This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.


java.awt
class CheckboxMenuItem

java.lang.Object extended by java.awt.MenuComponent extended by java.awt.MenuItem extended by java.awt.CheckboxMenuItem
All Implemented Interfaces:
ItemSelectable, Serializable, Accessible

Most common way to construct:

CheckboxMenuItem cmi = new CheckboxMenuItem("Directed");

Based on 10 examples


public class CheckboxMenuItem
extends MenuItem
implements ItemSelectable, Accessible

This class represents a check box that can be included in a menu. Selecting the check box in the menu changes its state from "on" to "off" or from "off" to "on."

The following picture depicts a menu which contains an instance of CheckBoxMenuItem:

Menu labeled Examples, containing items Basic, Simple, Check, and More Examples. The Check item is a CheckBoxMenuItem instance, in the off state.

The item labeled Check shows a check box menu item in its "off" state.

When a check box menu item is selected, AWT sends an item event to the item. Since the event is an instance of ItemEvent, the processEvent method examines the event and passes it along to processItemEvent. The latter method redirects the event to any ItemListener objects that have registered an interest in item events generated by this menu item.


Nested Class Summary
protected class

           Inner class of CheckboxMenuItem used to provide default support for accessibility.
Nested classes/interfaces inherited from class java.awt.MenuItem
MenuItem.AccessibleAWTMenuItem
 
Nested classes/interfaces inherited from class java.awt.MenuComponent
MenuComponent.AccessibleAWTMenuComponent
   
Constructor Summary

          Create a check box menu item with an empty label.

          Create a check box menu item with the specified label.
CheckboxMenuItem(String label, boolean state)

          Create a check box menu item with the specified label and state.
 
Method Summary
 void

          Adds the specified item listener to receive item events from this check box menu item.
 void

          Creates the peer of the checkbox item.
 AccessibleContext

          Gets the AccessibleContext associated with this CheckboxMenuItem.
 ItemListener[]

          Returns an array of all the item listeners registered on this checkbox menuitem.
 EventListener[]
getListeners(Class listenerType)

          Returns an array of all the objects currently registered as FooListeners upon this CheckboxMenuItem.
 Object[]

          Returns the an array (length 1) containing the checkbox menu item label or null if the checkbox is not selected.
 boolean

          Determines whether the state of this check box menu item is "on" or "off."
 String

          Returns a string representing the state of this CheckBoxMenuItem.
protected void

          Processes events on this check box menu item.
protected void

          Processes item events occurring on this check box menu item by dispatching them to any registered ItemListener objects.
 void

          Removes the specified item listener so that it no longer receives item events from this check box menu item.
 void
setState(boolean b)

          Sets this check box menu item to the specifed state.
 
Methods inherited from class java.awt.MenuItem
addActionListener, addNotify, deleteShortcut, disable, disableEvents, enable, enable, enableEvents, getAccessibleContext, getActionCommand, getActionListeners, getLabel, getListeners, getShortcut, isEnabled, paramString, processActionEvent, processEvent, removeActionListener, setActionCommand, setEnabled, setLabel, setShortcut
 
Methods inherited from class java.awt.MenuComponent
dispatchEvent, getAccessibleContext, getFont, getName, getParent, getPeer, getTreeLock, paramString, postEvent, processEvent, removeNotify, setFont, setName, toString
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

CheckboxMenuItem

public CheckboxMenuItem()
                 throws HeadlessException
Create a check box menu item with an empty label. The item's state is initially set to "off."

Throws:
HeadlessException - if GraphicsEnvironment.isHeadless() returns true

CheckboxMenuItem

public CheckboxMenuItem(String label)
                 throws HeadlessException
Create a check box menu item with the specified label. The item's state is initially set to "off."

Parameters:
label - a string label for the check box menu item, or null for an unlabeled menu item.
Throws:
HeadlessException - if GraphicsEnvironment.isHeadless() returns true

CheckboxMenuItem

public CheckboxMenuItem(String label,
                        boolean state)
                 throws HeadlessException
Create a check box menu item with the specified label and state.

