Java java.awt Class MenuItem（JDK8）

Constructor Detail

• MenuItem

  public MenuItem()
           throws HeadlessException

  Constructs a new MenuItem with an empty label and no keyboard shortcut.

  Throws:

  HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

  Since:

  JDK1.1

  See Also:

  GraphicsEnvironment.isHeadless()

• MenuItem

  public MenuItem(String label)
           throws HeadlessException

  Constructs a new MenuItem with the specified label and no keyboard shortcut. Note that use of "-" in a label is reserved to indicate a separator between menu items. By default, all menu items except for separators are enabled.

  Parameters:

  label - the label for this menu item.

  Throws:

  HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

  Since:

  JDK1.0

  See Also:

  GraphicsEnvironment.isHeadless()

• MenuItem

  public MenuItem(String label,
                  MenuShortcut s)
           throws HeadlessException

  Create a menu item with an associated keyboard shortcut. Note that use of "-" in a label is reserved to indicate a separator between menu items. By default, all menu items except for separators are enabled.

  Parameters:

  label - the label for this menu item.

  s - the instance of MenuShortcut associated with this menu item.

  Throws:

  HeadlessException - if GraphicsEnvironment.isHeadless() returns true.

  Since:

  JDK1.1

  See Also:

  GraphicsEnvironment.isHeadless()

Method Detail

• addNotify

  public void addNotify()

  Creates the menu item's peer. The peer allows us to modify the appearance of the menu item without changing its functionality.

• getLabel

  public String getLabel()

  Gets the label for this menu item.

  Returns:

  the label of this menu item, or null if this menu item has no label.

  Since:

  JDK1.0

  See Also:

  setLabel(java.lang.String)

• setLabel

  public void setLabel(String label)

  Sets the label for this menu item to the specified label.

  Parameters:

  label - the new label, or null for no label.

  Since:

  JDK1.0

  See Also:

  getLabel()

• isEnabled

  public boolean isEnabled()

  Checks whether this menu item is enabled.

  Since:

  JDK1.0

  See Also:

  setEnabled(boolean)

• setEnabled

  public void setEnabled(boolean b)

  Sets whether or not this menu item can be chosen.

  Parameters:

  b - if true, enables this menu item; if false, disables it.

  Since:

  JDK1.1

  See Also:

  isEnabled()

• enable

  @Deprecated
  public void enable()

  Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).

• enable

  @Deprecated
  public void enable(boolean b)

  Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).

• disable

  @Deprecated
  public void disable()

  Deprecated. As of JDK version 1.1, replaced by setEnabled(boolean).

• getShortcut

  public MenuShortcut getShortcut()

  Get the MenuShortcut object associated with this menu item,

  Returns:

  the menu shortcut associated with this menu item, or null if none has been specified.

  Since:

  JDK1.1

  See Also:

  setShortcut(java.awt.MenuShortcut)

• setShortcut

  public void setShortcut(MenuShortcut s)

  Set the MenuShortcut object associated with this menu item. If a menu shortcut is already associated with this menu item, it is replaced.

  Parameters:

  s - the menu shortcut to associate with this menu item.

  Since:

  JDK1.1

  See Also:

  getShortcut()

• deleteShortcut

  public void deleteShortcut()

  Delete any MenuShortcut object associated with this menu item.

  Since:

  JDK1.1

• enableEvents

  protected final void enableEvents(long eventsToEnable)

  Enables event delivery to this menu item for events to be defined by the specified event mask parameter

  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.

  Parameters:

  eventsToEnable - the event mask defining the event types

  Since:

  JDK1.1

  See Also:

  processEvent(java.awt.AWTEvent), disableEvents(long), Component.enableEvents(long)

• disableEvents

  protected final void disableEvents(long eventsToDisable)

  Disables event delivery to this menu item for events defined by the specified event mask parameter.

