title: Trouble importing android.support.v7.widget.CardView into Eclipse
body: <p>I use Eclipse and I'm trying to create an application using the new <code>support-library-v7:21.+</code> from Lollipop.</p>
  
  <ul>
  <li>Created my new project</li>
  <li>imported in eclipse the <code>support-library-v7</code></li>
  <li>changed in <code>project-properties</code> of support library the line: <code>target=android-21</code> with 21 target</li>
  <li>changed the target of my application in 21</li>
  <li>imported the library in my project</li>
  <li>clean all</li>
  </ul>
  
  <p>After all i still got the invalid <code>R</code> declaration. I restarted Eclipse and then, after re-importing the library, seem went! I created a <code>Tolbar</code> and a <code>NavigationDrawer</code> as well without problem - it works.</p>
  
  <p>Now, i would like to put a <code>CardView</code> in my <code>ListView</code> items:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      xmlns:card_view="http://schemas.android.com/apk/res-auto"
     &gt;
      &lt;!-- A CardView that contains a TextView --&gt;
      &lt;android.support.v7.widget.CardView
          xmlns:card_view="http://schemas.android.com/apk/res-auto"
          android:id="@+id/card_view"
          android:layout_gravity="center"
          android:layout_width="200dp"
          android:layout_height="200dp"
          card_view:cardCornerRadius="4dp"&gt;
      &lt;TextView
          android:id="@+id/name"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          /&gt;
      &lt;TextView
          android:id="@+id/codename"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          /&gt;
      &lt;TextView
          android:id="@+id/versione"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          /&gt;
      &lt;TextView
          android:id="@+id/link"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          /&gt;
      &lt;TextView
          android:id="@+id/timestamp"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          /&gt;
  
      &lt;/android.support.v7.widget.CardView&gt;
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>well, first error: <code>No resource identifier found for attribute 'cardCornerRadius'</code>.
  I tried to delete the attribute, restart the application but I get a the following crash: </p>
  
  <pre><code>java.lang.RuntimeException: Binary XML file line #2: You must supply a layout_width attribute.
  </code></pre>
  
  <p>I don't understand what the problem is.</p>