title: adding view tag in xml shows the error: Unable to inflate view tag without class attribute
body: <p>A part of my <code>xml</code> you can see, the error is from <code>&lt;view/&gt;</code> tag. When I delete one of the view, it will be ok. I also have used it but it did not appear the error. So what is the reason of it?
  Thanks!</p>
  
  <pre><code>&lt;view
     android:layout_width="1dp"
     android:layout_height="match_parent"
     android:background="@color/colorPopul"&gt;
  &lt;/view&gt;
  </code></pre>