Android Async Task Do in Background Error -

am trying create activity connects database on local host, after user fills form form submitted localhost using asyntask.do in background method. getting error , not quite sure wrong, please need help.

this logcat

  `01-30 06:03:10.451: e/androidruntime(1332): fatal exception: asynctask #1     01-30 06:03:10.451: e/androidruntime(1332): java.lang.runtimeexception: error occured while executing doinbackground() 01-30 06:03:10.451: e/androidruntime(1332):     @ android.os.asynctask$3.done(asynctask.java:278) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.futuretask$sync.innersetexception(futuretask.java:273) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.futuretask.setexception(futuretask.java:124) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.futuretask$sync.innerrun(futuretask.java:307) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.futuretask.run(futuretask.java:137) 01-30 06:03:10.451: e/androidruntime(1332):     @ android.os.asynctask$serialexecutor$1.run(asynctask.java:208) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.threadpoolexecutor.runworker(threadpoolexecutor.java:1076) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.threadpoolexecutor$worker.run(threadpoolexecutor.java:569) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.lang.thread.run(thread.java:856) 01-30 06:03:10.451: e/androidruntime(1332): caused by: java.lang.nullpointerexception 01-30 06:03:10.451: e/androidruntime(1332):     @ com.oose.buddiev2.registeractivity$createnewuser.doinbackground(registeractivity.java:101) 01-30 06:03:10.451: e/androidruntime(1332):     @ com.oose.buddiev2.registeractivity$createnewuser.doinbackground(registeractivity.java:1) 01-30 06:03:10.451: e/androidruntime(1332):     @ android.os.asynctask$2.call(asynctask.java:264) 01-30 06:03:10.451: e/androidruntime(1332):     @ java.util.concurrent.futuretask$sync.innerrun(futuretask.java:305) 01-30 06:03:10.451: e/androidruntime(1332):     ... 5 more` 

this async task in activity

class createnewuser extends asynctask<string, string, string> {      /**      * before starting background thread show progress dialog      * */     @override     protected void onpreexecute() {         super.onpreexecute();         pdialog = new progressdialog(registeractivity.this);         pdialog.setmessage("creating user..");         pdialog.setindeterminate(false);         pdialog.setcancelable(true);         pdialog.show();     }      /**      * creating user      * */     protected string doinbackground(string... args) {          string usernamestring = usernameedittext.gettext().tostring();         string emailstring = emailedittext.gettext().tostring();         string passwordstring = passwordedittext.gettext().tostring();          // building parameters         list<namevaluepair> params = new arraylist<namevaluepair>();         params.add(new basicnamevaluepair("username", usernamestring));         params.add(new basicnamevaluepair("email", emailstring));         params.add(new basicnamevaluepair("password", passwordstring));          // getting json object         // note create product url accepts post method         jsonobject json = jsonparser.makehttprequest(url_create_user,                 "post", params);          // check logcat response         log.d("create response", json.tostring());          // check success tag         try {             int success = json.getint(tag_success);             // int success = 1;              if (success == 1) {                 // created product                 intent = new intent(getapplicationcontext(),                         loginactivity.class);                 startactivity(i);                  // closing screen                 finish();             } else {                 // failed create product             }         } catch (jsonexception e) {             e.printstacktrace();         }          return null;     }      /**      * after completing background task dismiss progress dialog      * **/     protected void onpostexecute(string file_url) {         // dismiss dialog once done         pdialog.dismiss();     } 

you cannot in doinbackground.

try removing doinbackground or can put in onpostexecute():

startactivity(i); finish();