org.eclipse.swt.widgets

Class MenuItem

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.swt.widgets.Item

org.eclipse.swt.widgets.MenuItem

public class MenuItem
extends Item

Instances of this class represent a selectable user interface object that issues notification when pressed and released.

Styles:

CHECK, CASCADE, PUSH, RADIO, SEPARATOR

Events:

Arm, Help, Selection

Note: Only one of the styles CHECK, CASCADE, PUSH, RADIO and SEPARATOR may be specified.

IMPORTANT: This class is not intended to be subclassed.

See Also:

Sample code and further information

Restriction:

This class is not intended to be subclassed by clients.

Constructor Summary

Constructors

Constructor and Description
MenuItem(Menu parent, int style) Constructs a new instance of this class given its parent (which must be a Menu) and a style value describing its behavior and appearance.
MenuItem(Menu parent, int style, int index) Constructs a new instance of this class given its parent (which must be a Menu), a style value describing its behavior and appearance, and the index at which to place it in the items maintained by its parent.

Method Summary

Methods

Modifier and Type	Method and Description
void	addArmListener(ArmListener listener) Adds the listener to the collection of listeners who will be notified when the arm events are generated for the control, by sending it one of the messages defined in the ArmListener interface.
void	addHelpListener(HelpListener listener) Adds the listener to the collection of listeners who will be notified when the help events are generated for the control, by sending it one of the messages defined in the HelpListener interface.
void	addSelectionListener(SelectionListener listener) Adds the listener to the collection of listeners who will be notified when the menu item is selected by the user, by sending it one of the messages defined in the SelectionListener interface.
protected void	checkSubclass() Checks that this class can be subclassed.
int	getAccelerator() Returns the widget accelerator.
boolean	getEnabled() Returns true if the receiver is enabled, and false otherwise.
int	getID() Gets the identifier associated with the receiver.
Menu	getMenu() Returns the receiver's cascade menu if it has one or null if it does not.
Menu	getParent() Returns the receiver's parent, which must be a Menu.
boolean	getSelection() Returns true if the receiver is selected, and false otherwise.
boolean	isEnabled() Returns true if the receiver is enabled and all of the receiver's ancestors are enabled, and false otherwise.
void	removeArmListener(ArmListener listener) Removes the listener from the collection of listeners who will be notified when the arm events are generated for the control.
void	removeHelpListener(HelpListener listener) Removes the listener from the collection of listeners who will be notified when the help events are generated for the control.
void	removeSelectionListener(SelectionListener listener) Removes the listener from the collection of listeners who will be notified when the control is selected by the user.
void	setAccelerator(int accelerator) Sets the widget accelerator.
void	setEnabled(boolean enabled) Enables the receiver if the argument is true, and disables it otherwise.
void	setID(int id) Sets the identifier associated with the receiver to the argument.
void	setImage(Image image) Sets the image the receiver will display to the argument.
void	setMenu(Menu menu) Sets the receiver's pull down menu to the argument.
void	setSelection(boolean selected) Sets the selection state of the receiver.
void	setText(String string) Sets the receiver's text.

Methods inherited from class org.eclipse.swt.widgets.Item

getImage, getText

Methods inherited from class org.eclipse.swt.widgets.Widget

addDisposeListener, addListener, checkWidget, dispose, getData, getData, getDisplay, getListeners, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, reskin, setData, setData, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

MenuItem

public MenuItem(Menu parent,
        int style)

Constructs a new instance of this class given its parent (which must be a Menu) and a style value describing its behavior and appearance. The item is added to the end of the items maintained by its parent.

The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

Parameters:

parent - a menu control which will be the parent of the new instance (cannot be null)

style - the style of control to construct

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
• ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass

See Also:

SWT.CHECK, SWT.CASCADE, SWT.PUSH, SWT.RADIO, SWT.SEPARATOR, Widget.checkSubclass(), Widget.getStyle()

MenuItem

public MenuItem(Menu parent,
        int style,
        int index)

Constructs a new instance of this class given its parent (which must be a Menu), a style value describing its behavior and appearance, and the index at which to place it in the items maintained by its parent.

