title: Grouping classes with an interface in Java
body: <p>I have 40 classes of tags that extend from 4 super classes. I would like to categorize each of these 40 classes to either a technical tag or a user tag. </p>
  
  <p>I am only interested in technical tags. Would it be good design to make an interface <code>TechnicalTag</code> that has no methods inside it and implement it in say each of that class that I want to be a technical tag so that I can use <code>instanceOf</code> to pick them? </p>
  
  <p>The reason I do not want a method <code>isTechnicalTag</code> that returns a <code>boolean</code> is because that would mean I will have to implement them in all the 40 classes. And the technical tag for now is perhaps only 4 of them. </p>
  
  <p>Kindly advise me. OOP is not exactly what I am trained on.</p>