Android, Volley Request, the response is blocking main thread

Question

Something bad is happening when using Volley to treat a large response:

String url = AppHelper.DOMAIN + "/service/pages/profile_update.json";

this.infoTextView.setText(getString(R.string.profile_info_updating));

final StringRequest stringRequest = new StringRequest(Request.Method.POST, url,
        new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                try {
                    JSONObject json = new JSONObject(response);

                    if (json.getBoolean("success")) {
                        // manage JSON object here
                    } else {
                        Toast.makeText(ProfileActivity.this,
                                getString(R.string.connection_problem_server),
                                Toast.LENGTH_LONG).show();
                    }
                } catch (JSONException e) {
                    ProfileActivity.this.infoTextView.setText(
                            getString(R.string.profile_info_updating_error));

                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
        ProfileActivity.this.infoTextView.setText(
                getString(R.string.profile_info_updating_error));

        if (error.networkResponse != null && error.networkResponse.statusCode == 401) {
            Toast.makeText(ProfileActivity.this,
                    getString(R.string.connection_problem_permission),
                    Toast.LENGTH_LONG).show();
        }

        new android.os.Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                if (ProfileActivity.this.swipeRefreshLayout != null) {
                    ProfileActivity.this.swipeRefreshLayout.setRefreshing(false);
                }
            }
        }, 1000);

        error.printStackTrace();
    }
}) {
    @Override
    protected Map<String, String> getParams() {
        Map<String, String> params = new HashMap<>();
        params.put("auth_token", ProfileActivity.this.defaultUser.getAuthenticationToken());
        return params;
    }

    @Override
    public Map<String, String> getHeaders() throws AuthFailureError {
        Map<String, String> params = new HashMap<>();
        params.putAll(super.getHeaders());
        params.put("Accept-Encoding", "gzip,deflate");
        return params;
    }

    @Override
    protected Response<String> parseNetworkResponse(NetworkResponse response) {
        StringBuilder output = new StringBuilder();
        try {
            GZIPInputStream gStream = new GZIPInputStream(new ByteArrayInputStream(response.data));
            InputStreamReader reader = new InputStreamReader(gStream);
            BufferedReader in = new BufferedReader(reader, 16384);

            String read;

            while ((read = in.readLine()) != null) {
                output.append(read).append("\n");
            }
            reader.close();
            in.close();
            gStream.close();
        } catch (IOException error) {
            error.printStackTrace();
            return Response.error(new ParseError());
        }

        return Response.success(output.toString(), HttpHeaderParser.parseCacheHeaders(response));
    }
};

stringRequest.setRetryPolicy(new RetryPolicy() {
    @Override
    public int getCurrentTimeout() {
        // 40 seconds
        return 40000;
    }

    @Override
    public int getCurrentRetryCount() {
        return DefaultRetryPolicy.DEFAULT_MAX_RETRIES;
    }

    @Override
    public void retry(VolleyError error) throws VolleyError {
        throw error;
    }
});

Volley.newRequestQueue(this).add(stringRequest);

this code block the main thread, freezing the application.

Additionally, I set some header values to allow gzip response and a code to handle the data. But it is not the piece that make the undesired behavior. The application freeze only when onResponse(String response) starts.

What can I do to avoid this?

Answer 1

onResponse and onErrorResponse is called on UI thread hence any heavy operation done inside these methods will make you application less responsive. I guess you are trying to parse the response in onResponse() which is incorrect.

You have to move to parsing logic to parseNetworkResponse since this is the method which is called in background thread. Refer the below link for more details :

https://developer.android.com/training/volley/request-custom.html