title: How to validated fields in an Xamarin/Android app
body: <p>Does any one know how to make a field required in Xamarin/Android app?</p>
  
  <p>I have this field and button in my Android Layout, and I'd like to make sure the info is entered before they go to the next activity.</p>
  
  <pre><code>&lt;TextView
      android:text="Zip Code:"
      android:textAppearance="?android:attr/textAppearanceMedium"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/zipCodeLabel"
      android:textColor="#000000"
      android:textSize="20sp" /&gt;
  &lt;Button
      android:id="@+id/btnSearch"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:text="@string/btnSearch"
      android:textSize="30sp" /&gt;
  </code></pre>
  
  <p>If found this for iOS, but can't find something similar for Android:
  <a href="https://developer.xamarin.com/recipes/ios/standard_controls/text_field/validate_input/" rel="nofollow">https://developer.xamarin.com/recipes/ios/standard_controls/text_field/validate_input/</a></p>