title: what's different @android:id/list @+id/android:list?
body: <p>i see two listview xml code:</p>
  
  <pre><code>&lt;ListView
      android:id="@android:id/list"
  ...
  </code></pre>
  
  <p>and</p>
  
  <pre><code>&lt;ListView
      android:id="@+id/android:list"
  </code></pre>
  
  <p>whats different between those?</p>