Serializable
, Accessible
CheckboxMenuItem
, Menu
public class MenuItem extends MenuComponent implements Accessible
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 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.
Modifier and Type | Class | Description |
---|---|---|
protected class |
MenuItem.AccessibleAWTMenuItem |
Inner class of MenuItem used to provide default support for accessibility. |
MenuComponent.AccessibleAWTMenuComponent
Constructor | Description |
---|---|
MenuItem() |
Constructs a new MenuItem with an empty label and no keyboard shortcut. |
MenuItem |
Constructs a new MenuItem with the specified label and no keyboard shortcut. |
MenuItem |
Create a menu item with an associated keyboard shortcut. |
Modifier and Type | Method | Description |
---|---|---|
void |
addActionListener |
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. |
void |
disable() |
Deprecated. |
protected final void |
disableEvents |
Disables event delivery to this menu item for events defined by the specified event mask parameter. |
void |
enable() |
Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean) . |
void |
enable |
Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean) . |
protected final void |
enableEvents |
Enables event delivery to this menu item for events to be defined by the specified event mask parameter |
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. |
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> |
getListeners |
Returns an array of all the objects currently registered as FooListener s 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 . |
protected void |
processActionEvent |
Processes action events occurring on this menu item, by dispatching them to any registered ActionListener objects. |
protected void |
processEvent |
Processes events on this menu item. |
void |
removeActionListener |
Removes the specified action listener so it no longer receives action events from this menu item. |
void |
setActionCommand |
Sets the command name of the action event that is fired by this menu item. |
void |
setEnabled |
Sets whether or not this menu item can be chosen. |
void |
setLabel |
Sets the label for this menu item to the specified label. |
void |
setShortcut |
Set the MenuShortcut object associated with this menu item. |
dispatchEvent, getFont, getName, getParent, getTreeLock, postEvent, removeNotify, setFont, setName, toString
public MenuItem() throws HeadlessException
HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.public MenuItem(String label) throws HeadlessException
label
- the label for this menu item.HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.public MenuItem(String label, MenuShortcut s) throws HeadlessException
label
- the label for this menu item.s
- the instance of MenuShortcut
associated with this menu item.HeadlessException
- if GraphicsEnvironment.isHeadless() returns true.public void addNotify()
public String getLabel()
null
if this menu item has no label.public void setLabel(String label)
label
- the new label, or null
for no label.public boolean isEnabled()
true
if the item is enabled; otherwise false
public void setEnabled(boolean b)
b
- if true
, enables this menu item; if false
, disables it.@Deprecated public void enable()
setEnabled(boolean)
.@Deprecated public void enable(boolean b)
setEnabled(boolean)
.b
- if true
, enables this menu item; otherwise disables@Deprecated public void disable()
setEnabled(boolean)
.public MenuShortcut getShortcut()
MenuShortcut
object associated with this menu item,null
if none has been specified.public void setShortcut(MenuShortcut s)
MenuShortcut
object associated with this menu item. If a menu shortcut is already associated with this menu item, it is replaced.s
- the menu shortcut to associate with this menu item.public void deleteShortcut()
MenuShortcut
object associated with this menu item.protected final void enableEvents(long eventsToEnable)
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.
eventsToEnable
- the event mask defining the event typesprotected final void disableEvents(long eventsToDisable)
eventsToDisable
- the event mask defining the event typespublic void setActionCommand(String command)
By default, the action command is set to the label of the menu item.
command
- the action command to be set for this menu item.public String getActionCommand()
public void addActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the action listener.public void removeActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
l
- the action listener.public ActionListener[] getActionListeners()
ActionListener
s or an empty array if no action listeners are currently registeredpublic <T extends EventListener> T[] getListeners(Class<T> listenerType)
FooListener
s upon this MenuItem
. 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 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.
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 menu item, 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)
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.
processEvent
in class MenuComponent
e
- the eventprotected void processActionEvent(ActionEvent e)
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: ActionListener
object is registered via addActionListener
. enableEvents
. Note that if the event parameter is null
the behavior is unspecified and may result in an exception.
e
- the action eventpublic String paramString()
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
.paramString
in class MenuComponent
public AccessibleContext getAccessibleContext()
getAccessibleContext
in interface Accessible
getAccessibleContext
in class MenuComponent
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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/MenuItem.html
setEnabled(boolean)
.