public String get(int groupId) {
        if (groups == null) {
            return null;
        }
        return groups[groupId];
    }
Object contains regex results.<br>
For multi group result extension.<br>

@author code4crafter@gmail.com <br>
@since 0.1.0
webmagic-core/src/main/java/us/codecraft/webmagic/selector/RegexResult.java