title: Is a good practice to a class implements two or more interfaces?
body: <p>I saw this approach recently and I can't get out of my head that this is <strong>not</strong> a good practice. Some of the reasons for that:</p>
  
  <ol>
  <li><p>dependency, if you add a new method in your interface all the others classes have to implement it;</p></li>
  <li><p>memory usage, (I'm not sure here) When instance it a object from this class the memory usage will be higher than if you just have an association relation; </p></li>
  </ol>
  
  <p>I think that some languages don't allow this kind of <em>feature</em> for a reason but with Java I'm not so sure about it. Can anyone explain why we should implement multiple interfaces in a class or why we shouldn't ?</p>
  
  <p>Thank you!</p>