/*
 * @(#)JMenuItem.java	1.118 04/03/05
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package javax.swing;

import java.util.EventListener;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import java.io.Serializable;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.io.IOException;

import javax.swing.plaf.*;
import javax.swing.plaf.basic.*;
import javax.swing.event.*;
import javax.accessibility.*;

/**
 * An implementation of an item in a menu. A menu item is essentially a button
 * sitting in a list. When the user selects the "button", the action
 * associated with the menu item is performed. A <code>JMenuItem</code>
 * contained in a <code>JPopupMenu</code> performs exactly that function.
 * <p>
 * For further documentation and for examples, see
 * <a
 href="http://java.sun.com/docs/books/tutorial/uiswing/components/menu.html">How to Use Menus</a>
 * in <em>The Java Tutorial.</em>
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans<sup><font size="-2">TM</font></sup>
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @beaninfo
 *   attribute: isContainer false
 * description: An item which can be selected in a menu.
 *
 * @version 1.118 03/05/04
 * @author Georges Saab
 * @author David Karlton
 * @see JPopupMenu
 * @see JMenu
 * @see JCheckBoxMenuItem
 * @see JRadioButtonMenuItem
 */
public class JMenuItem extends AbstractButton implements Accessible,MenuElement  {

    /**
     * @see #getUIClassID
     * @see #readObject
     */
    private static final String uiClassID = "MenuItemUI";

    /* diagnostic aids -- should be false for production builds. */
    private static final boolean TRACE =   false; // trace creates and disposes
    private static final boolean VERBOSE = false; // show reuse hits/misses
    private static final boolean DEBUG =   false;  // show bad params, misc.

    private boolean isMouseDragged = false;

    /**
     * Creates a <code>JMenuItem</code> with no set text or icon.
     */
    public JMenuItem() {
        this(null, (Icon)null);
    }

    /**
     * Creates a <code>JMenuItem</code> with the specified icon.
     *
     * @param icon the icon of the <code>JMenuItem</code>
     */
    public JMenuItem(Icon icon) {
        this(null, icon);
    }

    /**
     * Creates a <code>JMenuItem</code> with the specified text.
     *
     * @param text the text of the <code>JMenuItem</code>
     */
    public JMenuItem(String text) {
        this(text, (Icon)null);
    }
    
    /**
     * Creates a menu item whose properties are taken from the 
     * specified <code>Action</code>.
     *
     * @param a the action of the <code>JMenuItem</code>
     * @since 1.3
     */
    public JMenuItem(Action a) {
        this();
	setAction(a);
    }

    /**
     * Creates a <code>JMenuItem</code> with the specified text and icon.
     *
     * @param text the text of the <code>JMenuItem</code>
     * @param icon the icon of the <code>JMenuItem</code>
     */
    public JMenuItem(String text, Icon icon) {
        setModel(new DefaultButtonModel());
        init(text, icon);
        initFocusability();
    }

    /**
     * Creates a <code>JMenuItem</code> with the specified text and
     * keyboard mnemonic.
     *
     * @param text the text of the <code>JMenuItem</code>
     * @param mnemonic the keyboard mnemonic for the <code>JMenuItem</code>
     */
    public JMenuItem(String text, int mnemonic) {
        setModel(new DefaultButtonModel());
        init(text, null);
        setMnemonic(mnemonic);
        initFocusability();
    }

    /**
     * Inititalizes the focusability of the the <code>JMenuItem</code>.
     * <code>JMenuItem</code>'s are focusable, but subclasses may
     * want to be, this provides them the opportunity to override this
     * and invoke something else, or nothing at all. Refer to
     * {@link javax.swing.JMenu#initFocusability} for the motivation of
     * this.
     */
    void initFocusability() {
	setFocusable(false);
    }

    /**
     * Initializes the menu item with the specified text and icon.
     *
     * @param text the text of the <code>JMenuItem</code>
     * @param icon the icon of the <code>JMenuItem</code>
     */
    protected void init(String text, Icon icon) {
        if(text != null) {
            setText(text);
        }
        
        if(icon != null) {
            setIcon(icon);
        }
        
        // Listen for Focus events
        addFocusListener(new MenuItemFocusListener());
        setUIProperty("borderPainted", Boolean.FALSE);
        setFocusPainted(false);
        setHorizontalTextPosition(JButton.TRAILING);
        setHorizontalAlignment(JButton.LEADING);
	updateUI();
    }

    private static class MenuItemFocusListener implements FocusListener,
        Serializable {
        public void focusGained(FocusEvent event) {}
        public void focusLost(FocusEvent event) {
            // When focus is lost, repaint if 
            // the focus information is painted
            JMenuItem mi = (JMenuItem)event.getSource();
            if(mi.isFocusPainted()) {
                mi.repaint();
            }
        }
    }
        
