ItemSelectable
, Serializable
, Accessible
public class CheckboxMenuItem extends MenuItem implements ItemSelectable, Accessible
The following picture depicts a menu which contains an instance of CheckBoxMenuItem
:
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.
Modifier and Type | Class | Description |
---|---|---|
protected class |
CheckboxMenuItem.AccessibleAWTCheckboxMenuItem |
Inner class of CheckboxMenuItem used to provide default support for accessibility. |
MenuItem.AccessibleAWTMenuItem
MenuComponent.AccessibleAWTMenuComponent
Constructor | Description |
---|---|
CheckboxMenuItem() |
Create a check box menu item with an empty label. |
CheckboxMenuItem |
Create a check box menu item with the specified label. |
CheckboxMenuItem |
Create a check box menu item with the specified label and state. |
Modifier and Type | Method | Description |
---|---|---|
void |
addItemListener |
Adds the specified item listener to receive item events from this check box menu item. |
void |
addNotify() |
Creates the peer of the checkbox item. |
AccessibleContext |
getAccessibleContext() |
Gets the AccessibleContext associated with this CheckboxMenuItem. |
ItemListener[] |
getItemListeners() |
Returns an array of all the item listeners registered on this checkbox menuitem. |
<T extends EventListener> |
getListeners |
Returns an array of all the objects currently registered as FooListener s upon this CheckboxMenuItem . |
Object[] |
getSelectedObjects() |
Returns the array (length 1) containing the checkbox menu item label or null if the checkbox is not selected. |
boolean |
getState() |
Determines whether the state of this check box menu item is "on" or "off." |
String |
paramString() |
Returns a string representing the state of this CheckBoxMenuItem . |
protected void |
processEvent |
Processes events on this check box menu item. |
protected void |
processItemEvent |
Processes item events occurring on this check box menu item by dispatching them to any registered ItemListener objects. |
void |
removeItemListener |
Removes the specified item listener so that it no longer receives item events from this check box menu item. |
void |
setState |
Sets this check box menu item to the specified state. |
addActionListener, deleteShortcut, disable, disableEvents, enable, enable, enableEvents, getActionCommand, getActionListeners, getLabel, getShortcut, isEnabled, processActionEvent, removeActionListener, setActionCommand, setEnabled, setLabel, setShortcut
dispatchEvent, getFont, getName, getParent, getTreeLock, postEvent, removeNotify, setFont, setName, toString
public CheckboxMenuItem() throws HeadlessException
HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic CheckboxMenuItem(String label) throws HeadlessException
label
- a string label for the check box menu item, or null
for an unlabeled menu item.HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic CheckboxMenuItem(String label, boolean state) throws HeadlessException
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."HeadlessException
- if GraphicsEnvironment.isHeadless() returns truepublic void addNotify()
public boolean getState()
true
indicates "on" and false
indicates "off"public void setState(boolean b)
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.
b
- true
if the check box menu item is on, otherwise false
public Object[] getSelectedObjects()
getSelectedObjects
in interface ItemSelectable
null
public void addItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
addItemListener
in interface ItemSelectable
l
- the item listenerpublic void removeItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
removeItemListener
in interface ItemSelectable
l
- the item listenerpublic ItemListener[] getItemListeners()
ItemListener
s or an empty array if no item listeners are currently registeredpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListener
s upon this CheckboxMenuItem
. FooListener
s 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.
getListeners
in class MenuItem
T
- the type of the listenerslistenerType
- the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener
FooListener
s on this checkbox menuitem, or an empty array if no such listeners have been addedClassCastException
- if listenerType
doesn't specify a class or interface that implements java.util.EventListener
protected void processEvent(AWTEvent e)
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.
processEvent
in class MenuItem
e
- the eventprotected void processItemEvent(ItemEvent e)
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:
ItemListener
object is registered via addItemListener
. enableEvents
. Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
e
- the item eventpublic String paramString()
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
.paramString
in class MenuItem
public AccessibleContext getAccessibleContext()
getAccessibleContext
in interface Accessible
getAccessibleContext
in class MenuItem
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.desktop/java/awt/CheckboxMenuItem.html