title: Are enums allowed to have setters in Java?
body: <p>I have an <code>enum</code> and it has a parameter (field) that is a <code>String</code>.
  Am I allowed to have a setter for this field?</p>
  <pre><code>public enum Blah {
      Monday(&quot;a&quot;), Tuesday(&quot;b&quot;);
  }
  
  private final String letter;
  
  Blah(String letter){
      this.letter = letter;
  }
  </code></pre>
  <p>Am I allowed to do the following?</p>
  <pre><code>public String setLetter(String letter){
      this.letter = letter;
  }
  </code></pre>