java.awt
Class MenuBar

java.lang.Object
  java.awt.MenuComponent
      java.awt.MenuBar

All Implemented Interfaces:

javax.accessibility.Accessible, MenuContainer, Serializable

public class MenuBar

extends MenuComponent

implements MenuContainer, javax.accessibility.Accessible

The MenuBar class encapsulates the platform's concept of a menu bar bound to a frame. In order to associate the menu bar with a Frame object, call the frame's setMenuBar method.

This is what a menu bar might look like:

ALIGN=center HSPACE=10 VSPACE=7>

A menu bar handles keyboard shortcuts for menu items, passing them along to its child menus. (Keyboard shortcuts, which are optional, provide the user with an alternative to the mouse for invoking a menu item and the action that is associated with it.) Each menu item can maintain an instance of MenuShortcut. The MenuBar class defines several methods, shortcuts() and getShortcutMenuItem(java.awt.MenuShortcut) that retrieve information about the shortcuts a given menu bar is managing.

Since:

JDK1.0

Author:

Sami Shaio

See Also:

Frame, Frame.setMenuBar(java.awt.MenuBar), Menu, MenuItem, MenuShortcut, Serialized Form

Nested Class Summary

protected class

MenuBar.AccessibleAWTMenuBar Inner class of MenuBar used to provide default support for accessibility.

Nested classes inherited from class java.awt.MenuComponent

MenuComponent.AccessibleAWTMenuComponent

Field Summary

private static String	base
(package private) Menu	helpMenu This menu is a special menu dedicated to help.
private int	menuBarSerializedDataVersion The MenuBar's serialized data version.
(package private) Vector	menus This field represents a vector of the actual menus that will be part of the MenuBar.
private static int	nameCounter
private static long	serialVersionUID

Fields inherited from class java.awt.MenuComponent

accessibleContext, actionListenerK, appContext, font, itemListenerK, newEventsOnly, parent, peer

Constructor Summary

MenuBar()
Creates a new menu bar.

Method Summary

Menu	add(Menu m) Adds the specified menu to the menu bar.
void	addNotify() Creates the menu bar's peer.
(package private) String	constructComponentName() Construct a name for this MenuComponent.
int	countMenus() Deprecated. As of JDK version 1.1, replaced by getMenuCount().
void	deleteShortcut(MenuShortcut s) Deletes the specified menu shortcut.
javax.accessibility.AccessibleContext	getAccessibleContext() Gets the AccessibleContext associated with this MenuBar.
Menu	getHelpMenu() Gets the help menu on the menu bar.
Menu	getMenu(int i) Gets the specified menu.
int	getMenuCount() Gets the number of menus on the menu bar.
(package private) int	getMenuCountImpl()
(package private) Menu	getMenuImpl(int i)
MenuItem	getShortcutMenuItem(MenuShortcut s) Gets the instance of MenuItem associated with the specified MenuShortcut object, or null if none of the menu items being managed by this menu bar is associated with the specified menu shortcut.
(package private) boolean	handleShortcut(KeyEvent e)
private static void	initIDs() Initialize JNI field and method IDs
private void	readObject(ObjectInputStream s) Reads the ObjectInputStream.
void	remove(int index) Removes the menu located at the specified index from this menu bar.
void	remove(MenuComponent m) Removes the specified menu component from this menu bar.
void	removeNotify() Removes the menu bar's peer.
void	setHelpMenu(Menu m) Sets the specified menu to be this menu bar's help menu.
Enumeration	shortcuts() Gets an enumeration of all menu shortcuts this menu bar is managing.
private void	writeObject(ObjectOutputStream s) Writes default serializable fields to stream.

Methods inherited from class java.awt.MenuComponent

dispatchEvent, dispatchEventImpl, eventEnabled, getAccessibleIndexInParent, getAccessibleStateSet, getFont_NoClientCode, getFont, getName, getParent_NoClientCode, getParent, getPeer, getTreeLock, paramString, postEvent, processEvent, setFont, setName, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.awt.MenuContainer

getFont, postEvent

Field Detail

menus

Vector menus

This field represents a vector of the actual menus that will be part of the MenuBar.

See Also:

countMenus()

helpMenu

Menu helpMenu

This menu is a special menu dedicated to help. The one thing to note about this menu is that on some platforms it appears at the right edge of the menubar.

See Also:

getHelpMenu(), setHelpMenu(Menu)

base

private static final String base

See Also:

Constant Field Values

nameCounter

private static int nameCounter

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

menuBarSerializedDataVersion

private int menuBarSerializedDataVersion

The MenuBar's serialized data version.

