title: how to refresh ListView.builder flutter
body: <p>How can I refresh my ListView.builder when adding item to the list?</p>
  
  <pre><code>ListView.builder(
        itemCount: propList.length,
        scrollDirection: Axis.horizontal,
        shrinkWrap: true,
        itemBuilder: (context,index)=&gt; Text(propList[index]),
      )
  </code></pre>
  
  <p>my button is</p>
  
  <pre><code>FlatButton(onPressed: (){propList.add('text');}, child: Text('add'))
  </code></pre>