https://openjdk.java.net/ 
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 * Copyright (c) 1995, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package java.awt;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.awt.peer.MenuItemPeer;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.EventListener;

import javax.accessibility.Accessible;
import javax.accessibility.AccessibleAction;
import javax.accessibility.AccessibleContext;
import javax.accessibility.AccessibleRole;
import javax.accessibility.AccessibleValue;

import sun.awt.AWTAccessor;


All items in a menu must belong to the class MenuItem, or one of its subclasses. 
 The default MenuItem object embodies a simple labeled menu item. 

This picture of a menu bar shows five menu items:


 The first two items are simple menu items, labeled "Basic" and "Simple". Following these two items is a separator, which is itself a menu item, created with the label "-". Next is an instance of CheckboxMenuItem labeled "Check". The final menu item is a submenu labeled "More Examples", and this submenu is an instance of Menu. 
 When a menu item is selected, AWT sends an action event to the menu item. Since the event is an instance of ActionEvent, the processEvent method examines the event and passes it along to processActionEvent. The latter method redirects the event to any ActionListener objects that have registered an interest in action events generated by this menu item. 
 Note that the subclass Menu overrides this behavior and does not send any event to the frame until one of its subitems is selected. 
Author:Sami Shaio
/**
 * All items in a menu must belong to the class
 * {@code MenuItem}, or one of its subclasses.
 * <p>
 * The default {@code MenuItem} object embodies
 * a simple labeled menu item.
 * <p>
 * This picture of a menu bar shows five menu items:
 * <IMG SRC="doc-files/MenuBar-1.gif" alt="The following text describes this graphic."
 * style="float:center; margin: 7px 10px;">
 * <br style="clear:left;">
 * The first two items are simple menu items, labeled
 * {@code "Basic"} and {@code "Simple"}.
 * Following these two items is a separator, which is itself
 * a menu item, created with the label {@code "-"}.
 * Next is an instance of {@code CheckboxMenuItem}
 * labeled {@code "Check"}. The final menu item is a
 * submenu labeled <code>"More&nbsp;Examples"</code>,
 * and this submenu is an instance of {@code Menu}.
 * <p>
 * When a menu item is selected, AWT sends an action event to
 * the menu item. Since the event is an
 * instance of {@code ActionEvent}, the {@code processEvent}
 * method examines the event and passes it along to
 * {@code processActionEvent}. The latter method redirects the
 * event to any {@code ActionListener} objects that have
 * registered an interest in action events generated by this
 * menu item.
 * <P>
 * Note that the subclass {@code Menu} overrides this behavior and
 * does not send any event to the frame until one of its subitems is
 * selected.
 *
 * @author Sami Shaio
 */
public class MenuItem extends MenuComponent implements Accessible {

    static {
        /* ensure that the necessary native libraries are loaded */
        Toolkit.loadLibraries();
        if (!GraphicsEnvironment.isHeadless()) {
            initIDs();
        }

        AWTAccessor.setMenuItemAccessor(
            new AWTAccessor.MenuItemAccessor() {
                public boolean isEnabled(MenuItem item) {
                    return item.enabled;
                }

                public String getLabel(MenuItem item) {
                    return item.label;
                }

                public MenuShortcut getShortcut(MenuItem item) {
                    return item.shortcut;
                }

                public String getActionCommandImpl(MenuItem item) {
                    return item.getActionCommandImpl();
                }

                public boolean isItemEnabled(MenuItem item) {
                    return item.isItemEnabled();
                }
            });
    }

    
A value to indicate whether a menu item is enabled or not. If it is enabled, enabled will be set to true. Else enabled will be set to false. 
See Also:
@serial
/**
     * A value to indicate whether a menu item is enabled
     * or not.  If it is enabled, {@code enabled} will
     * be set to true.  Else {@code enabled} will
     * be set to false.
     *
     * @serial
     * @see #isEnabled()
     * @see #setEnabled(boolean)
     */
    private volatile boolean enabled = true;

    
label is the label of a menu item. It can be any string. 
See Also:
@serial
/**
     * {@code label} is the label of a menu item.
     * It can be any string.
     *
     * @serial
     * @see #getLabel()
     * @see #setLabel(String)
     */
    volatile String label;

    
This field indicates the command that has been issued by a particular menu item. By default the actionCommand is the label of the menu item, unless it has been set using setActionCommand. 
See Also:
@serial
/**
     * This field indicates the command that has been issued
     * by a  particular menu item.
     * By default the {@code actionCommand}
     * is the label of the menu item, unless it has been
     * set using setActionCommand.
     *
     * @serial
     * @see #setActionCommand(String)
     * @see #getActionCommand()
     */
    private volatile String actionCommand;

    
The eventMask is ONLY set by subclasses via enableEvents.
The mask should NOT be set when listeners are registered
so that we can distinguish the difference between when
listeners request events and subclasses request them.

