java - Handle Exception with error dialog in asynctask -

i making rss android app pull reload. want use asynctask. here code:

class refresh extends asynctask<string,void,void>{      @override     protected void doinbackground(string... params) {         try {             download(getresources().getstring(r.string.link));         }catch (exception e){             createneterrordialog();          }         return null;     }      @override     protected void onpostexecute(void avoid) {         super.onpostexecute(avoid);         try{             views();         }catch (exception e){             toast.maketext(mainactivity.this,                     "error",                     toast.length_long).show();             cancel(true);         }          lstpost.setonitemclicklistener(new adapterview.onitemclicklistener() {             @override             public void onitemclick(adapterview<?> parent, view view, int position,                                     long id) {                 intent intent = new intent(mainactivity.this, webviewactivity.class);                 bundle bundle = new bundle();                  document xmlfeed = rssfeed                         .getrssfromserver(getresources().getstring(r.string.link));                 nodelist nodes = xmlfeed.getelementsbytagname(getresources().getstring(r.string.item));                 element item = (element) nodes.item(position);                 string summary = rssfeed.getvalue(item, key_summary);                 string title = rssfeed.getvalue(item, key_title);                 bundle.putstring(getresources().getstring(r.string.tag_summary), summary);                 bundle.putstring(getresources().getstring(r.string.tag_title), title);                 intent.putextras(bundle);                 startactivity(intent);             }         });     } }     void download(string url) throws exception{     lists.clear();          document xmlfeed = rssfeed.getrssfromserver(url);         nodelist nodes = xmlfeed.getelementsbytagname("entry");         (int = 0; < nodes.getlength(); i++) {             element item = (element) nodes.item(i);             hashmap<string, object> feed = new hashmap<string, object>();             feed.put(key_title, rssfeed.getvalue(item, key_title));             feed.put(key_summary, rssfeed.getvalue(item, key_summary));             feed.put(key_link, rssfeed.getvalue(item, key_link));             //feed.put(key_date, rssfeed.getvalue(item, key_date));             post_lists.add(feed);             lists.add(feed.get(key_title).tostring());         }  }   void views(){     lstpost = (listview) findviewbyid(r.id.lstposts);      adapter = new arrayadapter<string>(this,             android.r.layout.simple_list_item_2, android.r.id.text1, lists) {          @override         public view getview(int position, view convertview, viewgroup parent) {             view view = super.getview(position, convertview, parent);             textview txt1 = (textview) view                     .findviewbyid(android.r.id.text1);             textview txt2 = (textview) view                     .findviewbyid(android.r.id.text2);             hashmap<string, object> data = post_lists.get(position);             txt1.settext(html.fromhtml(data.get(key_title).tostring()));              if (data.get(key_summary).tostring().length() > 125) {                  txt2.settext(html.fromhtml((data.get(key_summary).tostring()).substring(0, 125) + "..."));             } else {                  txt2.settext(html.fromhtml(data.get(key_summary).tostring()));             }             return view;         }      };      textview dateview=(textview) findviewbyid(r.id.date);     calendar rightnow = calendar.getinstance();     dateformat formatter = new simpledateformat(getresources().getstring(r.string.date_format));      dateview.settext(getresources().getstring(r.string.lastupdate) + formatter.format(rightnow.gettime()));     lstpost.setadapter(adapter); }   protected void createneterrordialog() {      alertdialog.builder builder = new alertdialog.builder(this);     builder.setmessage(getresources().getstring(r.string.errorbox))             .settitle("unable connect")             .setcancelable(false)             .setpositivebutton("settings",                     new dialoginterface.onclicklistener() {                         public void onclick(dialoginterface dialog, int id) {                             intent = new intent(settings.action_wireless_settings);                             startactivity(i);                         }                     }             )             .setneutralbutton("refresh",                     new dialoginterface.onclicklistener() {                         public void onclick(dialoginterface dialog, int id) {                             new refresh().execute(getresources().getstring(r.string.link));                         }                     })             .setnegativebutton("cancel",                     new dialoginterface.onclicklistener() {                         public void onclick(dialoginterface dialog, int id) {                             finish();                         }                     }             );     alertdialog alert = builder.create();     alert.show(); } 

problem: if switch network connection off, app exits instead of displaying createneterrordialog(). can please me out on here?

use below method check whether net on or off:

 public static boolean isdeviceonline(context context) {      connectivitymanager connmgr = (connectivitymanager) context.getsystemservice(context.connectivity_service);     networkinfo networkinfo = connmgr.getactivenetworkinfo();     boolean isonline = (networkinfo != null && networkinfo.isconnected());     if(!isonline)         toast.maketext(context, " no internet connection ", toast.length_short).show();      return isonline; } 

and when need tto check if device online call it:

if(isdeviceonline(context)) { //call refresh } else { //whatever want } 

i thing exception handling not practice it.