java.lang.Object java.awt.MenuComponent java.awt.MenuItem
public class MenuItem
All items in a menu must belong to the class 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.
Nested Class Summary | |
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protected class |
MenuItem.AccessibleAWTMenuItem
Inner class of MenuItem used to provide default support for accessibility. |
Nested classes/interfaces inherited from class java.awt. MenuComponent |
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MenuComponent.AccessibleAWTMenuComponent |
Constructor Summary | |
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MenuItem
() Constructs a new MenuItem with an empty label and no keyboard shortcut. |
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MenuItem
(
String
label) Constructs a new MenuItem with the specified label and no keyboard shortcut. |
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MenuItem
(
String
label,
MenuShortcut
s) Create a menu item with an associated keyboard shortcut. |
Method Summary | ||
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void |
addActionListener
(
ActionListener
l) Adds the specified action listener to receive action events from this menu item. |
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void |
addNotify
() Creates the menu item's peer. |
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void |
deleteShortcut
() Delete any MenuShortcut object associated with this menu item. |
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void |
disable
() Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean). |
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protected void |
disableEvents
(long eventsToDisable) Disables event delivery to this menu item for events defined by the specified event mask parameter. |
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void |
enable
() Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean). |
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void |
enable
(boolean b) Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean). |
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protected void |
enableEvents
(long eventsToEnable) Enables event delivery to this menu item for events to be defined by the specified event mask parameter |
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AccessibleContext |
getAccessibleContext
() Gets the AccessibleContext associated with this MenuItem. |
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String |
getActionCommand
() Gets the command name of the action event that is fired by this menu item. |
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ActionListener [] |
getActionListeners
() Returns an array of all the action listeners registered on this menu item. |
|
String |
getLabel
() Gets the label for this menu item. |
|
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getListeners
(
Class
<T> listenerType) Returns an array of all the objects currently registered as FooListeners upon this MenuItem. |
|
MenuShortcut |
getShortcut
() Get the MenuShortcut object associated with this menu item, |
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boolean |
isEnabled
() Checks whether this menu item is enabled. |
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String |
paramString
() Returns a string representing the state of this MenuItem. |
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protected void |
processActionEvent
(
ActionEvent
e) Processes action events occurring on this menu item, by dispatching them to any registered ActionListener objects. |
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protected void |
processEvent
(
AWTEvent
e) Processes events on this menu item. |
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void |
removeActionListener
(
ActionListener
l) Removes the specified action listener so it no longer receives action events from this menu item. |
|
void |
setActionCommand
(
String
command) Sets the command name of the action event that is fired by this menu item. |
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void |
setEnabled
(boolean b) Sets whether or not this menu item can be chosen. |
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void |
setLabel
(
String
label) Sets the label for this menu item to the specified label. |
|
void |
setShortcut
(
MenuShortcut
s) Set the MenuShortcut object associated with this menu item. |
Methods inherited from class java.awt. MenuComponent |
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dispatchEvent , getFont , getName , getParent , getPeer , getTreeLock , postEvent , removeNotify , setFont , setName , toString |
Methods inherited from class java.lang. Object |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Constructor Detail |
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public MenuItem() throws HeadlessException
public MenuItem(String label) throws HeadlessException
public MenuItem(String label, MenuShortcut s) throws HeadlessException
Method Detail |
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public void addNotify()
public String getLabel()
public void setLabel(String label)
public boolean isEnabled()
public void setEnabled(boolean b)
@Deprecated public void enable()
@Deprecated public void enable(boolean b)
@Deprecated public void disable()
public MenuShortcut getShortcut()
public void setShortcut(MenuShortcut s)
public void deleteShortcut()
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.
protected final void disableEvents(long eventsToDisable)
public void setActionCommand(String command)
By default, the action command is set to the label of the menu item.
public String getActionCommand()
public void addActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
public void removeActionListener(ActionListener l)
Refer to AWT Threading Issues for details on AWT's threading model.
public ActionListener[] getActionListeners()
public <T extends EventListener> T[] getListeners(Class<T> listenerType)
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.
protected void processEvent(AWTEvent e)
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.
protected void processActionEvent(ActionEvent e)
Note that if the event parameter is null the behavior is unspecified and may result in an exception.
public String paramString()
public AccessibleContext getAccessibleContext()