title: When to implement Comparable<super class of X> instead of Comparable<X>?
body: <pre><code>class A { ... }
  
  
  class B extends A implements Comparable&lt;A&gt; {
      int compareTo(A aobject) { ... }
  }
  </code></pre>
  
  <p>Usually we implement <code>Comparable</code> with a type-parameter of <code>B</code>. But java allows using a super class, as well. </p>
  
  <p>Is there a scenario where I really need to do something like this?</p>