title: Box2D/AndEngine - ContactListener for multiple object classes
body: <p>I'm developing a little Android game in Java, using AndEngine for graphics and Box2D for physics - specifically, collision handling. I have some different types of objects with constructors in classes, like so:</p>
  
  <pre><code>MainActivity.java
  Enemy.java
  Npc.java
  Door.java
  </code></pre>
  
  <p>I have a static PhysicsWorld in the main class, and I was setting up a ContactListener from the Enemy class, to define what happens when one of the enemies hits something. However, I tried to set up another ContactListener for the Door class, when I discovered that each PhysicsWorld has only one ContactListener.</p>
  
  <p>Essentially, my question is this: what is the best way to get around this?</p>
  
  <p>I'm aware I've probably explained this rather badly, so my apologies.</p>