title: How can I fix RadioListTile list in flutter?
body: <p>I have a list like that
  List itemList = [
  IdText(1,'hello'),
  IdText(2,'hallo'),
  IdText(3,'ciao')
  ];
  and I want to do a radiolisttile; I show the text and I save the ids in map.But I have an error(selected button not colored), How can I fix this?
  here is the my code below:</p>
  
  <pre><code>             for(IdText list in itemList)
                   RadioListTile(
                     title: Text(list.text),
                     groupValue: _map[item.fieldName],
                     onChanged: (value) {
                       setState(() {
                         _map[item.fieldName]  = value.id;
                       });
                       print(_map[item.fieldName] );
                     },
                     value: list,
                   ), 
  </code></pre>