title: missing concrete implementation of state.build
body: <p>I am getting this error in Dart:
  &quot;Missing concrete implementation of &quot;state.build&quot;&quot;</p>
  <p>The first method is the following:</p>
  <pre><code>class MyHomePage extends StatefulWidget {
    // String titleInput;
    // String amountInput;
    @override
    MyHomePageState createState() =&gt; MyHomePageState();
  }
  
  class MyHomePageState extends State&lt;MyHomePage&gt; {
    final List&lt;Transaction&gt; _userTransactions = [
      // Transaction(
      //   id: &quot;t1&quot;,
      //   title: &quot;New Shoes&quot;,
      //   amount: 69.99,
      //   date: DateTime.now(),
      // ),
      // Transaction(
      //   id: &quot;t2&quot;,
      //   title: &quot;Weekly Groceries&quot;,
      //   amount: 16.53,
      //   date: DateTime.now(),
      // ),
    ];
  </code></pre>
  <p>Does anyone knows what this error means and how to solve it?</p>
  <p>Thank you.</p>