title: Java Built-in Observer pattern
body: <p>Regarding the observer built-in design pattern:</p>
  
  <pre><code> java.util.Observable;
   java.util.Observer;
  </code></pre>
  
  <p>Does thet observation have to be serializable?</p>
  
  <p>The <code>Observer</code> has a contract to implement an <code>update</code> method for callbacks on what its observing. The callback would look like this:</p>
  
  <pre><code>@Override
  public void update(Observable observable, final Object observation) {
      // do some stuff with the notification
  }
  </code></pre>
  
  <p>My question then is: the last parameter called observation, does it have to be serializable or can I notify on any kind of object?</p>