    
    /**
     * Sets the look and feel object that renders this component.
     *
     * @param ui  the <code>JMenuItemUI</code> L&F object
     * @see UIDefaults#getUI
     * @beaninfo
     *        bound: true
     *       hidden: true
     *    attribute: visualUpdate true
     *  description: The UI object that implements the Component's LookAndFeel. 
     */
    public void setUI(MenuItemUI ui) {
        super.setUI(ui);
    }
    
    /**
     * Resets the UI property with a value from the current look and feel.
     *
     * @see JComponent#updateUI
     */
    public void updateUI() {
        setUI((MenuItemUI)UIManager.getUI(this));
    }


    /**
     * Returns the suffix used to construct the name of the L&F class used to
     * render this component.
     *
     * @return the string "MenuItemUI"
     * @see JComponent#getUIClassID
     * @see UIDefaults#getUI
     */
    public String getUIClassID() {
        return uiClassID;
    }


    /**
     * Identifies the menu item as "armed". If the mouse button is
     * released while it is over this item, the menu's action event
     * will fire. If the mouse button is released elsewhere, the
     * event will not fire and the menu item will be disarmed.
     * 
     * @param b true to arm the menu item so it can be selected
     * @beaninfo
     *    description: Mouse release will fire an action event
     *         hidden: true
     */
    public void setArmed(boolean b) {
        ButtonModel model = (ButtonModel) getModel();

        boolean oldValue = model.isArmed();
        if(model.isArmed() != b) {
            model.setArmed(b);
        }
    }

    /**
     * Returns whether the menu item is "armed".
     * 
     * @return true if the menu item is armed, and it can be selected
     * @see #setArmed
     */
    public boolean isArmed() {
        ButtonModel model = (ButtonModel) getModel();
        return model.isArmed();
    }

    /**
     * Enables or disables the menu item.
     *
     * @param b  true to enable the item
     * @beaninfo
     *    description: Does the component react to user interaction
     *          bound: true
     *      preferred: true
     */
    public void setEnabled(boolean b) {
        // Make sure we aren't armed!
        if (b == false)
            setArmed(false);
        super.setEnabled(b);
    }


    /**
     * Returns true since <code>Menu</code>s, by definition, 
     * should always be on top of all other windows.  If the menu is
     * in an internal frame false is returned due to the rollover effect
     * for windows laf where the menu is not always on top.
     */
    // package private
    boolean alwaysOnTop() {
        // Fix for bug #4482165
        if (SwingUtilities.getAncestorOfClass(JInternalFrame.class, this) !=
                null) {
            return false;
        }
	return true;
    }


    /* The keystroke which acts as the menu item's accelerator
     */
    private KeyStroke accelerator;

    /**
     * Sets the key combination which invokes the menu item's
     * action listeners without navigating the menu hierarchy. It is the
     * UI's responsibility to install the correct action.  Note that 
     * when the keyboard accelerator is typed, it will work whether or
     * not the menu is currently displayed.
     *
     * @param keyStroke the <code>KeyStroke</code> which will
     *		serve as an accelerator 
     * @beaninfo 
     *     description: The keystroke combination which will invoke the 
     *                  JMenuItem's actionlisteners without navigating the
     *			menu hierarchy 
     *           bound: true
     *       preferred: true
     */
    public void setAccelerator(KeyStroke keyStroke) {
	KeyStroke oldAccelerator = accelerator;
        this.accelerator = keyStroke;
	firePropertyChange("accelerator", oldAccelerator, accelerator);
    }

    /**
     * Returns the <code>KeyStroke</code> which serves as an accelerator 
     * for the menu item.
     * @return a <code>KeyStroke</code> object identifying the
     *		accelerator key
     */
    public KeyStroke getAccelerator() {
        return this.accelerator;
    }

