动态生成菜单的一段还末理解的代码

这段代码暂时看不太懂，先记下来。等看了intent的内容后再回头看。 

  @Override

    public boolean onPrepareOptionsMenu(Menu menu) {

        super.onPrepareOptionsMenu(menu);

        final boolean haveItems = getListAdapter().getCount() > 0;

        // If there are any notes in the list (which implies that one of

        // them is selected), then we need to generate the actions that

        // can be performed on the current selection.  This will be a combination

        // of our own specific actions along with any extensions that can be

        // found.

        if (haveItems) {

            // This is the selected item.

            Uri uri = ContentUris.withAppendedId(getIntent().getData(), getSelectedItemId());

            // Build menu...  always starts with the EDIT action...

            Intent[] specifics = new Intent[1];

            specifics[0] = new Intent(Intent.ACTION_EDIT, uri);

            MenuItem[] items = new MenuItem[1];

            // ... is followed by whatever other actions are available...

            Intent intent = new Intent(null, uri);

            intent.addCategory(Intent.CATEGORY_ALTERNATIVE);

            menu.addIntentOptions(Menu.CATEGORY_ALTERNATIVE, 0, 0, null, specifics, intent, 0,

                    items);

            // Give a shortcut to the edit action.

            if (items[0] != null) {

                items[0].setShortcut('1', 'e');

            }

        } else {

            menu.removeGroup(Menu.CATEGORY_ALTERNATIVE);

        }

        return true;

    }