Package org.eclipse.rap.rwt.widgets

Class DropDown

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.rap.rwt.widgets.DropDown

All Implemented Interfaces:

Adaptable

public class DropDown
extends Widget

Instances of this class represent a list of items that are attached to a control (parent). If made visible (setVisibility(true)), the list appears attached to the control. The user can select an item from the list using the arrows keys and Enter, or the mouse. The list disappears automatically if the control looses focus, if an item is clicked, or if the escape key is pressed. This class supports the RWT.MARKUP_ENABLED property the same way Table and Tree do.

Events:

DefaultSelection, Selection

IMPORTANT: This class is not intended to be subclassed.

Since:

2.3

Constructor Summary

Constructors

Constructor	Description
DropDown(Control parent)	Constructs a new instance of this class given its parent.
DropDown(Control parent, int style)	Constructs a new instance of this class given its parent and a style value describing its behavior.

Method Summary

Modifier and Type	Method	Description
void	addListener(int eventType, Listener listener)	Adds the listener to the collection of listeners who will be notified when an event of the given type occurs.
void	dispose()	Disposes of the operating system resources associated with the receiver and all its descendents.
<T> T	getAdapter(Class<T> adapter)	Implementation of the Adaptable interface.
String[]	getItems()	Returns a (possibly empty) array of Strings which are the items in the receiver.
Control	getParent()	Returns the receiver's parent, which must be a Control.
int	getSelectionIndex()	Returns the zero-relative index of the item which is currently selected in the receiver, or -1 if no item is selected.
boolean	getVisible()	Returns true if the receiver is visible, and false otherwise.
int	getVisibleItemCount()	Gets the number of items that are visible in the receiver's list.
void	removeListener(int eventType, Listener listener)	Removes the listener from the collection of listeners who will be notified when an event of the given type occurs.
void	setData(String key, Object value)	Sets the application defined property of the receiver with the specified name to the given value.
void	setItems(String[] items)	Sets the receiver's items to be the given array of items.
void	setSelectionIndex(int selection)	Selects the item at the given zero-relative index in the receiver.
void	setVisible(boolean visible)	Marks the receiver as visible if the argument is true, and marks it invisible otherwise.
void	setVisibleItemCount(int itemCount)	Sets the maximum number of items that are visible in the receiver's list.

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

addDisposeListener, checkSubclass, checkWidget, getData, getData, getDisplay, getListeners, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, reskin, setData, toString

Methods inherited from class java.lang.Object

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

Constructor Details

DropDown

public DropDown(Control parent,
 int style)

Constructs a new instance of this class given its parent and a style value describing its behavior.

Parameters:

parent - a control, usually Text, which will be the parent of the new instance (cannot be null)

style - the style of widget 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

Since:

3.2

See Also:

• Text
• Widget.checkSubclass()

DropDown

public DropDown(Control parent)

Constructs a new instance of this class given its parent.

Parameters:

parent - a control, usually Text, which will be the parent of the new instance (cannot be null)

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:

• Text
• Widget.checkSubclass()

Method Details

setItems

public void setItems(String[] items)

Sets the receiver's items to be the given array of items.

Parameters:

items - the array of items

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

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the items array is null
• ERROR_INVALID_ARGUMENT - if an item in the items array is null

getItems

public String[] getItems()

Returns a (possibly empty) array of Strings which are the items in the receiver.

Note: This is not the actual structure used by the receiver to maintain its list of items, so modifying the array will not affect the receiver.

Returns:

the items in the receiver's list

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

setSelectionIndex

public void setSelectionIndex(int selection)

Selects the item at the given zero-relative index in the receiver. If the item at the index was already selected, it remains selected. Indices that are out of range are ignored.

Parameters:

selection - the index of the item to select

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

getSelectionIndex

public int getSelectionIndex()

Returns the zero-relative index of the item which is currently selected in the receiver, or -1 if no item is selected.

Returns:

the index of the selected item or -1

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

setVisibleItemCount

public void setVisibleItemCount(int itemCount)

Sets the maximum number of items that are visible in the receiver's list.

Parameters:

itemCount - the new number of items to be visible (default is 5)

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

getVisibleItemCount

public int getVisibleItemCount()

Gets the number of items that are visible in the receiver's list.

Returns:

the number of items that are visible

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

setVisible

public void setVisible(boolean visible)

Marks the receiver as visible if the argument is true, and marks it invisible otherwise.

Parameters:

visible - the new visibility 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

getVisible

public boolean getVisible()

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

The initial value is false.

Returns:

the receiver's visibility 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

getParent

public Control getParent()

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

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

dispose

public void dispose()

Description copied from class: Widget

Disposes of the operating system resources associated with the receiver and all its descendents. After this method has been invoked, the receiver and all descendents will answer true when sent the message isDisposed(). Any internal connections between the widgets in the tree will have been removed to facilitate garbage collection.

NOTE: This method is not called recursively on the descendents of the receiver. This means that, widget implementers can not detect when a widget is being disposed of by re-implementing this method, but should instead listen for the Dispose event.

Overrides:

dispose in class Widget

See Also:

• Widget.addDisposeListener(org.eclipse.swt.events.DisposeListener)
• Widget.removeDisposeListener(org.eclipse.swt.events.DisposeListener)
• Widget.checkWidget()

setData

public void setData(String key,
 Object value)

Description copied from class: Widget

Sets the application defined property of the receiver with the specified name to the given value.

Applications may associate arbitrary objects with the receiver in this fashion. If the objects stored in the properties need to be notified when the widget is disposed of, it is the application's responsibility to hook the Dispose event on the widget and do so.

Overrides:

setData in class Widget

Parameters:

key - the name of the property

value - the new value for the property

See Also:

• Widget.getData(String)

addListener

public void addListener(int eventType,
 Listener listener)

Description copied from class: Widget

Adds the listener to the collection of listeners who will be notified when an event of the given type occurs. When the event does occur in the widget, the listener is notified by sending it the handleEvent() message. The event type is one of the event constants defined in class SWT.

Overrides:

addListener in class Widget

Parameters:

eventType - the type of event to listen for

listener - the listener which should be notified when the event occurs

See Also:

• Listener
• SWT
• Widget.removeListener(int, org.eclipse.swt.widgets.Listener)
• Widget.notifyListeners(int, org.eclipse.swt.widgets.Event)

removeListener

public void removeListener(int eventType,
 Listener listener)

Description copied from class: Widget

Removes the listener from the collection of listeners who will be notified when an event of the given type occurs. The event type is one of the event constants defined in class SWT.

Overrides:

removeListener in class Widget

Parameters:

eventType - the type of event to listen for

listener - the listener which should no longer be notified when the event occurs

See Also:

• Listener
• SWT
• Widget.addListener(int, org.eclipse.swt.widgets.Listener)
• Widget.notifyListeners(int, org.eclipse.swt.widgets.Event)

getAdapter

public <T> T getAdapter(Class<T> adapter)

Description copied from class: Widget

Implementation of the Adaptable interface.

IMPORTANT: This method is not part of the RWT public API. It is marked public only so that it can be shared within the packages provided by RWT. It should never be accessed from application code.

Specified by:

getAdapter in interface Adaptable

Overrides:

getAdapter in class Widget

Parameters:

adapter - the lookup class

Returns:

an object that can be cast to the given class or null if there is no adapter associated with the given class.