title: When saving a Serializable object, does everything referenced need to be Serializable too?
body: <p>This may be obvious, but I'm not quite getting my head around Serialization:</p>
  
  <p>I have a single object which holds the state of my application. This object references multiple other objects.</p>
  
  <p>eg</p>
  
  <pre><code>ApplicationState implements Serializable
      private ArrayList&lt;SomeApplicationObjects&gt;
      private AnApplicationObject
      private AnotherObject
  </code></pre>
  
  <p>All of these objects (someApplicationObjects, anApplicationObject, anotherObject) need to be serializable, as far as I understand.</p>
  
  <p>But do objects THEY reference also need to be serializable? eg does SubObject here need to be serializable too? Does this essentially mean that every sub-object needs to be Serializable, recursively, from the ApplicationState down?</p>
  
  <pre><code>AnotherObject implements Serializable
      private SubObject
  </code></pre>