title: Error: Only static members can be accessed in initializers what does this mean?
body: <p>I have something like this. I am having difficulty understanding this error.
  Why does accessing <code>filterController</code> here give this error here, but it doesn't give this error if I move the current entire <code>TextFormField</code> creation (between comments A and B) inside the build method? How does moving the entire <code>TextFormField</code> inside the build method make <code>filterController</code> static then and resolve this issue?</p>
  <pre><code>class AppHomeState extends State&lt;AppHome&gt; with SingleTickerProviderStateMixin
  {
  
      TabController _tabController;
      final filterController = new TextEditingController(text: &quot;Search&quot;);
          //----A
          TextFormField email = new TextFormField(
          keyboardType: TextInputType.emailAddress,
          controller: filterController,    ------&gt;ERROR : Error: Only static members can be accessed in initializers
          );
         //----B
  
    @override
      Widget build(BuildContext context)
      {
          return new Scaffold(
                  appBar: new AppBar(..),
          );
      }
  }
  </code></pre>
  <p>How can I resolve this issue?</p>