    /**
     * Factory method which sets the <code>ActionEvent</code> source's
     * properties according to values from the <code>Action</code> instance.
     * The properties which are set may differ for subclasses.
     * By default, this method sets the same properties as
     * <code>AbstractButton.configurePropertiesFromAction()</code>, plus
     * <code>Accelerator</code>.
     *
     * @param a the <code>Action</code> from which to get the properties,
     *		or <code>null</code>
     * @since 1.3
     * @see Action
     */
    protected void configurePropertiesFromAction(Action a) {
        super.configurePropertiesFromAction(a);
        KeyStroke ks = (a==null) ? null :
            (KeyStroke)a.getValue(Action.ACCELERATOR_KEY);
        setAccelerator(ks==null ? null : ks);
    }

    /**
     * Factory method which creates the <code>PropertyChangeListener</code>
     * used to update the <code>ActionEvent</code> source as properties
     * change on its <code>Action</code> instance. 
     * Subclasses may override this in order to provide their own
     * <code>PropertyChangeListener</code> if the set of
     * properties which should be kept up to date differs.
     * <p>
     * Note that <code>PropertyChangeListeners</code> should avoid holding
     * strong references to the <code>ActionEvent</code> source,
     * as this may hinder garbage collection of the <code>ActionEvent</code>
     * source and all components in its containment hierarchy.  
     *
     * @param a the <code>Action</code> from which to get the properties,
     *		or <code>null</code>
     *
     * @since 1.3
     * @see Action
     */
    protected PropertyChangeListener createActionPropertyChangeListener(Action a) {
        return new MenuItemPropertyChangeListener(this, a);
    }

    private static class MenuItemPropertyChangeListener
                extends AbstractActionPropertyChangeListener
                implements Serializable {

        MenuItemPropertyChangeListener(JMenuItem m, Action a) {
            super(m, a);
        }

        public void propertyChange(PropertyChangeEvent e) {	    
            String propertyName = e.getPropertyName();
            JMenuItem mi = (JMenuItem)getTarget();
            if (mi == null) {   //WeakRef GC'ed in 1.2
                Action action = (Action)e.getSource();
                action.removePropertyChangeListener(this);
            } else {
                if (e.getPropertyName().equals(Action.NAME)) {
                    String text = (String) e.getNewValue();
                    mi.setText(text);
                    mi.repaint();
                } else if (propertyName.equals("enabled")) {
                    Boolean enabledState = (Boolean) e.getNewValue();
                    mi.setEnabled(enabledState.booleanValue());
                    mi.repaint();
                } else if (e.getPropertyName().equals(Action.SMALL_ICON)) {
                    Icon icon = (Icon) e.getNewValue();
                    mi.setIcon(icon);
                    mi.invalidate();
                    mi.repaint();
                } else
                    if (e.getPropertyName().equals(Action.MNEMONIC_KEY)) {
                    Integer mn = (Integer) e.getNewValue();
                    mi.setMnemonic(mn.intValue());
                    mi.invalidate();
                    mi.repaint();
                } 
            }
        }
    }

    /**
     * Processes a mouse event forwarded from the
     * <code>MenuSelectionManager</code> and changes the menu
     * selection, if necessary, by using the
     * <code>MenuSelectionManager</code>'s API.
     * <p>
     * Note: you do not have to forward the event to sub-components.
     * This is done automatically by the <code>MenuSelectionManager</code>.
     *
     * @param e   a <code>MouseEvent</code>
     * @param path  the <code>MenuElement</code> path array
     * @param manager   the <code>MenuSelectionManager</code>
     */
    public void processMouseEvent(MouseEvent e,MenuElement path[],MenuSelectionManager manager) {
	processMenuDragMouseEvent(
		 new MenuDragMouseEvent(e.getComponent(), e.getID(),
					e.getWhen(),
					e.getModifiers(), e.getX(), e.getY(),
					e.getClickCount(), e.isPopupTrigger(),
					path, manager));
    }


    /**
     * Processes a key event forwarded from the 
     * <code>MenuSelectionManager</code> and changes the menu selection,
     * if necessary, by using <code>MenuSelectionManager</code>'s API.
     * <p>
     * Note: you do not have to forward the event to sub-components.
     * This is done automatically by the <code>MenuSelectionManager</code>.
     *
     * @param e  a <code>KeyEvent</code>
     * @param path the <code>MenuElement</code> path array
     * @param manager   the <code>MenuSelectionManager</code>
     */
    public void processKeyEvent(KeyEvent e,MenuElement path[],MenuSelectionManager manager) {
	if (DEBUG) {
	    System.out.println("in JMenuItem.processKeyEvent/3 for " + getText() + 
				   "  " + KeyStroke.getKeyStrokeForEvent(e));
	}
        MenuKeyEvent mke = new MenuKeyEvent(e.getComponent(), e.getID(),
					     e.getWhen(), e.getModifiers(),
					     e.getKeyCode(), e.getKeyChar(),
					     path, manager);
        processMenuKeyEvent(mke);	
    
