title: Append items dynamically to ListView
body: <p>I am new to Dart and Flutter and try to append a new item to my ListView. I created a button that increments <code>this.value</code> but nothing happens. Am I missing an update call on the UI and is this even the correct approach?
  Since I return the value of <code>ListView.builder</code> directly to the caller of <code>build</code> I am not sure how to get the list to add more items. Thanks a lot!</p>
  
  <pre><code>class MyList extends State&lt;MyList&gt; {
  
  ... 
  int value = 2;
  
  @override
  Widget build(BuildContext context) {
  return ListView.builder(
      itemCount: this.value,
      itemBuilder: (context, index) =&gt; this._buildRow(index)
  );
  </code></pre>
  
  <p><strong>TL;DR:</strong> Is calling <code>setState</code> the correct way to trigger an UI update?</p>