@serial
/**
     * The eventMask is ONLY set by subclasses via enableEvents.
     * The mask should NOT be set when listeners are registered
     * so that we can distinguish the difference between when
     * listeners request events and subclasses request them.
     *
     * @serial
     */
    volatile long eventMask;

    private transient volatile ActionListener actionListener;

    
A sequence of key stokes that ia associated with
a menu item.
Note :in 1.1.2 you must use setActionCommand()
on a menu item in order for its shortcut to
work.

See Also:
@serial
/**
     * A sequence of key stokes that ia associated with
     * a menu item.
     * Note :in 1.1.2 you must use setActionCommand()
     * on a menu item in order for its shortcut to
     * work.
     *
     * @serial
     * @see #getShortcut()
     * @see #setShortcut(MenuShortcut)
     * @see #deleteShortcut()
     */
    private volatile MenuShortcut shortcut;

    private static final String base = "menuitem";
    private static int nameCounter = 0;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = -21757335363267194L;

    
Constructs a new MenuItem with an empty label and no keyboard
shortcut.

Throws:
  • HeadlessException – if GraphicsEnvironment.isHeadless()
returns true.
See Also:
Since:   1.1
/**
     * Constructs a new MenuItem with an empty label and no keyboard
     * shortcut.
     * @exception HeadlessException if GraphicsEnvironment.isHeadless()
     * returns true.
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since    1.1
     */
    public MenuItem() throws HeadlessException {
        this("", null);
    }

    
Constructs a new MenuItem with the specified label
and no keyboard shortcut. Note that use of "-" in
a label is reserved to indicate a separator between
menu items. By default, all menu items except for
separators are enabled.

Params:
  • label – the label for this menu item.
Throws:
See Also:
Since:      1.0
/**
     * Constructs a new MenuItem with the specified label
     * and no keyboard shortcut. Note that use of "-" in
     * a label is reserved to indicate a separator between
     * menu items. By default, all menu items except for
     * separators are enabled.
     * @param       label the label for this menu item.
     * @exception HeadlessException if GraphicsEnvironment.isHeadless()
     * returns true.
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since       1.0
     */
    public MenuItem(String label) throws HeadlessException {
        this(label, null);
    }

    
Create a menu item with an associated keyboard shortcut.
Note that use of "-" in a label is reserved to indicate
a separator between menu items. By default, all menu
items except for separators are enabled.

Params:
  • label – the label for this menu item.
  • s – the instance of MenuShortcut associated with this menu item.
Throws:
See Also:
Since:      1.1
/**
     * Create a menu item with an associated keyboard shortcut.
     * Note that use of "-" in a label is reserved to indicate
     * a separator between menu items. By default, all menu
     * items except for separators are enabled.
     * @param       label the label for this menu item.
     * @param       s the instance of {@code MenuShortcut}
     *                       associated with this menu item.
     * @exception HeadlessException if GraphicsEnvironment.isHeadless()
     * returns true.
     * @see java.awt.GraphicsEnvironment#isHeadless
     * @since       1.1
     */
    public MenuItem(String label, MenuShortcut s) throws HeadlessException {
        this.label = label;
        this.shortcut = s;
    }

    
Construct a name for this MenuComponent.  Called by getName() when
the name is null.

/**
     * Construct a name for this MenuComponent.  Called by getName() when
     * the name is null.
     */
    String constructComponentName() {
        synchronized (MenuItem.class) {
            return base + nameCounter++;
        }
    }

    
Creates the menu item's peer.  The peer allows us to modify the
appearance of the menu item without changing its functionality.

/**
     * Creates the menu item's peer.  The peer allows us to modify the
     * appearance of the menu item without changing its functionality.
     */
    public void addNotify() {
        synchronized (getTreeLock()) {
            if (peer == null)
                peer = getComponentFactory().createMenuItem(this);
        }
    }

    
Gets the label for this menu item.

