Gson을 사용하여 목록 객체 JSON 구문 분석

Google Gson 라이브러리로 Json을 구문 분석하려고하는데 현재 작동하지 않습니다 ...

다음은 내가 가져야 할 Json입니다.

{
"shoppingLists": [
    {
        "ShoppingList": {
            "id": "51",
            "name": "loool",
            "created": "2014-03-22 13:03:22",
            "modified": "2014-03-22 13:03:22"
        },
        "ShoppingItem": [
            {
                "id": "24",
                "shopping_item_category_id": "19",
                "name": "Biscuits",
                "description": "",
                "created": "2014-02-05 17:43:45",
                "modified": "2014-02-05 17:43:45",
                "category_name": "Confiseries \/ Gouters"
            },
            {
                "id": "25",
                "shopping_item_category_id": "19",
                "name": "Snickers",
                "description": "",
                "created": "2014-02-05 17:44:08",
                "modified": "2014-02-05 17:44:08",
                "category_name": "Confiseries \/ Gouters"
            },
            {
                "id": "26",
                "shopping_item_category_id": "19",
                "name": "C\u00e9reales",
                "description": "",
                "created": "2014-02-05 17:44:57",
                "modified": "2014-02-05 17:44:57",
                "category_name": "Confiseries \/ Gouters"
            }
        ]
    }
 ]
}

내 모델은 다음과 같습니다.

shoppingLists :

public class shoppingLists {
        public ShoppingList ShoppingList;
        public List<ShoppingItem> ShoppingItems;
}

쇼핑리스트 :

public class ShoppingList {
public int id;
public String name;
public String created;
public String modified;
}

ShoppingItem :

public class ShoppingItem {
public int id;
public int shopping_item_category_id;
public String name;
public String description;
public String created;
public String modified;
public String category_name;
}

다음은 서버에서 Json을 가져 오는 AsyncTask입니다.

public class APIRetrieveLists extends AsyncTask<APIRequestModel, Void, List<shoppingLists>>{

SQLHelper _sqlHelper = null;
Context _context;
ProgressBar _pb;

public APIRetrieveLists(Context context, ProgressBar pb){
    this._context = context;
    this._pb = pb;
}


@Override
protected void onPreExecute(){
}

@Override
protected void onPostExecute(List<shoppingLists> model){
    this._sqlHelper = new SQLHelper(this._context);
    if (model != null){
        for (shoppingLists cn : model){
            Log.i("infos", "list's name => " + cn.ShoppingList.name);
        }
    }else{
        Log.i("infos", "model is null");
    }
}

@Override
protected List<shoppingLists> doInBackground(APIRequestModel... arg0) {
    APIRequestModel model = arg0[0];
    try
    {
        try
        {
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
            nameValuePairs.add(new BasicNameValuePair("access_token", model.getToken()));
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://apiurl/index.json");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8));
            HttpResponse response = httpclient.execute(httppost);
            BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
            String s = "";
            String all = "";
            while ((s = reader.readLine()) != null){
                all += s;
            }
            Gson gson = new Gson();
            List<shoppingLists> Obj = (List<shoppingLists>) gson.fromJson(all, new TypeToken<List<shoppingLists>>(){}.getType());
            return (Obj);
        } 
        catch (ClientProtocolException e) {
            Log.i("infos", "first");
            return (null);
        } 
    }
    catch (Exception e){
        Log.i("infos", "second");
        return (null);
    }
}
}

예외 "second"는 항상 발생합니다 ... Log.i ( "infos", "model is null"); 또한 실행됩니다. 누군가 도울 수 있다면 :) 감사합니다! 문안 인사.