android - Adapter not getting updated when a value of a view is updated in listview -

i'm using listview show list of elements need count things. list view looks

the value "3" gets updated when click on plus , minus button or reset button. how achieve in customlistviewadapter

holder.plusbutton.setonclicklistener(new onclicklistener() {          @override         public void onclick(view v) {             viewgroup parent = (viewgroup) v.getparent();             textview tv = (textview) parent.findviewbyid(r.id.count);              int count = integer.parseint((string) tv.gettext());             count++;             tv.settext(string.valueof(count));             int currentval = integer.parseint(totalcount.gettext().tostring());             totalcount.settext(string.valueof(currentval + 1));         }     }); 

where i'm using viewholder pattern.

now problem is, after update value, it's not getting updated in adapter. i.e when try loop on adapter, still value 3 set rather updated value. doing right way or there better way of doing it. how make sure adapter has updated value.

2nd question: adapter not getting updated, when i'm trying retrieve values list send somewhere, nullpointer when

view = listview.getchildat(i).findviewbyid(r.id.count); 

for views in list not visible on screen. i.e if have 10 such rows, 5 visible on screen , when try access 6th, null pointer above code block. how should accessing listview values then?

edit: getview method source code is

public view getview(int position, view convertview, viewgroup parent) {     viewholder holder = null;     counter rowitem = getitem(position);      layoutinflater minflater = (layoutinflater) context             .getsystemservice(activity.layout_inflater_service);      if (convertview == null) {         convertview = minflater.inflate(r.layout.counter_list, null);         holder = new viewholder();          convertview.findviewbyid(r.id.parentlayoutrow).setbackgroundcolor(color.parsecolor(rowitem.getprimarycolor()));          holder.resetbutton = (button) convertview.findviewbyid(r.id.buttonreset);         holder.countername = (textview) convertview.findviewbyid(r.id.countername);         holder.counterdesc = (textview) convertview.findviewbyid(r.id.counterdesc);         holder.count = (textview) convertview.findviewbyid(r.id.count);         holder.minusbutton = (button) convertview.findviewbyid(r.id.buttonminus);         holder.plusbutton = (button) convertview.findviewbyid(r.id.buttonplus);          convertview.settag(holder);     } else {         holder = (viewholder) convertview.gettag();     }      holder.resetbutton.setonclicklistener(new onclicklistener() {          @override         public void onclick(view v) {             viewgroup parent = (viewgroup) v.getparent();             textview tv = (textview) parent.findviewbyid(r.id.count);              int currentval = integer.parseint(totalcount.gettext().tostring());             totalcount.settext(string.valueof(currentval - integer.parseint(tv.gettext().tostring())));              tv.settext(string.valueof(0));         }     });     holder.countername.settext(rowitem.getname());     holder.counterdesc.settext(rowitem.getdesc());     holder.count.settext(string.valueof(rowitem.getcount()));     holder.resetbutton.setbackgroundcolor(color.parsecolor(rowitem.getbuttoncolor()));     holder.minusbutton.setbackgroundcolor(color.parsecolor(rowitem.getbuttoncolor()));     holder.minusbutton.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {             viewgroup parent = (viewgroup) v.getparent();             textview tv = (textview) parent.findviewbyid(r.id.count);              int count = integer.parseint((string) tv.gettext());              if (count > 0) {                 count--;                 tv.settext(string.valueof(count));                 int currentval = integer.parseint(totalcount.gettext().tostring());                 totalcount.settext(string.valueof(currentval - 1));             }          }     });     holder.plusbutton.setbackgroundcolor(color.parsecolor(rowitem.getbuttoncolor()));     holder.plusbutton.setonclicklistener(new onclicklistener() {          @override         public void onclick(view v) {             viewgroup parent = (viewgroup) v.getparent();             textview tv = (textview) parent.findviewbyid(r.id.count);              int count = integer.parseint((string) tv.gettext());             count++;             tv.settext(string.valueof(count));             int currentval = integer.parseint(totalcount.gettext().tostring());             totalcount.settext(string.valueof(currentval + 1));         }     });      return convertview; } 

now how update adapter value in function holder.minusbutton.setonclicklistener(new onclicklistener()

the views in listview don't retain state. viewholder shows thrown away when leave screen , rebuilt later: driven value in adapter.

so want find entry in adapter backing list , update that, have listview redraw itself. have @ listview.getadapter(), adapter.getitem(). you'll note there's no adapter.setitem(), , can't change value of existing string or integer (they're immutable) list item needs object wraps value. or use atomicinteger has increment method. need call listview.notifydatasetchanged() doesn't inspect inside wrapper object.