解决捕获NullPointerException Java的问题

Question

我正在尝试解析JSON，但也允许用户输入部分JSON网址。因此，当网址“看起来”正确但没有任何结果时，会出现这种情况。这会导致NullPointerException。为了阻止我的代码崩溃，我必须抓住这个错误。我知道你不应该这样做，所以有人能告诉我一个更好的方法来解决这个问题吗？抱歉，因为我对Java / Android还不熟悉。

 protected String doInBackground(String... params) {



            ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();


            try {
                String url_select = Final;

                JSONObject json = jParser.makeHttpRequest(url_select,
                        "GET", param);
                 


                articles = json.getJSONObject("primaryTopic");
                regadress = articles.getJSONObject("RegAddress");
                try{
                    town = regadress.getString("PostTown");
                }

                catch (JSONException e2){
                    Log.e("JSONException", e2.toString());
                    town = regadress.getString("AddressLine2");
                }
                title = articles.getString("CompanyName");
                description = articles.getString("CompanyStatus");


            }
            catch (java.lang.NullPointerException e) {
                Log.e("NullPointerException", e.toString());
                progressDialog.dismiss();
                //showButtonDialog();
            }
            catch (IllegalStateException e3) {
                Log.e("IllegalStateException", e3.toString());
                e3.printStackTrace();
            }
            catch (JSONException e5) {
                progressDialog.dismiss();
                //showButtonDialog();
                Log.e("JSONException", e5.toString());
                e5.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            try {

                String newTitle = Html.fromHtml(title).toString();
                txtTitle.setText(newTitle);
                String newDesc = Html.fromHtml(description).toString();
                txtDesc.setText(newDesc);
                String newTown = Html.fromHtml(town).toString();
                txtTown.setText(newTown);

                progressDialog.dismiss();
            } catch (Exception e) {
                Log.e("JSONException", "Error: " + e.toString());

            }
        }