        if (mke.isConsumed())  {
            e.consume();
        }
    }



    /**
     * Handles mouse drag in a menu.
     *
     * @param e  a <code>MenuDragMouseEvent</code> object
     */
    public void processMenuDragMouseEvent(MenuDragMouseEvent e) {
	switch (e.getID()) {
	case MouseEvent.MOUSE_ENTERED:
	    isMouseDragged = false; fireMenuDragMouseEntered(e); break;
	case MouseEvent.MOUSE_EXITED:
	    isMouseDragged = false; fireMenuDragMouseExited(e); break;
	case MouseEvent.MOUSE_DRAGGED:
	    isMouseDragged = true; fireMenuDragMouseDragged(e); break;
	case MouseEvent.MOUSE_RELEASED:
	    if(isMouseDragged) fireMenuDragMouseReleased(e); break;
	default: 
	    break;
	}
    }

    /**
     * Handles a keystroke in a menu.
     *
     * @param e  a <code>MenuKeyEvent</code> object
     */
    public void processMenuKeyEvent(MenuKeyEvent e) {
	if (DEBUG) {
	    System.out.println("in JMenuItem.processMenuKeyEvent for " + getText()+ 
				   "  " + KeyStroke.getKeyStrokeForEvent(e));
	}
	switch (e.getID()) {
	case KeyEvent.KEY_PRESSED:
	    fireMenuKeyPressed(e); break;
	case KeyEvent.KEY_RELEASED:
	    fireMenuKeyReleased(e); break;
	case KeyEvent.KEY_TYPED:
	    fireMenuKeyTyped(e); break;
	default: 
	    break;
	}
    }

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type. 
     *
     * @param event a <code>MenuMouseDragEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuDragMouseEntered(MenuDragMouseEvent event) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuDragMouseListener.class) {
                // Lazily create the event:
                ((MenuDragMouseListener)listeners[i+1]).menuDragMouseEntered(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type.  
     *
     * @param event a <code>MenuDragMouseEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuDragMouseExited(MenuDragMouseEvent event) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuDragMouseListener.class) {
                // Lazily create the event:
                ((MenuDragMouseListener)listeners[i+1]).menuDragMouseExited(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type.
     *
     * @param event a <code>MenuDragMouseEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuDragMouseDragged(MenuDragMouseEvent event) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuDragMouseListener.class) {
                // Lazily create the event:
                ((MenuDragMouseListener)listeners[i+1]).menuDragMouseDragged(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type. 
     *
     * @param event a <code>MenuDragMouseEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuDragMouseReleased(MenuDragMouseEvent event) {
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuDragMouseListener.class) {
                // Lazily create the event:
                ((MenuDragMouseListener)listeners[i+1]).menuDragMouseReleased(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type. 
     *
     * @param event a <code>MenuKeyEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuKeyPressed(MenuKeyEvent event) {
	if (DEBUG) {
	    System.out.println("in JMenuItem.fireMenuKeyPressed for " + getText()+ 
				   "  " + KeyStroke.getKeyStrokeForEvent(event));
	}
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuKeyListener.class) {
                // Lazily create the event:
                ((MenuKeyListener)listeners[i+1]).menuKeyPressed(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type. 
     *
     * @param event a <code>MenuKeyEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuKeyReleased(MenuKeyEvent event) {
	if (DEBUG) {
	    System.out.println("in JMenuItem.fireMenuKeyReleased for " + getText()+ 
				   "  " + KeyStroke.getKeyStrokeForEvent(event));
	}
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuKeyListener.class) {
                // Lazily create the event:
                ((MenuKeyListener)listeners[i+1]).menuKeyReleased(event);
            }          
        }
    }   

