title: Can Boolean.valueOf(String) return null?
body: <p>Can <code>Boolean.valueOf(String)</code> ever return null? From what I can see in the java <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Boolean.html#valueOf%28java.lang.String%29">docs</a>, the docs only specify when it returns true. Is false always returned otherwise, or can null be returned? I have not been able to get it to return null in the tests I have done, but I would like to be sure.</p>
  
  <p>Essentially, I want to know if the following code is safe from a NullPointerException:</p>
  
  <pre><code>boolean b = Boolean.valueOf(...); 
  </code></pre>