How do you implement context menu in a ListActivity on Android?

registerForContextMenu(getListView());

AdapterView.AdapterContextMenuInfo info;
try {
    info = (AdapterView.AdapterContextMenuInfo) menuInfo;
} catch (ClassCastException e) {
    Log.e(TAG, "bad menuInfo", e);
    return;
}
long id = getListAdapter().getItemId(info.position);

menu.add(0, MENU_ITEM_ID, 0, R.string.menu_string);

try {
    info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo();
} catch (ClassCastException e) {
    Log.e(TAG, "bad menuInfo", e);
    return false;
}
long id = getListAdapter().getItemId(info.position);