Android :: Android's Listview - Update View Within Of Cells Just After Invalidating Activity's View

I have ListViewActivity
public class SelectActivity extends ListActivity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.select_one_of);
SimpleAdapter adapter = new SimpleAdapter(
this,
createChildList(),
R.layout.select_one_of_childrow,
new String[] { KEY_VALUE },
new int[] { R.id.selectoneof_add_new_item});
setListAdapter(adapter);
}
// ...
}

after setListAdapter() calls I would like to execute the following code:

((TextView) getListView().getChildAt(0).findViewById(R.id.selectoneof_add_new_item)).setCompoundDrawablesWithIntrinsicBounds(0, 0, R.drawable.ticked, 0); but getListView().getChildAt(xxx) returns null and I catch NullPointerException. Where should I put mentioned above code-snippet?