Unable To Display Json Data

I am trying to display json array which is inside a json object but nothing is displaying on the text view. I debugged and found that info.java class is working fine. If i am passi

Solution 1:

JSON parsing is OK but you can't retrieve your data like this because you used Volley in asynchronous mode. It means that you can't assume that data will be retrieved as soon as you put the request in the queue. Maybe the queue is very long and your request can be sent later. So, when you tried to retrieve your data, you've seen that your arrayList is null, and it's normal. To deal with the asynchronous way, you have to tell Volley : "tell me when you've retrieved data". And you can do this with a listener.

Here is an example.

publicinterfaceListener {

    voidonDataReceived(ArrayList<Info> list);
    voidonError(int error);
}

BackgroundTask

publicclassBackgroundTask {
    Context context;
    ArrayList<Info> arrayList;
    Listener mListener; // listener to retrieve dataString json_url = "http://cc97cf60.ngrok.io/api/note/";

    publicBackgroundTask(Context context, Listener listener) {
        this.context = context;
        mListener = listener;
    }

    publicvoidgetArrayList() { // no return needed

        arrayList = newArrayList<>();
        JsonObjectRequest jsonObjectRequest = newJsonObjectRequest(Request.Method.GET, json_url, null,
                newResponse.Listener<JSONObject>() {
                    @OverridepublicvoidonResponse(JSONObject response) {
                        JSONArray jsonArray;
                        try {
                            jsonArray = response.getJSONArray("objects");
                            int i;
                            for (i = 0; i < jsonArray.length(); i++) {
                                JSONObject jsonObject = (JSONObject) jsonArray.get(i);
                                /*     Uri b = Uri.parse(jsonObject.getString("image")); //Type casting string to uri*/String a = jsonObject.getString("title");
                                String b = jsonObject.getString("body");
                                Info info = newInfo(a, b);
                                arrayList.add(info);

                            }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                        // if listener has been set, send dataif (mListener != null) {
                            mListener.onDataReceived(arrayList);
                        }
                    }
                }, newResponse.ErrorListener() {
            @OverridepublicvoidonErrorResponse(VolleyError error) {
                // if listener has been set, send errorif (mListener != null) {
                    mListener.onError(error.networkResponse.statusCode);
                }
            }
        });
        Singleton.getInstance(context).addToRequestQueue(jsonObjectRequest);
    }
}

In your MainActivity :

@OverrideprotectedvoidonCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    recyclerView = findViewById(R.id.recycler);
    layoutManager = newLinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setHasFixedSize(true);
    backgroundTask = newBackgroundTask(this, newListener() {
        @OverridepublicvoidonDataReceived(ArrayList<Info> list) {
            thugAdapter = newThugAdapter(list);
            recyclerView.setAdapter(thugAdapter);
        }

        @OverridepublicvoidonError(int error) {

        }
    });
    backgroundTask.getArrayList();
}

And that is !