v

Name: clC74495 Date: 10/06/99


Carlos.Lucasius@Canada (October 6, 1999): regression of bug 4110285?

/***************************************************************************

JMenuBars are damaged by serialization (they can't be serialized twice)

JMenuBars are damaged when they are serialized, such that they can't be
serialized twice in a row. This sample program can be used to
demonstrate the problem; it opens a window with a simple JMenuBar and
a button marked "Serialize".

Run the program and push the "Serialize" button; it seems to be work. But
look closely at the JMenuBar; the border is now missing! It looks like
the border was not properly re-installed at the end of the normal
serialization kludge.

Now press the "Serialize" button again; this time you get a
NullPointerException.

This bug is pretty important if you are building an IDE that supports
visual editing of menus.

This problem happens with this build (but it's been broken for years):

  java version "1.3.0"
  Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-G)
  Java HotSpot(TM) Client VM (build 1.3-G, mixed mode)


This bug can be easily fixed in JMenuBar.java by adding this block of
code to the writeObject method, just after the call to s.defaultWriteObject():

        if ((ui != null) && (getUIClassID().equals(uiClassID)))
        {
            ui.installUI(this);
        }

Here is the output from the sample program:

Serializing...
Serialization complete.
Serializing...
Exception occurred during event dispatching:
java.lang.NullPointerException
        at javax.swing.LookAndFeel.uninstallBorder(LookAndFeel.java:123)
        at javax.swing.plaf.basic.BasicMenuBarUI.uninstallDefaults(BasicMenuBarUI.java:143)
        at javax.swing.plaf.basic.BasicMenuBarUI.uninstallUI(BasicMenuBarUI.java:135)
        at javax.swing.JComponent.compWriteObjectNotify(JComponent.java:4428)
        at javax.swing.JComponent$EnableSerializationFocusListener.writeObject(JComponent.java:4418)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1811)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1186)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:362)
        at java.awt.AWTEventMulticaster.save(AWTEventMulticaster.java:767)
        at java.awt.Component.writeObject(Component.java:4463)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1811)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1186)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:362)
        at java.io.ObjectOutputStream.outputArray(ObjectOutputStream.java:1074)
        at java.io.ObjectOutputStream.checkSubstitutableSpecialClasses(ObjectOutputStream.java:452)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:357)
        at java.io.ObjectOutputStream.outputClassFields(ObjectOutputStream.java:1774)
        at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:473)
        at java.awt.Container.writeObject(Container.java:1859)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1811)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1186)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:362)
        at java.io.ObjectOutputStream.outputArray(ObjectOutputStream.java:1074)
        at java.io.ObjectOutputStream.checkSubstitutableSpecialClasses(ObjectOutputStream.java:452)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:357)
        at java.io.ObjectOutputStream.outputClassFields(ObjectOutputStream.java:1774)
        at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:473)
        at java.awt.Container.writeObject(Container.java:1859)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1811)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1186)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:362)
        at java.io.ObjectOutputStream.outputArray(ObjectOutputStream.java:1074)
        at java.io.ObjectOutputStream.checkSubstitutableSpecialClasses(ObjectOutputStream.java:452)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:357)
        at java.io.ObjectOutputStream.outputClassFields(ObjectOutputStream.java:1774)
        at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:473)
        at java.awt.Container.writeObject(Container.java:1859)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.io.ObjectOutputStream.invokeObjectWriter(ObjectOutputStream.java:1811)
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1186)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:362)
        at MenuBarTest.actionPerformed(MenuBarTest.java:147)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1244)
        at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1296)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:378)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:250)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:238)
        at java.awt.Component.processMouseEvent(Component.java:3677)
        at java.awt.Component.processEvent(Component.java:3506)
        at java.awt.Container.processEvent(Container.java:1255)
        at java.awt.Component.dispatchEventImpl(Component.java:2563)
        at java.awt.Container.dispatchEventImpl(Container.java:1304)
        at java.awt.Component.dispatchEvent(Component.java:2466)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:2550)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:2315)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:2218)
        at java.awt.Container.dispatchEventImpl(Container.java:1291)
        at java.awt.Window.dispatchEventImpl(Window.java:872)
        at java.awt.Component.dispatchEvent(Component.java:2466)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:322)
        at java.awt.EventDispatchThread.pumpOneEvent(EventDispatchThread.java:107)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:97)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:88)
*****************************************************************************/

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;

public class MenuBarTest implements ActionListener
{
    public static void main(String args[])
    {
        new MenuBarTest();
    }

    JFrame jf1;
    JButton jb1;
    JMenuBar mb;
    JMenuItem mi;
    JMenu m;

    public MenuBarTest()
    {
        jf1 = new JFrame("Test JMenuBar Serialization");
        jb1 = new JButton("Serialize");
    
        jf1.setSize(300,100);
        jf1.getContentPane().setLayout(new FlowLayout());
        jf1.getContentPane().add(jb1);
                                
        mb = new JMenuBar();
            m = new JMenu("Menu",true);
                mi = new JMenuItem("MenuItem");
                m.add(mi);
        mb.add(m);

        jf1.setJMenuBar(mb);

        jb1.addActionListener(this);
        jf1.show();
    }

    public void actionPerformed(ActionEvent e)
    {
        if (e.getSource() == jb1)
        {
            System.out.println("Serializing...");
            try
            {
                FileOutputStream ostream;
                ObjectOutputStream p;
                ostream = new FileOutputStream("test.out");
                p = new ObjectOutputStream(ostream);

                p.writeObject(jf1);
                p.flush();
                ostream.close();
            }
            catch (IOException ie)
            {
                ie.printStackTrace();
                System.exit(0);
            }
            System.out.println("Serialization complete.");
        }
    }
}
(Review ID: 96110)
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