code: public static String getSuffix (final String string, final String prefix) {
          if (string == null || prefix == null || prefix.length() > string.length()) return null;
          final String stringPrefix = string.substring(0, prefix.length());
          if (stringPrefix.equals(prefix)) return string.substring(prefix.length());
          return null;
      }
docs: Returns the suffix of a specified {@link String}. The length of the suffix is equal to the length of
  <i>string</i> minus the lenght of <i>prefix</i>, but of course only if the beginning of <i>string</i> does equal
  <i>prefix<i>. If <i>prefix</i> is not a prefix of <i>string</i>, <code>null</code> is returned.
  
  @param string the {@link String} whose suffix we want to have returned
  @param prefix a prefix of <i>string</i>
  @return the suffix or <code>null</code>