Java AWT CardLayout control by JComboBox

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main {
   public static void main(String[] args) {
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setTitle("CardLayout frame");
      /*from www .  j  a  v a 2s .  c o  m*/
      
      JPanel cardPanel = new JPanel();
      cardPanel.setLayout(new CardLayout());
      cardPanel.setPreferredSize(new Dimension(300, 400));
      
      JPanel bluePanel = new JPanel();
      JPanel redPanel = new JPanel();
      bluePanel.setBackground(Color.blue);
      redPanel.setBackground(Color.red);
      
      cardPanel.add(bluePanel, "BLUE PANEL");
      cardPanel.add(redPanel, "RED PANEL");
      
      JPanel comboBoxPanel = new JPanel();
      String comboBoxItems[] = { "BLUE PANEL", "RED PANEL" };
      JComboBox<String> cb = new JComboBox<>(comboBoxItems);
      cb.setEditable(false);
      cb.addItemListener(new ItemListener(){
         @Override
         public void itemStateChanged(ItemEvent evt) {
            CardLayout cl = (CardLayout)(cardPanel.getLayout());
            cl.show(cardPanel, (String)evt.getItem());
         }
      });
      comboBoxPanel.add(cb);
      
      frame.getContentPane().add(comboBoxPanel, BorderLayout.PAGE_START);
      frame.getContentPane().add(cardPanel, BorderLayout.CENTER);
      
      frame.pack();
      frame.setVisible(true);
   }
}