title: Flutter: Dropdownbutton does not update to display selected choice
body: <p>I am trying to use a dropdown button to have the user select from a list of options, however after making a selection the dropdown button remains displaying the hint. I think something about the setState is not updating the dropdown button.</p>
  
  <pre><code>              value: skillChoice,
                items: listDrop,
                hint: Text("Choose Skill"),
                onChanged: (value) {
  
                  setState(() {
                    skillChoice = value;
                  });
                },
              ),
  </code></pre>
  
  <p>here are the variables which are declared earlier in the code:</p>
  
  <pre><code>      List&lt;DropdownMenuItem&lt;int&gt;&gt; listDrop = [];
        int skillChoice = null;
  </code></pre>
  
  <p>Can anyone let me know why it isn't updating?</p>