title: Why regular expression in Java cannot recognize \s as space character?
body: <p>I read from a lot of webpage (for example: <a href="http://www.wellho.net/regex/java.html" rel="nofollow noreferrer">http://www.wellho.net/regex/java.html</a>), they all mentioned that \s could represent any space charactor. But when I use \s in Java, it is not an eligible expression.</p>
  
  <p>Anyone know the reason? </p>