title: Android cannot use support v7
body: <p>under Demo it shows <code>The hierarchy of the type Demo is inconsistent</code>,
  under RecyclerView it shows <code>The type android.support.v4.view.ScrollingView cannot be resolved</code>. It is indirectly referenced from required .class files.
  How do I resolve this?</p>
  
  <pre><code>public class Demo extends RecyclerView {
  
      public Demo(Context context, AttributeSet attrs) {
          super(context, attrs);
      }
  }
  </code></pre>