title: Android Studio EditText want a red line when field is empty and green when not empty
body: <p>Im trying to make my first app and trying to indicate when the field is empty or not while on run.. </p>
  
  <pre><code>&lt;EditText
      android:inputType="numberDecimal"
      android:id="@+id/elecCurrentEdit"
      android:layout_alignParentRight="true"
      android:layout_below="@id/electPriviousEdit"
      android:layout_width="120sp"
      android:layout_height="wrap_content" /&gt;
  </code></pre>