CODEWITHSUNDEEP
androidandroid-volleysynchronousandroid-networking
Ankur Gupta
Ankur Gupta

Reputation: 410

Volley - Make request wait for previous request to complete

I'm trying to get url of image from json then using that url to download a image. But the problem is url gets fetched so late/slow that imagerequest reports urlFull is null. Even after using DataCallback interface. Any solution for this so that both request happen synchronously?

Edit- One strange thing I noticed is this code works perfectly when I click on button second time. But in first time it says Bad url null

I have set onclicklistener on a button which calls-

public void fetchSave(String photoJson) {
    fetchData(new DataCallback() {
        @Override
        public void onBitmapSuccess(Bitmap result) {
            Utils utils = new Utils(getActivity());
            utils.saveImageSDCard(result);
        }

        @Override
        public void onJsonSuccess(JSONObject result) {
            try {
                JSONArray mediaContentArray = result.getJSONObject(TAG_ENTRY).getJSONObject(TAG_MEDIA_GROUP).getJSONArray(TAG_MEDIA_CONTENT);
                JSONObject mediaObject = (JSONObject) mediaContentArray.get(0);
                urlFull = mediaObject.getString(TAG_IMG_URL);
            } catch (JSONException e) {
                e.printStackTrace();
            }
            Log.d(TAG, "Full image url " + urlFull);
        }
    }, photoJson);
}

fetchData() is as follows-

public void fetchData(final DataCallback callback, String photoJson) {
    RequestFuture<JSONObject> future = newFuture();
    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, photoJson, null, new Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            Log.d(TAG, "JsonObject response= "+response.toString());
            callback.onJsonSuccess(response);

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Toast.makeText(getActivity(), getString(R.string.toast_unknown_error), Toast.LENGTH_LONG).show();
        }
    });

    jsonObjectRequest.setShouldCache(false);
    AppController.getInstance().addToRequestQueue(jsonObjectRequest);
    AppController.getInstance().getRequestQueue().getCache().remove(photoJson);


        final ImageRequest imageRequest = new ImageRequest(urlFull, new Response.Listener<Bitmap>() {
            @Override
            public void onResponse(Bitmap response) {
                Log.d(TAG, "Bitmap response");
                callback.onBitmapSuccess(response);
            }
        }, 0, 0, ImageView.ScaleType.CENTER_CROP, null, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(getActivity(), "Couldn't Download", Toast.LENGTH_SHORT).show();
                error.printStackTrace();

            }
        });
        AppController.getInstance().addToRequestQueue(imageRequest);
}

Upvotes: 0

Views: 775

Answers (2)

EtherPaul
EtherPaul

Reputation: 423

You can send second request in first request's onResponse() method so you will be sure that data is not null

Upvotes: 1

harshithdwivedi
harshithdwivedi

Reputation: 1421

Volley supports blocking request via RequestFutures. You create a normal request but set its callbacks as your request future, which is just volley's extension of a standard java futures. The call to future.get() will block.

It looks something like this

RequestFuture<JSONObject> future = RequestFuture.newFuture();
JsonObjectRequest request = new JsonObjectRequest(Method.POST, SIGNUP_URL, reqBody, future, future)
volleyRequestQueue.add(request);

try {
    JSONObject response = future.get();
} catch (InterruptedException e) {
} catch (ExecutionException e) {
}

Upvotes: 0

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