title: Flutter onChanged does not get called for any widget
body: <p>I have implemented RadioButtons in my Flutter Project and the onChanged for those RadioButtons does not get Called. I tried the same thing with TextField and CheckBox which didn't work either</p>
  
  <pre><code>main() =&gt; runApp(MyApp());
  
  class MyApp extends StatefulWidget {
    @override
    State&lt;StatefulWidget&gt; createState() {
      return MyAppState();
    }
  }
  
  class MyAppState extends State&lt;MyApp&gt; {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
          title: "Different Widgets",
          debugShowCheckedModeBanner: false,
          home: _showRadioButton());
    }
  
    List&lt;Widget&gt; makeRadios() {
      int _selected = 0;
  
      void onChanged(int value) {
        setState(() {
          _selected = value;
        });
      }
  
      List&lt;Widget&gt; list = List&lt;Widget&gt;();
  
      for (int i = 0; i &lt; 3; i++) {
        list.add(Row(
          children: &lt;Widget&gt;[
            Text("Radio"),
            Radio(
                value: i,
                groupValue: _selected,
                onChanged: (int value) {
                  onChanged(value);
                })
          ],
        ));
      }
  
      for (int i = 0; i &lt; 3; i++) {
        list.add(RadioListTile(
            value: i,
            groupValue: _selected,
            onChanged: (int value) {
              onChanged(value);
            },
          title: Text("title"),
        activeColor: Colors.red,
        secondary: Icon(Icons.access_alarm),
        subtitle: Text("Gender"),
        ));
      }
  
      return list;
    }
  
    Widget _showRadioButton() {
      return Scaffold(
        appBar: AppBar(
          title: Text("Hi"),
        ),
        body: Container(
          padding: EdgeInsets.all(10.0),
          child: Center(
            child: Column(
              children:
                makeRadios()
  
            ),
          ),
        ),
      );
    }
  </code></pre>
  
  <p>I don't get it why the onChanged of the radio button is not being called?
  The onChanged for TextField and checkbox is also not working.</p>