title: The program is not executed - compilation warnings
body: <p>I am a new java programmer. I am trying to execute this program in eclipse but the error is </p>
  
  <pre><code>The serializable class LoveJava does not declare a static final serialVersionUID field of type long.
  </code></pre>
  
  <hr>
  
  <pre><code>private static final long serialVersionUID = 1L; 
  </code></pre>
  
  <p>Why I have to declare this line?</p>
  
  <pre><code>import acm.graphics.*;
  import acm.program.*;
  
  public class LoveJava extends GraphicsProgram {
  
      private static final long serialVersionUID = 1L;
  
      public void run(){
          add(new GLabel("I love Java"),100,75);
      }
  }
  </code></pre>