title: Setting scrollbars property in RecyclerView crashes my app
body: <p>I recently started using RecyclerView replacing older ListView. But whenever I use <code>android:scrollbars="vertical"</code> in <code>android.support.v7.widget.RecyclerView</code> element, my app crashes with the following error: 
  <code>Attempt to invoke virtual method 'boolean android.support.v7.widget.RecyclerView$LayoutManager.canScrollVertically()' on a null object reference</code></p>
  
  <p>This is how I'm using RecyclerView:</p>
  
  <pre><code>View rootView;
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      rootView = inflater.inflate(R.layout.my_fragment, container, false);
      return rootView;
  }
  protected void onPostExecute(Boolean result) {
      RecyclerView rv = (RecyclerView) rootView.findViewById(R.id.recyclerview);
      LinearLayoutManager llm = new LinearLayoutManager(context);
      rv.setLayoutManager(llm);
      RecycleViewAdapter adapter = new RecycleViewAdapter(myRecyclerViewAdapter);
      rv.setHasFixedSize(true);
      rv.setAdapter(adapter);
  }
  </code></pre>
  
  <p>And this is <code>my_fragment.xml</code> file:</p>
  
  <pre><code>&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:orientation="vertical"&gt;
  
      &lt;android.support.v7.widget.RecyclerView
          android:id="@+id/recyclerview"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:scrollbars="vertical"&gt;
  
      &lt;/android.support.v7.widget.RecyclerView&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>Everything works perfectly fine if I don't use <code>android:scrollbars="vertical"</code>. Thanks for your help.</p>