The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

Parameters:

parent - a menu control which will be the parent of the new instance (cannot be null)

style - the style of control to construct

index - the zero-relative index to store the receiver in its parent

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null
• ERROR_INVALID_RANGE - if the index is not between 0 and the number of elements in the parent (inclusive)

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
• ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass

See Also:

SWT.CHECK, SWT.CASCADE, SWT.PUSH, SWT.RADIO, SWT.SEPARATOR, Widget.checkSubclass(), Widget.getStyle()

Method Detail

addArmListener

public void addArmListener(ArmListener listener)

Adds the listener to the collection of listeners who will be notified when the arm events are generated for the control, by sending it one of the messages defined in the ArmListener interface.

Parameters:

listener - the listener which should be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

ArmListener, removeArmListener(org.eclipse.swt.events.ArmListener)

addHelpListener

public void addHelpListener(HelpListener listener)

Adds the listener to the collection of listeners who will be notified when the help events are generated for the control, by sending it one of the messages defined in the HelpListener interface.

Parameters:

listener - the listener which should be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

HelpListener, removeHelpListener(org.eclipse.swt.events.HelpListener)

addSelectionListener

public void addSelectionListener(SelectionListener listener)

Adds the listener to the collection of listeners who will be notified when the menu item is selected by the user, by sending it one of the messages defined in the SelectionListener interface.

When widgetSelected is called, the stateMask field of the event object is valid. widgetDefaultSelected is not called.

When the SWT.RADIO style bit is set, the widgetSelected method is also called when the receiver loses selection because another item in the same radio group was selected by the user. During widgetSelected the application can use getSelection() to determine the current selected state of the receiver.

Parameters:

listener - the listener which should be notified when the menu item is selected by the user

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

SelectionListener, removeSelectionListener(org.eclipse.swt.events.SelectionListener), SelectionEvent

checkSubclass

protected void checkSubclass()

Description copied from class: Widget

Checks that this class can be subclassed.

The SWT class library is intended to be subclassed only at specific, controlled points (most notably, Composite and Canvas when implementing new widgets). This method enforces this rule unless it is overridden.

IMPORTANT: By providing an implementation of this method that allows a subclass of a class which does not normally allow subclassing to be created, the implementer agrees to be fully responsible for the fact that any such subclass will likely fail between SWT releases and will be strongly platform specific. No support is provided for user-written classes which are implemented in this fashion.

The ability to subclass outside of the allowed SWT classes is intended purely to enable those not on the SWT development team to implement patches in order to get around specific limitations in advance of when those limitations can be addressed by the team. Subclassing should not be attempted without an intimate and detailed understanding of the hierarchy.

Overrides:

checkSubclass in class Item

getAccelerator

public int getAccelerator()

Returns the widget accelerator. An accelerator is the bit-wise OR of zero or more modifier masks and a key. Examples: SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2. The default value is zero, indicating that the menu item does not have an accelerator.

Returns:

the accelerator or 0

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getEnabled

public boolean getEnabled()

Returns true if the receiver is enabled, and false otherwise. A disabled menu item is typically not selectable from the user interface and draws with an inactive or "grayed" look.

Returns:

the receiver's enabled state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

isEnabled()

getID

public int getID()

Gets the identifier associated with the receiver.

Returns:

the receiver's identifier

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.7

getMenu

public Menu getMenu()

Returns the receiver's cascade menu if it has one or null if it does not. Only CASCADE menu items can have a pull down menu. The sequence of key strokes, button presses and/or button releases that are used to request a pull down menu is platform specific.

Returns:

the receiver's menu

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getParent

public Menu getParent()

Returns the receiver's parent, which must be a Menu.

Returns:

the receiver's parent

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getSelection

public boolean getSelection()

Returns true if the receiver is selected, and false otherwise.

When the receiver is of type CHECK or RADIO, it is selected when it is checked.

Returns:

the selection state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

isEnabled

public boolean isEnabled()

Returns true if the receiver is enabled and all of the receiver's ancestors are enabled, and false otherwise. A disabled menu item is typically not selectable from the user interface and draws with an inactive or "grayed" look.