    /**
     * Notifies all listeners that have registered interest for
     * notification on this event type. 
     *
     * @param event a <code>MenuKeyEvent</code>
     * @see EventListenerList
     */
    protected void fireMenuKeyTyped(MenuKeyEvent event) {
	if (DEBUG) {
	    System.out.println("in JMenuItem.fireMenuKeyTyped for " + getText()+ 
				   "  " + KeyStroke.getKeyStrokeForEvent(event));
	}
        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();
        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length-2; i>=0; i-=2) {
            if (listeners[i]==MenuKeyListener.class) {
                // Lazily create the event:
                ((MenuKeyListener)listeners[i+1]).menuKeyTyped(event);
            }          
        }
    }   

    /**
     * Called by the <code>MenuSelectionManager</code> when the
     * <code>MenuElement</code> is selected or unselected.
     * 
     * @param isIncluded  true if this menu item is on the part of the menu
     *                    path that changed, false if this menu is part of the
     *                    a menu path that changed, but this particular part of
     *                    that path is still the same
     * @see MenuSelectionManager#setSelectedPath(MenuElement[])
     */
    public void menuSelectionChanged(boolean isIncluded) {
        setArmed(isIncluded);
    }

    /**
     * This method returns an array containing the sub-menu
     * components for this menu component.
     *
     * @return an array of <code>MenuElement</code>s
     */
    public MenuElement[] getSubElements() {
        return new MenuElement[0];
    }
    
    /**
     * Returns the <code>java.awt.Component</code> used to paint
     * this object. The returned component will be used to convert
     * events and detect if an event is inside a menu component.
     *
     * @return the <code>Component</code> that paints this menu item
     */
    public Component getComponent() {
        return this;
    }

    /**
     * Adds a <code>MenuDragMouseListener</code> to the menu item.
     *
     * @param l the <code>MenuDragMouseListener</code> to be added
     */
    public void addMenuDragMouseListener(MenuDragMouseListener l) {
        listenerList.add(MenuDragMouseListener.class, l);
    }

    /**
     * Removes a <code>MenuDragMouseListener</code> from the menu item.
     *
     * @param l the <code>MenuDragMouseListener</code> to be removed
     */
    public void removeMenuDragMouseListener(MenuDragMouseListener l) {
        listenerList.remove(MenuDragMouseListener.class, l);
    }

    /**
     * Returns an array of all the <code>MenuDragMouseListener</code>s added
     * to this JMenuItem with addMenuDragMouseListener().
     * 
     * @return all of the <code>MenuDragMouseListener</code>s added or an empty
     *         array if no listeners have been added
     * @since 1.4
     */
    public MenuDragMouseListener[] getMenuDragMouseListeners() {
        return (MenuDragMouseListener[])listenerList.getListeners(
                MenuDragMouseListener.class);
    }

    /**
     * Adds a <code>MenuKeyListener</code> to the menu item.
     *
     * @param l the <code>MenuKeyListener</code> to be added
     */
    public void addMenuKeyListener(MenuKeyListener l) {
        listenerList.add(MenuKeyListener.class, l);
    }

    /**
     * Removes a <code>MenuKeyListener</code> from the menu item.
     *
     * @param l the <code>MenuKeyListener</code> to be removed
     */
    public void removeMenuKeyListener(MenuKeyListener l) {
        listenerList.remove(MenuKeyListener.class, l);
    }

    /**
     * Returns an array of all the <code>MenuKeyListener</code>s added
     * to this JMenuItem with addMenuKeyListener().
     * 
     * @return all of the <code>MenuKeyListener</code>s added or an empty
     *         array if no listeners have been added
     * @since 1.4
     */
    public MenuKeyListener[] getMenuKeyListeners() {
        return (MenuKeyListener[])listenerList.getListeners(
                MenuKeyListener.class);
    }

    /**
     * See JComponent.readObject() for information about serialization
     * in Swing.
     */
    private void readObject(ObjectInputStream s) 
	throws IOException, ClassNotFoundException 
    {
        s.defaultReadObject();
	if (getUIClassID().equals(uiClassID)) {
	    updateUI();
	}
    }

    private void writeObject(ObjectOutputStream s) throws IOException {
        s.defaultWriteObject();
        if (getUIClassID().equals(uiClassID)) {
            byte count = JComponent.getWriteObjCounter(this);
            JComponent.setWriteObjCounter(this, --count);
            if (count == 0 && ui != null) {
                ui.installUI(this);
            }
        }
    }


    /**
     * Returns a string representation of this <code>JMenuItem</code>.
     * This method is intended to be used only for debugging purposes,
     * and the content and format of the returned string may vary between      
     * implementations. The returned string may be empty but may not 
     * be <code>null</code>.
     * 
     * @return  a string representation of this <code>JMenuItem</code>
     */
    protected String paramString() {
	return super.paramString();
    }