See Also:
Returns: the label of this menu item, or null if this menu item has no label.
Since:  1.0
/**
     * Gets the label for this menu item.
     * @return  the label of this menu item, or {@code null}
                       if this menu item has no label.
     * @see     java.awt.MenuItem#setLabel
     * @since   1.0
     */
    public String getLabel() {
        return label;
    }

    
Sets the label for this menu item to the specified label.

Params:
  • label –  the new label, or null for no label.
See Also:
Since:    1.0
/**
     * Sets the label for this menu item to the specified label.
     * @param     label   the new label, or {@code null} for no label.
     * @see       java.awt.MenuItem#getLabel
     * @since     1.0
     */
    public synchronized void setLabel(String label) {
        this.label = label;
        MenuItemPeer peer = (MenuItemPeer)this.peer;
        if (peer != null) {
            peer.setLabel(label);
        }
    }

    
Checks whether this menu item is enabled.

See Also:
Returns:true if the item is enabled; otherwise false
Since:     1.0
/**
     * Checks whether this menu item is enabled.
     *
     * @return {@code true} if the item is enabled;
     *         otherwise {@code false}
     * @see        java.awt.MenuItem#setEnabled
     * @since      1.0
     */
    public boolean isEnabled() {
        return enabled;
    }

    
Sets whether or not this menu item can be chosen.

Params:
  • b –  if true, enables this menu item; if false, disables it.
See Also:
Since:     1.1
/**
     * Sets whether or not this menu item can be chosen.
     * @param      b  if {@code true}, enables this menu item;
     *                       if {@code false}, disables it.
     * @see        java.awt.MenuItem#isEnabled
     * @since      1.1
     */
    public synchronized void setEnabled(boolean b) {
        enable(b);
    }

    
Deprecated:As of JDK version 1.1, replaced by setEnabled(boolean).
/**
     * @deprecated As of JDK version 1.1,
     * replaced by {@code setEnabled(boolean)}.
     */
    @Deprecated
    public synchronized void enable() {
        enabled = true;
        MenuItemPeer peer = (MenuItemPeer)this.peer;
        if (peer != null) {
            peer.setEnabled(true);
        }
    }

    
Sets whether or not this menu item can be chosen.

Params:
  • b – if true, enables this menu item; otherwise disables
Deprecated:As of JDK version 1.1, replaced by setEnabled(boolean).
/**
     * Sets whether or not this menu item can be chosen.
     *
     * @param  b if {@code true}, enables this menu item;
     *           otherwise disables
     * @deprecated As of JDK version 1.1,
     * replaced by {@code setEnabled(boolean)}.
     */
    @Deprecated
    public void enable(boolean b) {
        if (b) {
            enable();
        } else {
            disable();
        }
    }

    
Deprecated:As of JDK version 1.1, replaced by setEnabled(boolean).
/**
     * @deprecated As of JDK version 1.1,
     * replaced by {@code setEnabled(boolean)}.
     */
    @Deprecated
    public synchronized void disable() {
        enabled = false;
        MenuItemPeer peer = (MenuItemPeer)this.peer;
        if (peer != null) {
            peer.setEnabled(false);
        }
    }

    
Get the MenuShortcut object associated with this menu item, 
See Also:
Returns: the menu shortcut associated with this menu item, or null if none has been specified.
Since:      1.1
/**
     * Get the {@code MenuShortcut} object associated with this
     * menu item,
     * @return      the menu shortcut associated with this menu item,
     *                   or {@code null} if none has been specified.
     * @see         java.awt.MenuItem#setShortcut
     * @since       1.1
     */
    public MenuShortcut getShortcut() {
        return shortcut;
    }

    
Set the MenuShortcut object associated with this menu item. If a menu shortcut is already associated with this menu item, it is replaced. 
Params:
  • s –  the menu shortcut to associate
                          with this menu item.
See Also:
Since:      1.1
/**
     * Set the {@code MenuShortcut} object associated with this
     * menu item. If a menu shortcut is already associated with
     * this menu item, it is replaced.
     * @param       s  the menu shortcut to associate
     *                           with this menu item.
     * @see         java.awt.MenuItem#getShortcut
     * @since       1.1
     */
    public void setShortcut(MenuShortcut s) {
        shortcut = s;
        MenuItemPeer peer = (MenuItemPeer)this.peer;
        if (peer != null) {
            peer.setLabel(label);
        }
    }

