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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
:
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. |
|
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. |
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 FooListener s
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 |
getState() 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 |
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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 |
---|
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 trueMethod Detail |
---|
public synchronized void addItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the item listenerpublic void addNotify()
addNotify
in class MenuItem
public AccessibleContext getAccessibleContext()
getAccessibleContext
in class MenuItem
public synchronized ItemListener[] getItemListeners()
ItemListener
s
or an empty array if no item
listeners are currently registeredpublic EventListener[] getListeners(Class 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
listenerType
- 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 addedpublic synchronized Object[] getSelectedObjects()
public boolean getState()
true
indicates "on" and
false
indicates "off"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 MenuItem
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 synchronized void removeItemListener(ItemListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the item listenerpublic synchronized 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
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