title: Superclass and subclass each with it's own interface
body: <p>Is the following ok? (keep in mind that I didn't write the bodies of the classes and I also didn't write the interfaces ;-))</p>
  
  <pre><code>abstract class SuperClass implements SuperInterface
  
  class SubClass extends SuperClass implements SubInterface
  </code></pre>
  
  <p>Or is this generally considered bad practice?</p>
  
  <p>What made me wonder is, that the following didn't work:</p>
  
  <pre><code>List&lt;SubInterface&gt; myList;
  ...
  for(SuperInterface si : myList) {
      ...
  }
  </code></pre>