    
Delete any MenuShortcut object associated with this menu item. 
Since:     1.1
/**
     * Delete any {@code MenuShortcut} object associated
     * with this menu item.
     * @since      1.1
     */
    public void deleteShortcut() {
        shortcut = null;
        MenuItemPeer peer = (MenuItemPeer)this.peer;
        if (peer != null) {
            peer.setLabel(label);
        }
    }

    /*
     * Delete a matching MenuShortcut associated with this MenuItem.
     * Used when iterating Menus.
     */
    void deleteShortcut(MenuShortcut s) {
        if (s.equals(shortcut)) {
            shortcut = null;
            MenuItemPeer peer = (MenuItemPeer)this.peer;
            if (peer != null) {
                peer.setLabel(label);
            }
        }
    }

    /*
     * The main goal of this method is to post an appropriate event
     * to the event queue when menu shortcut is pressed. However,
     * in subclasses this method may do more than just posting
     * an event.
     */
    void doMenuEvent(long when, int modifiers) {
        Toolkit.getEventQueue().postEvent(
            new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
                            getActionCommand(), when, modifiers));
    }

    /*
     * Returns true if the item and all its ancestors are
     * enabled, false otherwise
     */
    private boolean isItemEnabled() {
        // Fix For 6185151: Menu shortcuts of all menuitems within a menu
        // should be disabled when the menu itself is disabled
        if (!isEnabled()) {
            return false;
        }
        MenuContainer container = getParent_NoClientCode();
        do {
            if (!(container instanceof Menu)) {
                return true;
            }
            Menu menu = (Menu)container;
            if (!menu.isEnabled()) {
                return false;
            }
            container = menu.getParent_NoClientCode();
        } while (container != null);
        return true;
    }

    /*
     * Post an ActionEvent to the target (on
     * keydown) and the item is enabled.
     * Returns true if there is an associated shortcut.
     */
    @SuppressWarnings("deprecation")
    boolean handleShortcut(KeyEvent e) {
        MenuShortcut s = new MenuShortcut(e.getKeyCode(),
                             (e.getModifiers() & InputEvent.SHIFT_MASK) > 0);
        MenuShortcut sE = new MenuShortcut(e.getExtendedKeyCode(),
                             (e.getModifiers() & InputEvent.SHIFT_MASK) > 0);
        // Fix For 6185151: Menu shortcuts of all menuitems within a menu
        // should be disabled when the menu itself is disabled
        if ((s.equals(shortcut) || sE.equals(shortcut)) && isItemEnabled()) {
            // MenuShortcut match -- issue an event on keydown.
            if (e.getID() == KeyEvent.KEY_PRESSED) {
                doMenuEvent(e.getWhen(), e.getModifiers());
            } else {
                // silently eat key release.
            }
            return true;
        }
        return false;
    }

    MenuItem getShortcutMenuItem(MenuShortcut s) {
        return (s.equals(shortcut)) ? this : null;
    }

    
Enables event delivery to this menu item for events
to be defined by the specified event mask parameter

 Since event types are automatically enabled when a listener for that type is added to the menu item, this method only needs to be invoked by subclasses of MenuItem which desire to have the specified event types delivered to processEvent regardless of whether a listener is registered. 
Params:
  • eventsToEnable – the event mask defining the event types
See Also:
Since:      1.1
/**
     * Enables event delivery to this menu item for events
     * to be defined by the specified event mask parameter
     * <p>
     * Since event types are automatically enabled when a listener for
     * that type is added to the menu item, this method only needs
     * to be invoked by subclasses of {@code MenuItem} which desire to
     * have the specified event types delivered to {@code processEvent}
     * regardless of whether a listener is registered.
     *
     * @param       eventsToEnable the event mask defining the event types
     * @see         java.awt.MenuItem#processEvent
     * @see         java.awt.MenuItem#disableEvents
     * @see         java.awt.Component#enableEvents
     * @since       1.1
     */
    protected final void enableEvents(long eventsToEnable) {
        eventMask |= eventsToEnable;
        newEventsOnly = true;
    }

    
Disables event delivery to this menu item for events
defined by the specified event mask parameter.

