7)
        at java.util.regex.Pattern.compile(Pattern.java:1022)
        at RegexExample.main(RegexExample.java:13)
</pre>

        <p>Good programming style dictates that the user should not see a
        stack trace, even if the user supplies invalid output.</p>
      </div>

      <div id="run1">
        <h4>3. Run the Regex Checker</h4>

        <p>The Regex Checker prevents, at compile time, use of
        syntactically invalid regular expressions and access of invalid
        capturing groups. In othe