title: What does it mean: The serializable class does not declare a static final serialVersionUID field?
body: <p>I have the warning message given in the title. I would like to understand and remove it. I found already some answers on this question but I do not understand these answers because of an overload with technical terms. Is it possible to explain this issue with simple words?</p>
  
  <p>P.S. I know what OOP is. I know what is object, class, method, field and instantiation.</p>
  
  <p>P.P.S. If somebody needs my code it is here:</p>
  
  <pre><code>import java.awt.*;
  import javax.swing.*;
  
  
  public class HelloWorldSwing extends JFrame {
  
          JTextArea m_resultArea = new JTextArea(6, 30);
  
          //====================================================== constructor
          public HelloWorldSwing() {
              //... Set initial text, scrolling, and border.
              m_resultArea.setText("Enter more text to see scrollbars");
              JScrollPane scrollingArea = new JScrollPane(m_resultArea);
              scrollingArea.setBorder(BorderFactory.createEmptyBorder(10,5,10,5));
  
              // Get the content pane, set layout, add to center
              Container content = this.getContentPane();
              content.setLayout(new BorderLayout());
              content.add(scrollingArea, BorderLayout.CENTER);
              this.pack();
          }
  
          public static void createAndViewJFrame() {
              JFrame win = new HelloWorldSwing();
              win.setTitle("TextAreaDemo");
              win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
              win.setVisible(true);
          }
  
          //============================================================= main
          public static void main(String[] args) {
              SwingUtilities.invokeLater(new Runnable(){
                  public void run(){
                      createAndViewJFrame();
                  }
              });
          }
  
  }
  </code></pre>