Package org.eclipse.swt.widgets

Class Item

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.swt.widgets.Item

Direct Known Subclasses:

CoolItem, CTabItem, ExpandItem, MenuItem, TabItem, TableColumn, TableItem, TaskItem, ToolItem, TrayItem, TreeColumn, TreeItem

public abstract class Item
extends Widget

This class is the abstract superclass of all non-windowed user interface objects that occur within specific controls. For example, a tree will contain tree items.

Styles:

(none)

Events:

(none)

See Also:

• Sample code and further information

Constructor Summary

Constructors

Constructor	Description
Item(Widget parent, int style)	Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.
Item(Widget parent, int style, int index)	Constructs a new instance of this class given its parent and 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

Modifier and Type	Method	Description
protected void	checkSubclass()	Checks that this class can be subclassed.
Image	getImage()	Returns the receiver's image if it has one, or null if it does not.
String	getText()	Returns the receiver's text, which will be an empty string if it has never been set.
void	setImage(Image image)	Sets the receiver's image to the argument, which may be null indicating that no image should be displayed.
void	setText(String string)	Sets the receiver's text.

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

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

Methods inherited from class java.lang.Object

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

Constructor Details

Item

public Item(Widget parent,
 int style)

Constructs a new instance of this class given its parent 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 widget which will be the parent of the new instance (cannot be null)

style - the style of item 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

See Also:

• SWT
• Widget.getStyle()

Item

public Item(Widget parent,
 int style,
 int index)

Constructs a new instance of this class given its parent and 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 widget which will be the parent of the new instance (cannot be null)

style - the style of item to construct

index - the zero-relative index at which 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

See Also:

• SWT
• Widget.getStyle()

Method Details

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 Widget

getImage

public Image getImage()

Returns the receiver's image if it has one, or null if it does not.

Returns:

the receiver's image

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

getText

public String getText()

Returns the receiver's text, which will be an empty string if it has never been set.

Returns:

the receiver's text

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

setImage

public void setImage(Image image)

Sets the receiver's image to the argument, which may be null indicating that no image should be displayed.

Parameters:

image - the image to display on the receiver (may be null)

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if the image has been disposed

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.

Note: If control characters like '\n', '\t' etc. are used in the string, then the behavior is platform dependent.

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