
            jsonString = newString(data);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (linkConnection != null) {
            linkConnection.disconnect();
        }
    }
    return jsonString;
}

publicstaticbooleanisNetworkAvailable(Activity activity) {
    ConnectivityManagerconnectivity= (ConnectivityManager) activity
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivity == null) {
        returnfalse;
    } else {
        NetworkInfo[] info = connectivity.getAllNetworkInfo();
        if (info != null) {
            for (inti=0; i < info.length; i++) {
                if (info[i].getState() == NetworkInfo.State.CONNECTED) {
                    returntrue;
                }
            }
        }
    }
    returnfalse;
}

use isNetworkAvailable for checking connection

and i parsed this way

try {

                JSONObject jObjectm = newJSONObject(result);
                JSONObject jObject=jObjectm.getJSONObject("items");
                  if(jObject!=null)
                  {
                    Iterator<?> iterator1=jObject.keys();
                         LinkedHashMap<String,LinkedHashMap<String, Object> > inneritem = newLinkedHashMap<String, LinkedHashMap<String, Object> >();
                        while (iterator1.hasNext() ){
                            Item hashitem=newItem();
                               String key1 = (String)iterator1.next();
                               JSONObject jObject1=jObject.getJSONObject(key1);
                               Iterator<?> iterator=jObject1.keys();
                                 LinkedHashMap<String, Object> inneritem1 = newLinkedHashMap<String, Object>();
                                while (iterator.hasNext() ){


                                    String key =(String) iterator.next();

                                  inneritem1.put(key, jObject1.get(key));


                                }
                                 hashitem.setItem(key1,inneritem1);
                                inneritem.put(key1,inneritem1);
                                arrayOfList.add(hashitem); 
                        }




                  }
                } catch (JSONException e) {

                    System.out.println("NO Json data found");
                }