title: replaceAll "/" with File.separator
body: <p>In Java, when I do:</p>
  
  <pre><code>    "a/b/c/d".replaceAll("/", "@");
  </code></pre>
  
  <p>I get back</p>
  
  <pre><code>    a@b@c@d
  </code></pre>
  
  <p>But when I do:</p>
  
  <pre><code>    "a/b/c/d".replaceAll("/", File.separator);
  </code></pre>
  
  <p>It throws a StringIndexOutOfBoundsException, and I don't know why. I tried looking this up, but it wasn't very helpful.  Can anyone help me out?</p>