CheckBox in ListView being reset when it leaves the screen

Question

I have followed the tutorial here to create a custom ListView that shows items with category headers. I have modified the list_item_entry.xml to put a

Answer 1

class Item{
 boolean isSection;
 String title;
 boolean isOptionChecbox;

 //your getter/setter

    @Override
    public String toString() {
        return title;
    }
}

you Adapter:
public class listAdapter extends ArrayAdapter {

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    final Item i = items.get(position);
    if(i.isSection()){
              convertView = vi.inflate(R.layout.list_item_section, parent, false);
              convertView.setOnClickListener(null);
              convertView.setOnLongClickListener(null);
              convertView.setLongClickable(false);
              final TextView sectionView = (TextView) convertView.findViewById(R.id.list_item_section_text);
              sectionView.setText(si.getTitle());
       } else{
              convertView = vi.inflate(R.layout. list_item_entry, parent, false);
              final TextView title = (TextView) convertView.findViewById(R.id.list_item_entry_title);
              if (title != null) title.setText(ei.getTitle());

              CheckBox optionCheckbox = (CheckBox) convertView.findViewById(R.id.option_checkbox);
              optionCheckbox.setChecked(ei.isOptionCheckbox());
              optionCheckbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
                  @Override
                  public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
                      item.setOptionCheckbox(b);
                  }
            });
       }      
    return convertView;
 }

}