Params:
  • eventsToDisable – the event mask defining the event types
See Also:
Since:      1.1
/**
     * Disables event delivery to this menu item for events
     * defined by the specified event mask parameter.
     *
     * @param       eventsToDisable the event mask defining the event types
     * @see         java.awt.MenuItem#processEvent
     * @see         java.awt.MenuItem#enableEvents
     * @see         java.awt.Component#disableEvents
     * @since       1.1
     */
    protected final void disableEvents(long eventsToDisable) {
        eventMask &= ~eventsToDisable;
    }

    
Sets the command name of the action event that is fired
by this menu item.


By default, the action command is set to the label of
the menu item.

Params:
  • command –   the action command to be set
                               for this menu item.
See Also:
Since:      1.1
/**
     * Sets the command name of the action event that is fired
     * by this menu item.
     * <p>
     * By default, the action command is set to the label of
     * the menu item.
     * @param       command   the action command to be set
     *                                for this menu item.
     * @see         java.awt.MenuItem#getActionCommand
     * @since       1.1
     */
    public void setActionCommand(String command) {
        actionCommand = command;
    }

    
Gets the command name of the action event that is fired
by this menu item.

See Also:
Returns:the action command name
Since:1.1
/**
     * Gets the command name of the action event that is fired
     * by this menu item.
     *
     * @return the action command name
     * @see java.awt.MenuItem#setActionCommand
     * @since 1.1
     */
    public String getActionCommand() {
        return getActionCommandImpl();
    }

    // This is final so it can be called on the Toolkit thread.
    final String getActionCommandImpl() {
        return (actionCommand == null? label : actionCommand);
    }

    
Adds the specified action listener to receive action events
from this menu item.
If l is null, no exception is thrown and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l – the action listener.
See Also:
Since:     1.1
/**
     * Adds the specified action listener to receive action events
     * from this menu item.
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param      l the action listener.
     * @see        #removeActionListener
     * @see        #getActionListeners
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.event.ActionListener
     * @since      1.1
     */
    public synchronized void addActionListener(ActionListener l) {
        if (l == null) {
            return;
        }
        actionListener = AWTEventMulticaster.add(actionListener, l);
        newEventsOnly = true;
    }

    
Removes the specified action listener so it no longer receives
action events from this menu item.
If l is null, no exception is thrown and no action is performed.

Refer to AWT Threading Issues for details on AWT's threading model.

Params:
  • l – the action listener.
See Also:
Since:     1.1
/**
     * Removes the specified action listener so it no longer receives
     * action events from this menu item.
     * If l is null, no exception is thrown and no action is performed.
     * <p>Refer to <a href="doc-files/AWTThreadIssues.html#ListenersThreads"
     * >AWT Threading Issues</a> for details on AWT's threading model.
     *
     * @param      l the action listener.
     * @see        #addActionListener
     * @see        #getActionListeners
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.event.ActionListener
     * @since      1.1
     */
    public synchronized void removeActionListener(ActionListener l) {
        if (l == null) {
            return;
        }
        actionListener = AWTEventMulticaster.remove(actionListener, l);
    }

    
Returns an array of all the action listeners
registered on this menu item.

See Also:
Returns:all of this menu item's ActionListeners or an empty array if no action listeners are currently registered
Since:1.4
/**
     * Returns an array of all the action listeners
     * registered on this menu item.
     *
     * @return all of this menu item's {@code ActionListener}s
     *         or an empty array if no action
     *         listeners are currently registered
     *
     * @see        #addActionListener
     * @see        #removeActionListener
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.event.ActionListener
     * @since 1.4
     */
    public synchronized ActionListener[] getActionListeners() {
        return getListeners(ActionListener.class);
    }

    
Returns an array of all the objects currently registered
as FooListeners upon this MenuItem. FooListeners are registered using the
addFooListener method.

 You can specify the listenerType argument with a class literal, such as FooListener.class. For example, you can query a MenuItem m for its action listeners with the following code: 
ActionListener[] als = (ActionListener[])(m.getListeners(ActionListener.class));

If no such listeners exist, this method returns an empty array.

