title: Modifying the return value of an abstract method during runtime
body: <p>Is it possible to modify the return value of an abstract method during runtime?</p>
  
  <p>For instance:</p>
  
  <pre><code>public abstract class Task {
      public abstract boolean validate();
  
      public void setValidate(boolean b) {
          /* modify the return value of 'validate' method */
      }
  }
  </code></pre>