MainActivity.java

private void loadKeitaroUrl(String keitaroUrl) {
        Log.w("debug", "Requiring... " + keitaroUrl);
        StringRequest stringRequest = new StringRequest(Request.Method.GET, keitaroUrl,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        Log.d("debug", "Successful response " + response);
                        parseData(response);
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.w("debug", "Request is failed");
                webView.loadUrl(WHITE_PAGE_URL);
            }
        });
        RequestQueue queue = Volley.newRequestQueue(this);
        queue.add(stringRequest);
    }

    private void parseData(String response) {
        try {
            JSONObject jsonObject = new JSONObject(response);
            String url = jsonObject.getString("url");
            String showIn = jsonObject.getString("showIn");

            if (showIn.equals("webView")) {
                if (url.equals(WHITE_PAGE_URL)) {
                    SharedPreferences.Editor editor = sharedPreferences.edit();
                    editor.putBoolean(SHOW_WHITE_PAGE.toString(), true);
                    editor.apply();
                    Log.w("debug", "Saved url: " + url);
                } else {
                    subscribeInOneSignal();
                }
                Log.w("debug", "Got url: " + url);
                webView.loadUrl(url);
            } else if (showIn.equals("browser")) {
                Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                startActivity(browserIntent);
            } else {
                webView.loadUrl(WHITE_PAGE_URL);
            }

        } catch (JSONException e) {
            Log.e("parseDataError", e.getMessage());
            e.printStackTrace();
            webView.loadUrl(WHITE_PAGE_URL);
        }
    }