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.
ItemEvent,
ItemListener,
Serialized Form| Modifier and Type | Class and Description |
|---|---|
protected class |
CheckboxMenuItem.AccessibleAWTCheckboxMenuItem
Inner class of CheckboxMenuItem used to provide default support for
accessibility.
|
MenuItem.AccessibleAWTMenuItemMenuComponent.AccessibleAWTMenuComponent| Constructor and Description |
|---|
CheckboxMenuItem()
Create a check box menu item with an empty label.
|
CheckboxMenuItem(String 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.
|
| Modifier and Type | Method and Description |
|---|---|
void |
addItemListener(ItemListener l)
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(Class<T> listenerType)
Returns an array of all the objects currently registered
as
FooListeners
upon this CheckboxMenuItem. |
Object[] |
getSelectedObjects()
Returns the an 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(AWTEvent e)
Processes events on this check box menu item.
|
protected void |
processItemEvent(ItemEvent e)
Processes item events occurring on this check box menu item by
dispatching them to any registered
ItemListener objects. |
void |
removeItemListener(ItemListener l)
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 specified state.
|
addActionListener, deleteShortcut, disable, disableEvents, enable, enable, enableEvents, getActionCommand, getActionListeners, getLabel, getShortcut, isEnabled, processActionEvent, removeActionListener, setActionCommand, setEnabled, setLabel, setShortcutdispatchEvent, getFont, getName, getParent, getPeer, getTreeLock, postEvent, removeNotify, setFont, setName, toStringpublic CheckboxMenuItem()
throws HeadlessException
HeadlessException - if GraphicsEnvironment.isHeadless()
returns trueGraphicsEnvironment.isHeadless()public 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 trueGraphicsEnvironment.isHeadless()public 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 trueGraphicsEnvironment.isHeadless()public void addNotify()
addNotify in class MenuItemToolkit.createCheckboxMenuItem(java.awt.CheckboxMenuItem),
Component.getToolkit()public boolean getState()
true indicates "on" and
false indicates "off"setState(boolean)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 falsegetState()public Object[] getSelectedObjects()
getSelectedObjects in interface ItemSelectableItemSelectablepublic void addItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
addItemListener in interface ItemSelectablel - the item listenerremoveItemListener(java.awt.event.ItemListener),
getItemListeners(),
setState(boolean),
ItemEvent,
ItemListenerpublic void removeItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
removeItemListener in interface ItemSelectablel - the item listeneraddItemListener(java.awt.event.ItemListener),
getItemListeners(),
ItemEvent,
ItemListenerpublic ItemListener[] getItemListeners()
ItemListeners
or an empty array if no item
listeners are currently registeredaddItemListener(java.awt.event.ItemListener),
removeItemListener(java.awt.event.ItemListener),
ItemEvent,
ItemListenerpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
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.
getListeners in class MenuItemlistenerType - the type of listeners requested; this parameter
should specify an interface that descends from
java.util.EventListenerFooListeners 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.EventListenergetItemListeners()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 MenuIteme - the eventItemEvent,
processItemEvent(java.awt.event.ItemEvent)protected 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 eventItemEvent,
ItemListener,
addItemListener(java.awt.event.ItemListener),
MenuItem.enableEvents(long)public 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 MenuItempublic AccessibleContext getAccessibleContext()
getAccessibleContext in interface AccessiblegetAccessibleContext in class MenuItem Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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