public Class Button

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

widgetSelected is called when the control is selected by the user. 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:SelectionListener

the listener which should be notified

Exceptions

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, SelectionEvent

Returns a value which describes the position of the text or image in the receiver. The value will be one of LEFT, RIGHT or CENTER unless the receiver is an ARROW button, in which case, the alignment will indicate the direction of the arrow (one of LEFT, RIGHT, UP or DOWN).

Returns:int

the alignment

Exceptions

SWTException:

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

Returns true if the receiver is grayed, and false otherwise. When the widget does not have the CHECK style, return false.

Returns:boolean

the grayed state of the checkbox

Exceptions

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

3.4

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

Returns:Image

the receiver's image

Exceptions

SWTException:

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

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. When it is of type TOGGLE, it is selected when it is pushed in. If the receiver is of any other type, this method returns false.

Returns:boolean

the selection state

Exceptions

SWTException:

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

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

Returns:String

the receiver's text

Exceptions

SWTException:

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

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

Parameters

listener:SelectionListener

the listener which should no longer be notified

Exceptions

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

Controls how text, images and arrows will be displayed in the receiver. The argument should be one of LEFT, RIGHT or CENTER unless the receiver is an ARROW button, in which case, the argument indicates the direction of the arrow (one of LEFT, RIGHT, UP or DOWN).

Parameters

alignment:int

the new alignment

Exceptions

SWTException:

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

Overrides org.eclipse.swt.widgets.Control.setEnabled.

Enables the receiver if the argument is true, and disables it otherwise.

A disabled control is typically not selectable from the user interface and draws with an inactive or "grayed" look.

Parameters

enabled:boolean

the new enabled state

Annotations

@Override

Exceptions

SWTException:

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

Sets the grayed state of the receiver. This state change only applies if the control was created with the SWT.CHECK style.

Parameters

grayed:boolean

the new grayed state

Exceptions

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

3.4

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

Note that a Button can display an image and text simultaneously.

Parameters

image:Image

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

Exceptions

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

Sets the selection state of the receiver, if it is of type CHECK, RADIO, or TOGGLE.

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

Parameters

selected:boolean

the new selection state

Exceptions

SWTException:

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

Sets the receiver's text.

This method sets the button label. The label may include the mnemonic character but must not contain line delimiters.

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 emphasized in a platform specific manner. The mnemonic indicator character '&' can be escaped by doubling it in the string, causing a single '&' to be displayed.

Note that a Button can display an image and text simultaneously on Windows (starting with XP), GTK+ and OSX. On other platforms, a Button that has an image and text set into it will display the image or text that was set most recently.

Also note, if control characters like '\n', '\t' etc. are used in the string, then the behavior is platform dependent.

Parameters

string:String

the new text

Exceptions

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