Why is StringBuilder final - versus having all final methods?
<p>The motivation for this was my answer ("Wishful thinking") to an <a href="http://stackoverflow.com/questions/7446994/what-are-the-pros-and-cons-of-having-private-methods-return-string-instead-of-pas/7447512#7447512">earlier question on StringBuilder best-practices</a>.  If StringBuilder was extensible, then domain-specific subclasses could extend its fluent interface, which would tighten up code where a StringBuilder gets passed around to a lot of methods that build parts of a larger string.  </p>

<p>I'm considering suggesting something - maybe a StringBuilder delegate -  to the Guava folks.</p>

<p>What additional purpose does it serve for StringBuilder to be final, as opposed to just having final methods?</p>