Returns:

the receiver's enabled state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

getEnabled()

removeArmListener

public void removeArmListener(ArmListener listener)

Removes the listener from the collection of listeners who will be notified when the arm events are generated for the control.

Parameters:

listener - the listener which should no longer be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

ArmListener, addArmListener(org.eclipse.swt.events.ArmListener)

removeHelpListener

public void removeHelpListener(HelpListener listener)

Removes the listener from the collection of listeners who will be notified when the help events are generated for the control.

Parameters:

listener - the listener which should no longer be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

HelpListener, addHelpListener(org.eclipse.swt.events.HelpListener)

removeSelectionListener

public void removeSelectionListener(SelectionListener listener)

Removes the listener from the collection of listeners who will be notified when the control is selected by the user.

Parameters:

listener - the listener which should no longer be notified

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the listener is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

SelectionListener, addSelectionListener(org.eclipse.swt.events.SelectionListener)

setAccelerator

public void setAccelerator(int accelerator)

Sets the widget accelerator. An accelerator is the bit-wise OR of zero or more modifier masks and a key. Examples: SWT.MOD1 | SWT.MOD2 | 'T', SWT.MOD3 | SWT.F2. SWT.CONTROL | SWT.SHIFT | 'T', SWT.ALT | SWT.F2. The default value is zero, indicating that the menu item does not have an accelerator.

Parameters:

accelerator - an integer that is the bit-wise OR of masks and a key

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setEnabled

public void setEnabled(boolean enabled)

Enables the receiver if the argument is true, and disables it otherwise. A disabled menu item is typically not selectable from the user interface and draws with an inactive or "grayed" look.

Parameters:

enabled - the new enabled state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setID

public void setID(int id)

Sets the identifier associated with the receiver to the argument.

Parameters:

id - the new identifier. This must be a non-negative value. System-defined identifiers are negative values.

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
• ERROR_INVALID_ARGUMENT - if called with an negative-valued argument.

Since:

3.7

setImage

public void setImage(Image image)

Sets the image the receiver will display to the argument.

Note: This operation is a hint and is not supported on platforms that do not have this concept (for example, Windows NT). Furthermore, some platforms (such as GTK), cannot display both a check box and an image at the same time. Instead, they hide the image and display the check box.

Overrides:

setImage in class Item

Parameters:

image - the image to display

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setMenu

public void setMenu(Menu menu)

Sets the receiver's pull down menu to the argument. Only CASCADE menu items can have a pull down menu. The sequence of key strokes, button presses and/or button releases that are used to request a pull down menu is platform specific.

Note: Disposing of a menu item that has a pull down menu will dispose of the menu. To avoid this behavior, set the menu to null before the menu item is disposed.

Parameters:

menu - the new pull down menu

Throws:

IllegalArgumentException -

• ERROR_MENU_NOT_DROP_DOWN - if the menu is not a drop down menu
• ERROR_MENUITEM_NOT_CASCADE - if the menu item is not a CASCADE
• ERROR_INVALID_ARGUMENT - if the menu has been disposed
• ERROR_INVALID_PARENT - if the menu is not in the same widget tree

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setSelection

public void setSelection(boolean selected)

Sets the selection state of the receiver.

When the receiver is of type CHECK or RADIO, it is selected when it is checked.

Parameters:

selected - the new selection state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setText

public void setText(String string)

Sets the receiver's text. The string may include the mnemonic character and accelerator text.

Mnemonics are indicated by an '&' that causes the next character to be the mnemonic. When the user presses a key sequence that matches the mnemonic, a selection event occurs. On most platforms, the mnemonic appears underlined but may be emphasised in a platform specific manner. The mnemonic indicator character '&' can be escaped by doubling it in the string, causing a single '&' to be displayed.

Accelerator text is indicated by the '\t' character. On platforms that support accelerator text, the text that follows the '\t' character is displayed to the user, typically indicating the key stroke that will cause the item to become selected. On most platforms, the accelerator text appears right aligned in the menu. Setting the accelerator text does not install the accelerator key sequence. The accelerator key sequence is installed using #setAccelerator.

Overrides:

setText in class Item

Parameters:

string - the new text

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the text is null

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

setAccelerator(int)