/////////////////
// Accessibility support
////////////////

    /**
     * Returns the <code>AccessibleContext</code> associated with this 
     * <code>JMenuItem</code>. For <code>JMenuItem</code>s,
     * the <code>AccessibleContext</code> takes the form of an 
     * <code>AccessibleJMenuItem</code>. 
     * A new AccessibleJMenuItme instance is created if necessary.
     *
     * @return an <code>AccessibleJMenuItem</code> that serves as the 
     *         <code>AccessibleContext</code> of this <code>JMenuItem</code>
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleJMenuItem();
        }
        return accessibleContext;
    }


    /**
     * This class implements accessibility support for the 
     * <code>JMenuItem</code> class.  It provides an implementation of the 
     * Java Accessibility API appropriate to menu item user-interface 
     * elements.
     * <p>
     * <strong>Warning:</strong>
     * Serialized objects of this class will not be compatible with
     * future Swing releases. The current serialization support is
     * appropriate for short term storage or RMI between applications running
     * the same version of Swing.  As of 1.4, support for long term storage
     * of all JavaBeans<sup><font size="-2">TM</font></sup>
     * has been added to the <code>java.beans</code> package.
     * Please see {@link java.beans.XMLEncoder}.
     */
    protected class AccessibleJMenuItem extends AccessibleAbstractButton implements ChangeListener {

	private boolean isArmed = false;
	private boolean hasFocus = false;
	private boolean isPressed = false;
	private boolean isSelected = false;

        AccessibleJMenuItem() {
            super();
            JMenuItem.this.addChangeListener(this);
        }

        /**
         * Get the role of this object.
         *
         * @return an instance of AccessibleRole describing the role of the 
         * object
         */
        public AccessibleRole getAccessibleRole() {
            return AccessibleRole.MENU_ITEM;
        }

        private void fireAccessibilityFocusedEvent(JMenuItem toCheck) {
            MenuElement [] path =
                MenuSelectionManager.defaultManager().getSelectedPath();
            if (path.length > 0) {
                Object menuItem = path[path.length - 1];
                if (toCheck == menuItem) {
                    firePropertyChange(
                        AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        null, AccessibleState.FOCUSED);
                }
            }
        }

        /**
         * Supports the change listener interface and fires property changes.
         */
        public void stateChanged(ChangeEvent e) {
            firePropertyChange(AccessibleContext.ACCESSIBLE_VISIBLE_DATA_PROPERTY, 
                               Boolean.valueOf(false), Boolean.valueOf(true));
            if (JMenuItem.this.getModel().isArmed()) {
		if (!isArmed) {
		    isArmed = true;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        null, AccessibleState.ARMED);
                    // Fix for 4848220 moved here to avoid major memory leak
                    // Here we will fire the event in case of JMenuItem 
                    // See bug 4910323 for details [zav]
                    fireAccessibilityFocusedEvent(JMenuItem.this);
		}
            } else {
		if (isArmed) {
		    isArmed = false;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleState.ARMED, null);
		}
	    }
            if (JMenuItem.this.isFocusOwner()) {
		if (!hasFocus) {
		    hasFocus = true;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        null, AccessibleState.FOCUSED);
		}
            } else {
		if (hasFocus) {
		    hasFocus = false;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleState.FOCUSED, null);
		}
	    }
            if (JMenuItem.this.getModel().isPressed()) {
		if (!isPressed) {
		    isPressed = true;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        null, AccessibleState.PRESSED);
		}
            } else {
		if (isPressed) {
		    isPressed = false;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleState.PRESSED, null);
		}
	    }
            if (JMenuItem.this.getModel().isSelected()) {
		if (!isSelected) {
		    isSelected = true;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        null, AccessibleState.CHECKED);

                    // Fix for 4848220 moved here to avoid major memory leak
                    // Here we will fire the event in case of JMenu
                    // See bug 4910323 for details [zav]
                    fireAccessibilityFocusedEvent(JMenuItem.this);
                }
            } else {
		if (isSelected) {
		    isSelected = false;
		    firePropertyChange(
	                AccessibleContext.ACCESSIBLE_STATE_PROPERTY,
                        AccessibleState.CHECKED, null);
		}
	    }

        }
    } // inner class AccessibleJMenuItem
}