title: What do these special characters mean in Java?
body: <p>I was looking at some of the jdk code. I found these characters. Could someone explain to me what do these mean.</p>
  
  <pre><code>public static String quote(String s) {
      int slashEIndex = s.indexOf("\\E");        // What does this mean. Is this a special char in java. if so what does this do.
      if (slashEIndex == -1)
          return "\\Q" + s + "\\E";          
  
      StringBuilder sb = new StringBuilder(s.length() * 2);
      sb.append("\\Q");
      slashEIndex = 0;
      int current = 0;
      while ((slashEIndex = s.indexOf("\\E", current)) != -1) {
          sb.append(s.substring(current, slashEIndex));
          current = slashEIndex + 2;
          sb.append("\\E\\\\E\\Q");
      }
      sb.append(s.substring(current, s.length()));
      sb.append("\\E");
      return sb.toString();
  }
  </code></pre>
  
  <p>From the above code example I was able to figure out what's happening as in the method finds the occurrences of \ and converts them to \E and \Q. Could someone explain why that's the case. </p>
  
  <p>For more context on this method, I was looking into the Pattern.quote() method from jdk 1.6</p>