title: Is it OK/possible to modify instance variables inside an enum declaration?
body: <p>Or, to re-phrase it: can enum types be "mutable"?</p>
  
  <pre><code>public enum Foo {
      ONE,TWO;
  
      private String bar;
  
      Foo() { this.bar = ""; }
      String bar() { return bar; }
  
      // legal?
      void bar(String bar) { this.bar = bar; }
  }
  </code></pre>
  
  <p>I guess if I want to modify it, it's no longer an enum type. </p>
  
  <p>Thoughts?</p>