Params:
  • listenerType – the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
Type parameters:
  • <T> – the type of the listeners
Throws:
  • ClassCastException – if listenerType doesn't specify a class or interface that implements java.util.EventListener
See Also:
Returns:an array of all objects registered as
         FooListeners on this menu item,
         or an empty array if no such
         listeners have been added
Since:1.3
/**
     * Returns an array of all the objects currently registered
     * as <code><em>Foo</em>Listener</code>s
     * upon this {@code MenuItem}.
     * <code><em>Foo</em>Listener</code>s are registered using the
     * <code>add<em>Foo</em>Listener</code> method.
     *
     * <p>
     * You can specify the {@code listenerType} argument
     * with a class literal, such as
     * <code><em>Foo</em>Listener.class</code>.
     * For example, you can query a
     * {@code MenuItem m}
     * for its action listeners with the following code:
     *
     * <pre>ActionListener[] als = (ActionListener[])(m.getListeners(ActionListener.class));</pre>
     *
     * If no such listeners exist, this method returns an empty array.
     *
     * @param <T> the type of the listeners
     * @param listenerType the type of listeners requested; this parameter
     *          should specify an interface that descends from
     *          {@code java.util.EventListener}
     * @return an array of all objects registered as
     *          <code><em>Foo</em>Listener</code>s on this menu item,
     *          or an empty array if no such
     *          listeners have been added
     * @exception ClassCastException if {@code listenerType}
     *          doesn't specify a class or interface that implements
     *          {@code java.util.EventListener}
     *
     * @see #getActionListeners
     * @since 1.3
     */
    public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
        EventListener l = null;
        if  (listenerType == ActionListener.class) {
            l = actionListener;
        }
        return AWTEventMulticaster.getListeners(l, listenerType);
    }

    
Processes events on this menu item. If the event is an instance of ActionEvent, it invokes processActionEvent, another method defined by MenuItem. 

Currently, menu items only support action events.

Note that if the event parameter is null the behavior is unspecified and may result in an exception. 
Params:
  • e – the event
See Also:
Since:      1.1
/**
     * Processes events on this menu item. If the event is an
     * instance of {@code ActionEvent}, it invokes
     * {@code processActionEvent}, another method
     * defined by {@code MenuItem}.
     * <p>
     * Currently, menu items only support action events.
     * <p>Note that if the event parameter is {@code null}
     * the behavior is unspecified and may result in an
     * exception.
     *
     * @param       e the event
     * @see         java.awt.MenuItem#processActionEvent
     * @since       1.1
     */
    protected void processEvent(AWTEvent e) {
        if (e instanceof ActionEvent) {
            processActionEvent((ActionEvent)e);
        }
    }

    // REMIND: remove when filtering is done at lower level
    boolean eventEnabled(AWTEvent e) {
        if (e.id == ActionEvent.ACTION_PERFORMED) {
            if ((eventMask & AWTEvent.ACTION_EVENT_MASK) != 0 ||
                actionListener != null) {
                return true;
            }
            return false;
        }
        return super.eventEnabled(e);
    }

    
Processes action events occurring on this menu item, by dispatching them to any registered ActionListener objects. This method is not called unless action events are enabled for this component. Action events are enabled when one of the following occurs: 
    

  • An ActionListener object is registered via addActionListener. 
  • Action events are enabled via enableEvents. 


Note that if the event parameter is null the behavior is unspecified and may result in an exception. 
Params:
  • e – the action event
See Also:
Since:      1.1
/**
     * Processes action events occurring on this menu item,
     * by dispatching them to any registered
     * {@code ActionListener} objects.
     * This method is not called unless action events are
     * enabled for this component. Action events are enabled
     * when one of the following occurs:
     * <ul>
     * <li>An {@code ActionListener} object is registered
     * via {@code addActionListener}.
     * <li>Action events are enabled via {@code enableEvents}.
     * </ul>
     * <p>Note that if the event parameter is {@code null}
     * the behavior is unspecified and may result in an
     * exception.
     *
     * @param       e the action event
     * @see         java.awt.event.ActionEvent
     * @see         java.awt.event.ActionListener
     * @see         java.awt.MenuItem#enableEvents
     * @since       1.1
     */
    protected void processActionEvent(ActionEvent e) {
        ActionListener listener = actionListener;
        if (listener != null) {
            listener.actionPerformed(e);
        }
    }

    
Returns a string representing the state of this MenuItem. 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 null. 
Returns:the parameter string of this menu item
/**
     * Returns a string representing the state of this {@code MenuItem}.
     * 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}.
     *
     * @return the parameter string of this menu item
     */
    public String paramString() {
        String str = ",label=" + label;
        if (shortcut != null) {
            str += ",shortcut=" + shortcut;
        }
        return super.paramString() + str;
    }


    /* Serialization support.
     */

    
Menu item serialized data version.

