Important topics/APIs list for Java interview
<p>This is little different from what already been asked for <a href="http://stackoverflow.com/questions/706190/java-books-for-preparing-for-interviews">here</a>  </p>

<p>I would like to know what topics/APIs are most important for Java interviews. for example - </p>

<ul>
<li><strong>Concurrency</strong>,   </li>
<li><strong>Collections</strong><br>
.....and like that.  </li>
</ul>

<p>The reason is because implementations like <code>ConcurrentHashMap</code> (read <a href="http://www.ibm.com/developerworks/java/library/j-jtp08223/" rel="nofollow">here</a>) have so much details in them, that one would like to discuss about them as it covers many important aspects</p>
