title: Is it safe to get values from a java.util.HashMap from multiple threads (no modification)?
body: <p>There is a case where a map will be constructed, and once it is initialized, it will never be modified again.  It will however, be accessed (via get(key) only) from multiple threads.  Is it safe to use a <code>java.util.HashMap</code> in this way?</p>
  
  <p>(Currently, I'm happily using a <code>java.util.concurrent.ConcurrentHashMap</code>, and have no measured need to improve performance, but am simply curious if a simple <code>HashMap</code> would suffice.  Hence, this question is <em>not</em> "Which one should I use?" nor is it a performance question.  Rather, the question is "Would it be safe?")</p>