Widget _itemBuilder(BuildContext context, int index) {
    Menu myMenu = Menu(menu[index]);
    return new ListTile(
      leading: new Text("-"),
      title: new Text("Comando ${myMenu.name}"),
      onTap: <myMneu.command>,
    );
  }

{
   "menu": [
      {
         "id": 1,
         "name": "Start",
         "command": "StartScreen()"
      },
      {
         "id": 2,
         "name": "Pause",
         "command": "PauseScreen()"
      },
      {
         "id": 3,
         "name": "Finish",
         "command": "FinishScreen()"
      }
   ]
}