java - Android app crashes creating opening Intent -

my android app "e-mail" crashes when try open "readactivity".

the method openmail(), declared in mainactivity, should start readactivity:

public void openmail(view v, int index) {     string[] mail = {"x", "y", "z"};      intent readintent = new intent(this, readactivity.class); <-- error occurs here      readintent.putextra("mail", mail);      startactivity(readintent); } 

the method called in listviewadapter:

@override public view getview(final int position, view convertview, viewgroup parent) {     holder holder = new holder();      view rowview = inflater.inflate(r.layout.listview_item, null);      holder.imageview = (imageview) rowview.findviewbyid(r.id.imageview);     holder.txvsendermail = (textview) rowview.findviewbyid(r.id.txvsender);     holder.txvsubject = (textview) rowview.findviewbyid(r.id.txvsubject);      holder.imageview.setimageresource(imageid[position]);     holder.txvsendermail.settext(sendermail[position]);     holder.txvsubject.settext(subject[position]);      rowview.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {             new mainactivity().openmail(v, position);         }     });      return rowview; } 

the error: java.lang.nullpointerexception: attempt invoke virtual method 'android.app.activitythread$applicationthread android.app.activitythread.getapplicationthread()' on null object reference

i hope can me! thank you!

you trying create new mainactivity when do

new mainactivity().openmail(v, context, position); 

i think wanted this, if @ mainactivity class:

getactivity().openmail(v, context, position); 

of course, dont forget add readactivity androidmanifest