title: How to check if an object implements an interface?
body: <p>How to check if some class implements interface? 
  When having: </p>
  
  <p><code>Character.Gorgon gor = new Character.Gorgon();</code> </p>
  
  <p>how to check if <code>gor</code> implements <code>Monster</code> interface?</p>
  
  <pre><code>public interface Monster {
  
      public int getLevel();
  
      public int level = 1;
  }
  
  public class Character {
      public static class Gorgon extends Character implements Monster {
          public int level;
          @Override
          public int getLevel() { return level; }
  
          public Gorgon() {
              type = "Gorgon";
          }
      }
  }
  </code></pre>
  
  <hr>
  
  <p>Is the method <code>getLevel()</code> overridden in <code>Gorgon</code> correctly, so it can return <code>level</code> of new <code>gor</code> created?</p>