title: Practical side of the ability to define a class within an interface in Java?
body: <p>What would be the practical side of the ability to define a class within an interface in Java:    </p>
  
  <pre><code>interface IFoo
  {
      class Bar
      {
          void foobar ()
          {
              System.out.println("foobaring...");
          }
      }
  }
  </code></pre>