title: How to show custom warning when FutureBuilder snapshot data equals to 0 (zero)?
body: <p>In my Flutter app body section I use FutureBuilder. If snapshot.hasData then I show the Data in body. My problem is that sometimes the snapshot data is 0 (zero). I need to use stack or similar to show user a warning with stating that “currently data is not available”. How do I do that?</p>
  
  <pre><code>body: new Center(
    child: new FutureBuilder(
        future: getCurrencyJsonData(),
        builder: (context, snaphot) {
          if (snaphot.hasData) {
            return new ListView(
  </code></pre>