@serial
/**
     * Menu item serialized data version.
     *
     * @serial
     */
    private int menuItemSerializedDataVersion = 1;

    
Writes default serializable fields to stream. Writes a list of serializable ActionListeners as optional data. The non-serializable listeners are detected and no attempt is made to serialize them. 
Params:
  • s – the ObjectOutputStream to write
See Also:
@serialDatanull terminated sequence of 0 or more pairs; the pair consists of a String and an Object; the String indicates the type of object and is one of the following: actionListenerK indicating an ActionListener object
/**
     * Writes default serializable fields to stream.  Writes
     * a list of serializable {@code ActionListeners}
     * as optional data. The non-serializable listeners are
     * detected and no attempt is made to serialize them.
     *
     * @param s the {@code ObjectOutputStream} to write
     * @serialData {@code null} terminated sequence of 0
     *   or more pairs; the pair consists of a {@code String}
     *   and an {@code Object}; the {@code String}
     *   indicates the type of object and is one of the following:
     *   {@code actionListenerK} indicating an
     *     {@code ActionListener} object
     *
     * @see AWTEventMulticaster#save(ObjectOutputStream, String, EventListener)
     * @see #readObject(ObjectInputStream)
     */
    private void writeObject(ObjectOutputStream s)
      throws IOException
    {
      s.defaultWriteObject();

      AWTEventMulticaster.save(s, actionListenerK, actionListener);
      s.writeObject(null);
    }

    
Reads the ObjectInputStream and if it isn't null adds a listener to receive action events fired by the Menu Item. Unrecognized keys or values will be ignored. 
Params:
  • s – the ObjectInputStream to read
Throws:
See Also:
/**
     * Reads the {@code ObjectInputStream} and if it
     * isn't {@code null} adds a listener to receive
     * action events fired by the {@code Menu} Item.
     * Unrecognized keys or values will be ignored.
     *
     * @param s the {@code ObjectInputStream} to read
     * @exception HeadlessException if
     *   {@code GraphicsEnvironment.isHeadless} returns
     *   {@code true}
     * @see #removeActionListener(ActionListener)
     * @see #addActionListener(ActionListener)
     * @see #writeObject(ObjectOutputStream)
     */
    private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException, HeadlessException
    {
      // HeadlessException will be thrown from MenuComponent's readObject
      s.defaultReadObject();

      Object keyOrNull;
      while(null != (keyOrNull = s.readObject())) {
        String key = ((String)keyOrNull).intern();

        if (actionListenerK == key)
          addActionListener((ActionListener)(s.readObject()));

        else // skip value for unrecognized key
          s.readObject();
      }
    }

    
Initialize JNI field and method IDs

/**
     * Initialize JNI field and method IDs
     */
    private static native void initIDs();


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

    
Gets the AccessibleContext associated with this MenuItem.
For menu items, the AccessibleContext takes the form of an
AccessibleAWTMenuItem.
A new AccessibleAWTMenuItem instance is created if necessary.

Returns:an AccessibleAWTMenuItem that serves as the
        AccessibleContext of this MenuItem
Since:1.3
/**
     * Gets the AccessibleContext associated with this MenuItem.
     * For menu items, the AccessibleContext takes the form of an
     * AccessibleAWTMenuItem.
     * A new AccessibleAWTMenuItem instance is created if necessary.
     *
     * @return an AccessibleAWTMenuItem that serves as the
     *         AccessibleContext of this MenuItem
     * @since 1.3
     */
    public AccessibleContext getAccessibleContext() {
        if (accessibleContext == null) {
            accessibleContext = new AccessibleAWTMenuItem();
        }
        return accessibleContext;
    }

    
Inner class of MenuItem used to provide default support for
accessibility.  This class is not meant to be used directly by
application developers, but is instead meant only to be
subclassed by menu component developers.

 This class implements accessibility support for the MenuItem class. It provides an implementation of the Java Accessibility API appropriate to menu item user-interface elements. 
Since:1.3
/**
     * Inner class of MenuItem used to provide default support for
     * accessibility.  This class is not meant to be used directly by
     * application developers, but is instead meant only to be
     * subclassed by menu component developers.
     * <p>
     * This class implements accessibility support for the
     * {@code MenuItem} class.  It provides an implementation of the
     * Java Accessibility API appropriate to menu item user-interface elements.
     * @since 1.3
     */
    protected class AccessibleAWTMenuItem extends AccessibleAWTMenuComponent
        implements AccessibleAction, AccessibleValue
    {
        /*
         * JDK 1.3 serialVersionUID
         */
        private static final long serialVersionUID = -217847831945965825L;

        
Get the accessible name of this object.