Constructor Detail

MenuBar

public MenuBar()
        throws HeadlessException

Creates a new menu bar.

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

See Also:

GraphicsEnvironment.isHeadless()

Method Detail

constructComponentName

String constructComponentName()

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

Overrides:

constructComponentName in class MenuComponent

Returns:

a name for this MenuComponent

addNotify

public void addNotify()

Creates the menu bar's peer. The peer allows us to change the appearance of the menu bar without changing any of the menu bar's functionality.

removeNotify

public void removeNotify()

Removes the menu bar's peer. The peer allows us to change the appearance of the menu bar without changing any of the menu bar's functionality.

Overrides:

removeNotify in class MenuComponent

getHelpMenu

public Menu getHelpMenu()

Gets the help menu on the menu bar.

Returns:

the help menu on this menu bar.

setHelpMenu

public void setHelpMenu(Menu m)

Sets the specified menu to be this menu bar's help menu. If this menu bar has an existing help menu, the old help menu is removed from the menu bar, and replaced with the specified menu.

Parameters:

m - the menu to be set as the help menu

add

public Menu add(Menu m)

Adds the specified menu to the menu bar.

Parameters:

m - the menu to be added.

Returns:

the menu added.

See Also:

remove(int), remove(java.awt.MenuComponent)

remove

public void remove(int index)

Removes the menu located at the specified index from this menu bar.

Parameters:

index - the position of the menu to be removed.

See Also:

add(java.awt.Menu)

remove

public void remove(MenuComponent m)

Removes the specified menu component from this menu bar.

Specified by:

remove in interface MenuContainer

Parameters:

m - the menu component to be removed.

See Also:

add(java.awt.Menu)

getMenuCount

public int getMenuCount()

Gets the number of menus on the menu bar.

Returns:

the number of menus on the menu bar.

Since:

JDK1.1

countMenus

public int countMenus()

Deprecated. As of JDK version 1.1, replaced by getMenuCount().

getMenuCountImpl

final int getMenuCountImpl()

getMenu

public Menu getMenu(int i)

Gets the specified menu.

Parameters:

i - the index position of the menu to be returned.

Returns:

the menu at the specified index of this menu bar.

getMenuImpl

final Menu getMenuImpl(int i)

shortcuts

public Enumeration shortcuts()

Gets an enumeration of all menu shortcuts this menu bar is managing.

Returns:

an enumeration of menu shortcuts that this menu bar is managing.

Since:

JDK1.1

See Also:

MenuShortcut

getShortcutMenuItem

public MenuItem getShortcutMenuItem(MenuShortcut s)

Gets the instance of MenuItem associated with the specified MenuShortcut object, or null if none of the menu items being managed by this menu bar is associated with the specified menu shortcut.

Parameters:

s - the specified menu shortcut.

Since:

JDK1.1

See Also:

MenuItem, MenuShortcut

handleShortcut

boolean handleShortcut(KeyEvent e)

deleteShortcut

public void deleteShortcut(MenuShortcut s)

Deletes the specified menu shortcut.

Parameters:

s - the menu shortcut to delete.

Since:

JDK1.1

writeObject

private void writeObject(ObjectOutputStream s)
                  throws ClassNotFoundException,
                         IOException

Writes default serializable fields to stream.

Parameters:

s - the ObjectOutputStream to write

Throws:

ClassNotFoundException

IOException

See Also:

AWTEventMulticaster.save(ObjectOutputStream, String, EventListener), readObject(java.io.ObjectInputStream)

readObject

private void readObject(ObjectInputStream s)
                 throws ClassNotFoundException,
                        IOException,
                        HeadlessException

Reads the ObjectInputStream. Unrecognized keys or values will be ignored.

Parameters:

s - the ObjectInputStream to read

Throws:

HeadlessException - if GraphicsEnvironment.isHeadless returns true

ClassNotFoundException

IOException

See Also:

GraphicsEnvironment.isHeadless(), writeObject(java.io.ObjectOutputStream)

initIDs

private static void initIDs()

Initialize JNI field and method IDs

getAccessibleContext

public javax.accessibility.AccessibleContext getAccessibleContext()

Gets the AccessibleContext associated with this MenuBar. For menu bars, the AccessibleContext takes the form of an AccessibleAWTMenuBar. A new AccessibleAWTMenuBar instance is created if necessary.

Specified by:

getAccessibleContext in interface javax.accessibility.Accessible

Overrides:

getAccessibleContext in class MenuComponent

Returns:

an AccessibleAWTMenuBar that serves as the AccessibleContext of this MenuBar