FULL PRODUCT VERSION :
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)

ALSO OCCURS ON

java version "1.6.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-beta-b59g)
Java HotSpot(TM) Client VM (build 1.6.0-beta-b59g, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
Upon removing the last component from a "java.awt.CardLayout" container the
componentShown(ComponentEvent e) method in the ComponentListener set on the component is INCORRECTLY invoked!

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run supplied test case:

java de.gaskin.bugs.CompEventBug1


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The method componentShown(...) should NOT be invoked when the last card is removed.
ACTUAL -
The method componentShown(...) is invoked and the source of the event is incorrectly set.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package de.gaskin.bugs;

import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Component;
import java.awt.Container;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JLabel;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;

class CompEventBug1 extends ComponentAdapter implements ActionListener {
   private final static String CARD1 = "CardOne";
   private final static String CARD2 = "CardTwo";
   private JPanel cardPane;
   private CardLayout cl;
   private JButton remove;
   private JTextArea protocol;
   CompEventBug1(JButton remove, JTextArea protocol) {
      this.remove = remove;
      this.protocol = protocol;
      CardLayout cl = new CardLayout();
      cardPane = new JPanel(cl);
// cardPane.addComponentListener(this);
      add(CARD1);
      add(CARD2);
   }
   private void add(String name) {
      JLabel label = new JLabel(name);
      label.setName(name);
      cardPane.add(label, name);
      label.addComponentListener(this);
   }
   public void actionPerformed(ActionEvent ae) {
      cardPane.remove(0);
      reportState();
   }
   public void componentShown(ComponentEvent e) {
      Component source = (Component)e.getSource();
      if (source.isShowing()) { // This is also the workaround
         protocol.append("'componentShown' invoked and is correct "
           + source.getName() + " is now showing\n");
      }
      else { // THIS IS THE BUG
         remove.setEnabled(false);
// System.out.println(source.getName() + " " + source.isShowing());
         protocol.append("============== AND HERE IS THE BUG ==========\n");
         protocol.append("'componentShown' invoked BUT SHOULD NOT HAVE BEEN\n");
         protocol.append(" e.getSource() is " + source.getName() + "\n");
         protocol.append(" e.isShowing() is " + source.isShowing()+ "\n");
         
      }
   }
   private void reportState() {
      int nbrCards = cardPane.getComponents().length;
      protocol.append("CardPane has " + nbrCards + " cards\n");
      if (nbrCards > 0) {
         protocol.append("\nPlease Click 'remove'\n");
      }

   }
   public static void main(String[] args) {
      JFrame frame = new JFrame("ComponentEvent Bug");
      JButton remove = new JButton("Remove a Card");
      JTextArea protocol = new JTextArea(10, 80);
      CompEventBug1 ceb1 = new CompEventBug1(remove, protocol);
      Container contentPane = frame.getContentPane();
      remove.addActionListener(ceb1);
      contentPane.add(ceb1.cardPane, BorderLayout.NORTH);
      contentPane.add(remove, BorderLayout.CENTER);
      contentPane.add(new JScrollPane(protocol), BorderLayout.SOUTH);
      frame.pack();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
      ceb1.reportState();
   }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
   public void componentShown(ComponentEvent e) {
      Component source = (Component)e.getSource();
      if (source.isShowing()) { // This is the workaround
         .....
     }
}