title: How thread-safe is enum in java?
body: <p>How thread-safe is enum in java?
  I am implementing a Singleton using enum (as per Bloch's Effective Java),
  should I worry at all about thread safety for my singleton enum?
  Is there a way to prove or disprove that it is thread safe?</p>
  
  <pre><code>// Enum singleton - the preferred approach
  public enum Elvis { 
      INSTANCE;
      public void leaveTheBuilding() { ... }
  }
  </code></pre>
  
  <p>Thanks</p>