Why does this Volley request generates an IllegalStateException

Question

I am trying to pull a JSON array and load it into a RecyclerView. here is the code :

JsonArrayRequest TweetReq = new JsonArrayRequest(URL1,
            new Response.Listener<JSONArray>()
            {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d("WORKING RESPONSE:::::", response.toString());
                    //hidePDialog();

                    SharedPreferences Tempx = getSharedPreferences("ActivitySession", Context.MODE_PRIVATE);
                    SharedPreferences.Editor edx = Tempx.edit();
                    edx.putString("GSON_FEED", response.toString());
                    edx.apply();

                    Gson gson = new Gson();
                    JsonParser parser = new JsonParser();
                    JsonArray jArray = parser.parse(Tempx.getString("GSON_FEED","")).getAsJsonArray();

                    //ArrayList<MainPojo> uid = new ArrayList<MainPojo>();

                    for(JsonElement obj : jArray )
                    {
                        MainPojo cse = gson.fromJson( obj , MainPojo.class);
                        TweetList.add(cse);

                    }
                    mAdapter.notifyDataSetChanged();

                    // Parsing json

                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error)
        {
            SharedPreferences Tempx = getSharedPreferences("ActivitySession", Context.MODE_PRIVATE);

            try{Gson gson = new Gson();
                JsonParser parser = new JsonParser();
                JsonArray jArray = parser.parse(Tempx.getString("GSON_FEED","")).getAsJsonArray();



                for(JsonElement obj : jArray )
                {
                    MainPojo cse = gson.fromJson( obj , MainPojo.class);
                    TweetList.add(cse);

                }
                mAdapter.notifyDataSetChanged();


                VolleyLog.d("EDUKNOW::::", "Error: " + error.getMessage());
            }
            catch (Exception e)
            {
                e.printStackTrace();
            }



        }
    });

As you can see, I am storing the result into a SharedPreferences and populating it!

However, when I execute it, all the time onErrorResponse() is getting executed, here is the logcat:

01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:java.lang.IllegalStateException: This is not a JSON Array. 
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atcom.google.gson.JsonElement.getAsJsonArray(JsonElement.java:106) 
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atcom.fossasia.loklak.Activities.MainActivity$2.onErrorResponse(MainActivity.java:105)
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atcom.android.volley.Request.deliverError(Request.java:564) 
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atcom.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:101)
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atandroid.os.Handler.handleCallback(Handler.java:739) 
01-08 20:01:08.688 4764-4764/com.fossasia.loklak W/System.err:     atandroid.os.Handler.dispatchMessage(Handler.java:95) 
01-08 20:01:08.689 4764-4764/com.fossasia.loklak W/System.err:     atandroid.os.Looper.loop(Looper.java:148) 
01-08 20:01:08.689 4764-4764/com.fossasia.loklak W/System.err:     atandroid.app.ActivityThread.main(ActivityThread.java:5417) 
01-08 20:01:08.689 4764-4764/com.fossasia.loklak W/System.err:     atjava.lang.reflect.Method.invoke(Native Method) 
01-08 20:01:08.689 4764-4764/com.fossasia.loklak W/System.err:     atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
01-08 20:01:08.689 4764-4764/com.fossasia.loklak W/System.err:     atcom.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

he first error, This is not a JSON Array , I guess is because its trying to load from sharedPreferences which is empty initially.

And my question is : Is this due to any problem in the API or the way I've defined my POJO?

Answer 1

I think it the problem lies in your POJO implementation. I checked your query from http://loklak.org/api/search.json?q=apple

The response is not a JSON Array, it's a JSON Object. See the beginning of the response? it starts with a curly bracket {, which marks the beginning of an object. I suggest you read a bit on the JSON documentation .

In order to get your JSON Array, you need to check the structure of your JSON. I copy-pasted the JSON response to an Online JSON Formatter and I can see there are 7 objects there, with one of them containing the JSON Array that you need. If you manage to get that JSON Object as a JSON Array, you'll be able to use it.

1. Change JSONArrayRequest to a JSONObjectRequest
2. Get the JSONArray inside the JSONObject (in this case, the key is "statuses", and the value is a JSONArray)
3. Parse the JSONArray

Good Luck