title: Java regex in String replaceAll: negative look ahead does not work as expected
body: <p>I am trying to process text and replace all the occurence that start with "www." with a certain word (in this cases "Banana"), but I want to exclude all the cases in which there is "http://" before the "www".</p>
  
  <p>When I use a positive lookahead it works (only the <a href="http://www" rel="nofollow noreferrer">http://www</a> case changes), but when I use a negative lookahead - both words change.</p>
  
  <p>Can you help me with this one?</p>
  
  <pre><code>String baseString = "replace this: www.q.com and not this:http://www.q.com";
  String positiveLookahead = baseString.replaceAll("(?:http://)www([^ \n\t]*)", "Banana");
  String negativeLookahead = baseString.replaceAll("(?!http://)www([^ \n\t]*)", "Banana");
  
  //positiveLookahead works (changes only the scond phrase), but positiveLookahead does not (changes both)
  </code></pre>