public class

MenuItem

extends MenuComponent
implements Accessible
java.lang.Object
   ↳ java.awt.MenuComponent
     ↳ java.awt.MenuItem
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

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 following text describes this graphic.
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.

Summary

Nested Classes
class MenuItem.AccessibleAWTMenuItem Inner class of MenuItem used to provide default support for accessibility. 
Public Constructors
MenuItem()
Constructs a new MenuItem with an empty label and no keyboard shortcut.
MenuItem(String label)
Constructs a new MenuItem with the specified label and no keyboard shortcut.
MenuItem(String label, MenuShortcut s)
Create a menu item with an associated keyboard shortcut.
Public Methods
synchronized void addActionListener(ActionListener l)
Adds the specified action listener to receive action events from this menu item.
void addNotify()
Creates the menu item's peer.
void deleteShortcut()
Delete any MenuShortcut object associated with this menu item.
synchronized void disable()
This method is deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).
synchronized void enable()
This method is deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).
void enable(boolean b)
This method is deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).
AccessibleContext getAccessibleContext()
Gets the AccessibleContext associated with this MenuItem.
String getActionCommand()
Gets the command name of the action event that is fired by this menu item.
synchronized ActionListener[] getActionListeners()
Returns an array of all the action listeners registered on this menu item.
String getLabel()
Gets the label for this menu item.
<T extends EventListener> T[] getListeners(Class<T> listenerType)
Returns an array of all the objects currently registered as FooListeners upon this MenuItem.
MenuShortcut getShortcut()
Get the MenuShortcut object associated with this menu item,
boolean isEnabled()
Checks whether this menu item is enabled.
String paramString()
Returns a string representing the state of this MenuItem.
synchronized void removeActionListener(ActionListener l)
Removes the specified action listener so it no longer receives action events from this menu item.
void setActionCommand(String command)
Sets the command name of the action event that is fired by this menu item.
synchronized void setEnabled(boolean b)
Sets whether or not this menu item can be chosen.
synchronized void setLabel(String label)
Sets the label for this menu item to the specified label.
void setShortcut(MenuShortcut s)
Set the MenuShortcut object associated with this menu item.
Protected Methods
final void disableEvents(long eventsToDisable)
Disables event delivery to this menu item for events defined by the specified event mask parameter.
final void enableEvents(long eventsToEnable)
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.

void processActionEvent(ActionEvent e)
Processes action events occurring on this menu item, by dispatching them to any registered ActionListener objects.
void processEvent(AWTEvent e)
Processes events on this menu item.
[Expand]
Inherited Methods
From class java.awt.MenuComponent
From class java.lang.Object
From interface javax.accessibility.Accessible

Public Constructors

public MenuItem ()

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

Throws
HeadlessException if GraphicsEnvironment.isHeadless() returns true.
See Also

public MenuItem (String label)

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.

Parameters
label the label for this menu item.
Throws
HeadlessException if GraphicsEnvironment.isHeadless() returns true.
See Also

public MenuItem (String label, MenuShortcut s)

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.

Parameters
label the label for this menu item.
s the instance of MenuShortcut associated with this menu item.
Throws
HeadlessException if GraphicsEnvironment.isHeadless() returns true.
See Also

Public Methods

public synchronized void addActionListener (ActionListener l)

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.

Parameters
l the action listener.
See Also

public void addNotify ()

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

public void deleteShortcut ()

Delete any MenuShortcut object associated with this menu item.

public synchronized void disable ()

This method is deprecated.
As of JDK version 1.1, replaced by setEnabled(boolean).

public synchronized void enable ()

This method is deprecated.
As of JDK version 1.1, replaced by setEnabled(boolean).

public void enable (boolean b)

This method is deprecated.
As of JDK version 1.1, replaced by setEnabled(boolean).

public AccessibleContext getAccessibleContext ()

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

public String getActionCommand ()

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

See Also

public synchronized ActionListener[] getActionListeners ()

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

Returns
  • all of this menu item's ActionListeners or an empty array if no action listeners are currently registered
See Also

public String getLabel ()

Gets the label for this menu item.

Returns
  • the label of this menu item, or null if this menu item has no label.
See Also

public T[] getListeners (Class<T> listenerType)

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.

Parameters
listenerType the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
Returns
  • an array of all objects registered as FooListeners on this menu item, or an empty array if no such listeners have been added
Throws
ClassCastException if listenerType doesn't specify a class or interface that implements java.util.EventListener
See Also

public MenuShortcut getShortcut ()

Get the MenuShortcut object associated with this menu item,

Returns
  • the menu shortcut associated with this menu item, or null if none has been specified.
See Also

public boolean isEnabled ()

Checks whether this menu item is enabled.

See Also

public String paramString ()

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

public synchronized void removeActionListener (ActionListener l)

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.

Parameters
l the action listener.
See Also

public void setActionCommand (String command)

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.

Parameters
command the action command to be set for this menu item.
See Also

public synchronized void setEnabled (boolean b)

Sets whether or not this menu item can be chosen.

Parameters
b if true, enables this menu item; if false, disables it.
See Also

public synchronized void setLabel (String label)

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

Parameters
label the new label, or null for no label.
See Also

public void setShortcut (MenuShortcut s)

Set the MenuShortcut object associated with this menu item. If a menu shortcut is already associated with this menu item, it is replaced.

Parameters
s the menu shortcut to associate with this menu item.
See Also

Protected Methods

protected final void disableEvents (long eventsToDisable)

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

Parameters
eventsToDisable the event mask defining the event types
See Also

protected final void enableEvents (long eventsToEnable)

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.

Parameters
eventsToEnable the event mask defining the event types
See Also

protected void processActionEvent (ActionEvent 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.

Parameters
e the action event
See Also

protected void processEvent (AWTEvent e)

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.

Parameters
e the event
See Also