title: Is this Singleton a thread safe one ? I can't see how?
body: <p>Consider the Singleton : </p>
  
  <pre><code>public final class MySingleton {
      private static class Nested 
      {
          private static final MySingleton INSTANCE = new MySingleton();
      }
  
      private MySingleton() 
      {
          if (Nested.INSTANCE != null) 
          {
              throw new IllegalStateException("Already instantiated");
          }
      }
  
      public static MySingleton getInstance() 
      {
          return Nested.INSTANCE;
      }
  }
  </code></pre>
  
  <p>I didn't put any locks , but why is this a thread safe solution for the Singleton problem ? </p>