android: Listview -set visibility of checkboxes in all the listitems

ListView list=getListView();
int count = list.getChildCount();
for (int i = 0; i < count; i++) {
   View child = list.getChildAt(i);
   CheckBox cb11=(CheckBox)child.findViewById(R.id.checkBox1);
  cb11.setVisibility(View.VISIBLE);
}