getting FATAL EXCEPTION in MAIN when doing a callback,asyntask android -

after reading on android asynctask sending callbacks ui goal :

dialog box show when waiting authentication server , long process done, call invoked , dialog box dismissed.

my structure ( asyntask , log in activity separated classes )

1. log in activity
2. class extends aysnctask
3. a call interface.

partial of codes :

public class spalshscreenactivity extends activity implements logincallback{     @override     public void onwindowfocuschanged(boolean hasfocus) {         super.onwindowfocuschanged(hasfocus);         if (hasfocus) {             loginbutton = (button) findviewbyid(r.id.btnlogin);             loginbutton.setbackgrounddrawable(getresources() .getdrawable(r.drawable.button));             loginbutton .setonclicklistener(new view.onclicklistener() {                 @override                 public void onclick(view v) {                     dialog = new progressdialog(spalshscreenactivity.this);                     dialog.setmessage("waiting......");                     dialog.show();                      service client = new service(new spalshscreenactivity(), email.gettext().tostring(), password.gettext().tostring());                     string loginurl = "my url goes here";                      client.execute(loginurl);                 }             });         }     }      @override     public void successfullylogin() {         log.d("splash","successfullylogin");         dialog.dismiss(); // **<--------crash @ here**     }      @override     public void failedtologin() {      } } 

service.java :

public class service extends asynctask<string, integer, string> {     private logincallback callback;     string username;     string password;      public service(logincallback callback, string username, string password) {           this.callback = callback;         this.username = username;         this.password = password;     }     // handling ssl connection protected string doinbackground(string... arg) {     // validation , accept type of self signed certificates     simplesslsocketfactory simplesslfactory;     string  loginurl    =   arg[0];     try {         simplesslfactory = new simplesslsocketfactory(null);          simplesslfactory .sethostnameverifier((x509hostnameverifier) hostnameverifier);          // enable http parameters         params = new basichttpparams();         httpprotocolparams.setversion(params, httpversion.http_1_1);         httpprotocolparams.setcontentcharset(params, http.utf_8);          // register http , https protocols. https, register our         // custom ssl factory object.         schemeregistry registry = new schemeregistry();         registry.register(new scheme("http", plainsocketfactory .getsocketfactory(), 80));         registry.register(new scheme("https", simplesslfactory, 443));          // create new connection manager using newly created registry         // , create new http client         // using connection manager         ccm = new threadsafeclientconnmanager(params, registry);     } catch (keymanagementexception e1) {         // todo auto-generated catch block         e1.printstacktrace();     } catch (unrecoverablekeyexception e1) {         // todo auto-generated catch block         e1.printstacktrace();     } catch (nosuchalgorithmexception e1) {         // todo auto-generated catch block         e1.printstacktrace();     } catch (keystoreexception e1) {         // todo auto-generated catch block         e1.printstacktrace();     }     // todo auto-generated method stub     httpclient client = new defaulthttpclient(ccm, params);      list<namevaluepair> namevaluepair = new arraylist<namevaluepair>(2);     namevaluepair.add(new basicnamevaluepair("user_session[email]", "lenanguyen@hotmail.ca"));     namevaluepair.add(new basicnamevaluepair("user_session[password]","2congato"));      // create http method     httppost login = new httppost(loginurl);      try {         login.setentity(new urlencodedformentity(namevaluepair));     } catch (unsupportedencodingexception e1) {         // todo auto-generated catch block         e1.printstacktrace();     }     // fire request     try {         httpresponse response = client.execute(login);         httpentity entity = response.getentity();          inputstream = entity.getcontent();         this.result = convertstreamtostring(is);      } catch (clientprotocolexception e) {         // todo auto-generated catch block         e.printstacktrace();         log.d("clientprotocolexception ", e.tostring());      } catch (ioexception e) {         // todo auto-generated catch block         e.printstacktrace();         log.d("ioexception ", e.tostring());      }     return result; }      // called after doinbackground finishes     protected void onpostexecute(string result) {            log.e("result, yay!", this.result);         this.callback.successfullylogin();     }  } 

and call interface

public interface logincallback {     void successfullylogin ();     void failedtologin(); } 

however after dialog shows few seconds, app crashing , fatal exception in main thrown in cat log. ideas guys.

ps :

log cat here

change

service client = new service(new spalshscreenactivity(), email.gettext().tostring(), password.gettext().tostring()); 

into

service client = new service(spalshscreenactivity.this, email.gettext().tostring(), password.gettext().tostring()); 

and

public flipgiveclient(logincallback callback, string username, string password) {       this.callback = callback;     this.username = username;     this.password = password; } 

into

public flipgiveclient(activity activity, string username, string password) {       this.callback = (logincallback) activity;     this.username = username;     this.password = password; }