title: Dummy implementation design pattern name
body: <p>To avoid NullPointerExceptions I find it useful to provide an immutable dummy implementation of an interface together with the interface. Like this:</p>
  
  <pre><code>public interface Action {
  
    void perform();
  
    public static final Action dummy = new Action() {
      public void perform() { 
        /*nothing*/ 
      }
    };
  
  }
  </code></pre>
  
  <p><code>Action.dummy</code> can then be used instead of the evil <code>null</code>. </p>
  
  <p>Is there a name for this design pattern?</p>