title: Fetch state/variable of other Stateful widgets
body: <p>I want to fetch the variable of other Stateful Widget</p>
  <p>For example, I have three widget such as <code>SmartTag</code>, <code>MySlider</code>, <code>MyHomePage</code></p>
  <p><code>MyHomePage</code> has <code>SmartTag</code> and <code>MySlider</code></p>
  <p>(this code is not correct just the bulky image)</p>
  <pre><code>class _SmartTagState extends State&lt;_SmartTagState&gt;{
      var tagState;
  
  class _MySliderState extends State&lt;_MySliderState&gt;{
      var sliderState;
  
  class MyHomePage extends StatefulWidget {}
  class _MyHomePageState extends State&lt;MyHomePage&gt; {
      return Row(
          children:[
          MySlider(),
          SmartTag()
          floatingActionButton: FloatingActionButton(
              onPressed: (){
                  print(MySlider.sliderState)//  I want to get the variable fron another widget.
                  print(SmartTag.tagState)//  I want to get the variable fron another widget.
              },
              tooltip: 'Increment',
              child: const Icon(Icons.add),
          ), 
      ]
      )
  }
  </code></pre>
  <p>What I want to do is, getting the other widget varliables when button is pushed.</p>
  <p>So,I have some quesitons.</p>
  <ol>
  <li>Is there any way to get the other widgets(<code>SmartTag</code>,<code>MySlider</code>) variable from  <code>_MyHomePageState</code>?</li>
  <li><code>_MyHomePageState</code> should have the all variables from the beginning? (However when code is long and comples, it's not useful)</li>
  </ol>
  <p>Any help appreciated thank you .</p>