Returns:the localized name of the object -- can be null if this
object does not have a name
/**
         * Get the accessible name of this object.
         *
         * @return the localized name of the object -- can be null if this
         * object does not have a name
         */
        public String getAccessibleName() {
            if (accessibleName != null) {
                return accessibleName;
            } else {
                if (getLabel() == null) {
                    return super.getAccessibleName();
                } else {
                    return getLabel();
                }
            }
        }

        
Get the role of this object.

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

        
Get the AccessibleAction associated with this object.  In the
implementation of the Java Accessibility API for this class,
return this object, which is responsible for implementing the
AccessibleAction interface on behalf of itself.

Returns:this object
/**
         * Get the AccessibleAction associated with this object.  In the
         * implementation of the Java Accessibility API for this class,
         * return this object, which is responsible for implementing the
         * AccessibleAction interface on behalf of itself.
         *
         * @return this object
         */
        public AccessibleAction getAccessibleAction() {
            return this;
        }

        
Get the AccessibleValue associated with this object.  In the
implementation of the Java Accessibility API for this class,
return this object, which is responsible for implementing the
AccessibleValue interface on behalf of itself.

Returns:this object
/**
         * Get the AccessibleValue associated with this object.  In the
         * implementation of the Java Accessibility API for this class,
         * return this object, which is responsible for implementing the
         * AccessibleValue interface on behalf of itself.
         *
         * @return this object
         */
        public AccessibleValue getAccessibleValue() {
            return this;
        }

        
Returns the number of Actions available in this object.  The
default behavior of a menu item is to have one action.

Returns:1, the number of Actions in this object
/**
         * Returns the number of Actions available in this object.  The
         * default behavior of a menu item is to have one action.
         *
         * @return 1, the number of Actions in this object
         */
        public int getAccessibleActionCount() {
            return 1;
        }

        
Return a description of the specified action of the object.

Params:
  • i – zero-based index of the actions
/**
         * Return a description of the specified action of the object.
         *
         * @param i zero-based index of the actions
         */
        public String getAccessibleActionDescription(int i) {
            if (i == 0) {
                // [[[PENDING:  WDW -- need to provide a localized string]]]
                return "click";
            } else {
                return null;
            }
        }

        
Perform the specified Action on the object

Params:
  • i – zero-based index of actions
Returns:true if the action was performed; otherwise false.
/**
         * Perform the specified Action on the object
         *
         * @param i zero-based index of actions
         * @return true if the action was performed; otherwise false.
         */
        public boolean doAccessibleAction(int i) {
            if (i == 0) {
                // Simulate a button click
                Toolkit.getEventQueue().postEvent(
                        new ActionEvent(MenuItem.this,
                                        ActionEvent.ACTION_PERFORMED,
                                        MenuItem.this.getActionCommand(),
                                        EventQueue.getMostRecentEventTime(),
                                        0));
                return true;
            } else {
                return false;
            }
        }

        
Get the value of this object as a Number.

See Also:
Returns:An Integer of 0 if this isn't selected or an Integer of 1 if
this is selected.
/**
         * Get the value of this object as a Number.
         *
         * @return An Integer of 0 if this isn't selected or an Integer of 1 if
         * this is selected.
         * @see javax.swing.AbstractButton#isSelected()
         */
        public Number getCurrentAccessibleValue() {
            return Integer.valueOf(0);
        }

        
Set the value of this object as a Number.

Returns:True if the value was set.
/**
         * Set the value of this object as a Number.
         *
         * @return True if the value was set.
         */
        public boolean setCurrentAccessibleValue(Number n) {
            return false;
        }

        
Get the minimum value of this object as a Number.

Returns:An Integer of 0.
/**
         * Get the minimum value of this object as a Number.
         *
         * @return An Integer of 0.
         */
        public Number getMinimumAccessibleValue() {
            return Integer.valueOf(0);
        }

        
Get the maximum value of this object as a Number.

Returns:An Integer of 0.
/**
         * Get the maximum value of this object as a Number.
         *
         * @return An Integer of 0.
         */
        public Number getMaximumAccessibleValue() {
            return Integer.valueOf(0);
        }

    } // class AccessibleAWTMenuItem

}