title: Is there some special meaning to the text "<? >"?
body: <pre><code>private final Class&lt;? extends FragmentActivity&gt; activityClass;
  </code></pre>
  
  <p>I understand the definition except for the <code>&lt;? &gt;</code> part.</p>
  
  <p>Is there some reason for the extends to be enclosed in that special text?</p>