  Parameters:

  eventsToDisable - the event mask defining the event types

  Since:

  JDK1.1

  See Also:

  processEvent(java.awt.AWTEvent), enableEvents(long), Component.disableEvents(long)

• setActionCommand

  public void setActionCommand(String command)

  Sets the command name of the action event that is fired by this menu item.

  By default, the action command is set to the label of the menu item.

  Parameters:

  command - the action command to be set for this menu item.

  Since:

  JDK1.1

  See Also:

  getActionCommand()

• getActionCommand

  public String getActionCommand()

  Gets the command name of the action event that is fired by this menu item.

  Since:

  JDK1.1

  See Also:

  setActionCommand(java.lang.String)

• addActionListener

  public void addActionListener(ActionListener l)

  Adds the specified action listener to receive action events from this menu item. If l is null, no exception is thrown and no action is performed.

  Refer to AWT Threading Issues for details on AWT's threading model.

  Parameters:

  l - the action listener.

  Since:

  JDK1.1

  See Also:

  removeActionListener(java.awt.event.ActionListener), getActionListeners(), ActionEvent, ActionListener

• removeActionListener

  public void removeActionListener(ActionListener l)

  Removes the specified action listener so it no longer receives action events from this menu item. If l is null, no exception is thrown and no action is performed.

  Refer to AWT Threading Issues for details on AWT's threading model.

  Parameters:

  l - the action listener.

  Since:

  JDK1.1

  See Also:

  addActionListener(java.awt.event.ActionListener), getActionListeners(), ActionEvent, ActionListener

• getActionListeners

  public ActionListener[] getActionListeners()

  Returns an array of all the action listeners registered on this menu item.

  Returns:

  all of this menu item's ActionListeners or an empty array if no action listeners are currently registered

  Since:

  1.4

  See Also:

  addActionListener(java.awt.event.ActionListener), removeActionListener(java.awt.event.ActionListener), ActionEvent, ActionListener

• getListeners

  public <T extends EventListener> T[] getListeners(Class<T> listenerType)

  Returns an array of all the objects currently registered as FooListeners upon this MenuItem. 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 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.

  Parameters:

  listenerType - the type of listeners requested; this parameter should specify an interface that descends from java.util.EventListener

  Returns:

  an array of all objects registered as FooListeners on this menu item, or an empty array if no such listeners have been added

  Throws:

  ClassCastException - if listenerType doesn't specify a class or interface that implements java.util.EventListener

  Since:

  1.3

  See Also:

  getActionListeners()

• processEvent

  protected void processEvent(AWTEvent e)

  Processes events on this menu item. If the event is an instance of 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.

  Overrides:

  processEvent in class MenuComponent

  Parameters:

  e - the event

  Since:

  JDK1.1

  See Also:

  processActionEvent(java.awt.event.ActionEvent)

• processActionEvent

  protected void processActionEvent(ActionEvent e)

  Processes action events occurring on this menu item, by dispatching them to any registered 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:

  • An ActionListener object is registered via addActionListener.
  • Action events are enabled via enableEvents.

  Note that if the event parameter is null the behavior is unspecified and may result in an exception.

  Parameters:

  e - the action event

  Since:

  JDK1.1

  See Also:

  ActionEvent, ActionListener, enableEvents(long)

• paramString

  public String paramString()

  Returns a string representing the state of this 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.

  Overrides:

  paramString in class MenuComponent

  Returns:

  the parameter string of this menu item

• getAccessibleContext

  public AccessibleContext getAccessibleContext()

  Gets the AccessibleContext associated with this MenuItem. For menu items, the AccessibleContext takes the form of an AccessibleAWTMenuItem. A new AccessibleAWTMenuItem instance is created if necessary.

  Specified by:

  getAccessibleContext in interface Accessible

  Overrides:

  getAccessibleContext in class MenuComponent

  Returns:

  an AccessibleAWTMenuItem that serves as the AccessibleContext of this MenuItem

  Since:

  1.3