Parameters:
label - a string label for the check box menu item, or null for an unlabeled menu item.
state - the initial state of the menu item, where true indicates "on" and false indicates "off."
Throws:
HeadlessException - if GraphicsEnvironment.isHeadless() returns true
Method Detail

addItemListener

public synchronized void addItemListener(ItemListener l)
Adds the specified item listener to receive item events from this check box menu item. Item events are sent in response to user actions, but not in response to calls to setState(). 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 item listener

addNotify

public void addNotify()
Creates the peer of the checkbox item. This peer allows us to change the look of the checkbox item without changing its functionality. Most applications do not call this method directly.

Overrides:
addNotify in class MenuItem

getAccessibleContext

public AccessibleContext getAccessibleContext()
Gets the AccessibleContext associated with this CheckboxMenuItem. For checkbox menu items, the AccessibleContext takes the form of an AccessibleAWTCheckboxMenuItem. A new AccessibleAWTCheckboxMenuItem is created if necessary.

Overrides:
getAccessibleContext in class MenuItem
Returns:
an AccessibleAWTCheckboxMenuItem that serves as the AccessibleContext of this CheckboxMenuItem

getItemListeners

public synchronized ItemListener[] getItemListeners()
Returns an array of all the item listeners registered on this checkbox menuitem.

Returns:
all of this checkbox menuitem's ItemListeners or an empty array if no item listeners are currently registered

getListeners

public EventListener[] getListeners(Class listenerType)
Returns an array of all the objects currently registered as FooListeners upon this CheckboxMenuItem. 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 CheckboxMenuItem c for its item listeners with the following code:

ItemListener[] ils = (ItemListener[])(c.getListeners(ItemListener.class));
If no such listeners exist, this method returns an empty array.

Overrides:
getListeners in class MenuItem
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 checkbox menuitem, or an empty array if no such listeners have been added

getSelectedObjects

public synchronized Object[] getSelectedObjects()
Returns the an array (length 1) containing the checkbox menu item label or null if the checkbox is not selected.


getState

public boolean getState()
Determines whether the state of this check box menu item is "on" or "off."

Returns:
the state of this check box menu item, where true indicates "on" and false indicates "off"

paramString

public String paramString()
Returns a string representing the state of this CheckBoxMenuItem. 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.

Overrides:
paramString in class MenuItem
Returns:
the parameter string of this check box menu item

processEvent

protected void processEvent(AWTEvent e)
Processes events on this check box menu item. If the event is an instance of ItemEvent, this method invokes the processItemEvent method. If the event is not an item event, it invokes processEvent on the superclass.

Check box menu items currently support only item events.

Note that if the event parameter is null the behavior is unspecified and may result in an exception.

Overrides:
processEvent in class MenuItem
Parameters:
e - the event

processItemEvent

protected void processItemEvent(ItemEvent e)
Processes item events occurring on this check box menu item by dispatching them to any registered ItemListener objects.

This method is not called unless item events are enabled for this menu item. Item events are enabled when one of the following occurs:

Note that if the event parameter is null the behavior is unspecified and may result in an exception.

Parameters:
e - the item event

removeItemListener

public synchronized void removeItemListener(ItemListener l)
Removes the specified item listener so that it no longer receives item events from this check box 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 item listener

setState

public synchronized void setState(boolean b)
Sets this check box menu item to the specifed state. The boolean value true indicates "on" while false indicates "off."

Note that this method should be primarily used to initialize the state of the check box menu item. Programmatically setting the state of the check box menu item will not trigger an ItemEvent. The only way to trigger an ItemEvent is by user interaction.

Parameters:
b - true if the check box menu item is on, otherwise false


This documentation differs from the official API. Jadeite adds extra features to the API including: variable font sizes, constructions examples, placeholders for classes and methods, and auto-generated “See Also” links. Additionally it is missing some items found in standard Javadoc documentation, including: generics type information, “Deprecated” tags and comments, “See Also” links, along with other minor differences. Please send any questions or feedback to bam@cs.cmu.edu.
This page displays the Jadeite version of the documention, which is derived from the offical documentation that contains this copyright notice:
Copyright 2008 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.
The official Sun™ documentation can be found here at http://java.sun.com/javase/6/docs/api/.