title: Use of Functional Interface in Java 8
body: <p>This is a follow up question from <a href="https://stackoverflow.com/questions/20001427/double-colon-operator-in-java-8">:: (double colon) operator in Java 8</a> in which Java allows you to refer to methods using <code>::</code> operator. </p>
  
  <p>Is it possible to provide some custom Functional Interface that I create and use it with <code>::</code> operator? And how to do it?  </p>