Class ItemEvent

java.lang.Object

java.util.EventObject

java.awt.AWTEvent

java.awt.event.ItemEvent

All Implemented Interfaces:

Serializable

public class ItemEvent
extends AWTEvent

A semantic event which indicates that an item was selected or deselected. This high-level event is generated by an ItemSelectable object (such as a List) when an item is selected or deselected by the user. The event is passed to every ItemListener object which registered to receive such events using the component's addItemListener method.

The object that implements the ItemListener interface gets this ItemEvent when the event occurs. The listener is spared the details of processing individual mouse movements and mouse clicks, and can instead process a "meaningful" (semantic) event like "item selected" or "item deselected".

An unspecified behavior will be caused if the id parameter of any particular ItemEvent instance is not in the range from ITEM_FIRST to ITEM_LAST.

The stateChange of any ItemEvent instance takes one of the following values:

• ItemEvent.SELECTED
• ItemEvent.DESELECTED

Assigning the value different from listed above will cause an unspecified behavior.

Since:

1.1

See Also:

• ItemSelectable
• ItemListener
• Tutorial: Writing an Item Listener
• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DESELECTED	This state-change-value indicates that a selected item was deselected.
static final int	ITEM_FIRST	The first number in the range of ids used for item events.
static final int	ITEM_LAST	The last number in the range of ids used for item events.
static final int	ITEM_STATE_CHANGED	This event id indicates that an item's state changed.
static final int	SELECTED	This state-change value indicates that an item was selected.

Fields inherited from class AWTEvent

ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, HIERARCHY_BOUNDS_EVENT_MASK, HIERARCHY_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, INVOCATION_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, MOUSE_WHEEL_EVENT_MASK, PAINT_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK, WINDOW_FOCUS_EVENT_MASK, WINDOW_STATE_EVENT_MASK

Modifier and Type	Field	Description
static final long	ACTION_EVENT_MASK	The event mask for selecting action events.
static final long	ADJUSTMENT_EVENT_MASK	The event mask for selecting adjustment events.
static final long	COMPONENT_EVENT_MASK	The event mask for selecting component events.
protected boolean	consumed	Controls whether or not the event is sent back down to the peer once the source has processed it - false means it's sent to the peer; true means it's not.
static final long	CONTAINER_EVENT_MASK	The event mask for selecting container events.
static final long	FOCUS_EVENT_MASK	The event mask for selecting focus events.
static final long	HIERARCHY_BOUNDS_EVENT_MASK	The event mask for selecting hierarchy bounds events.
static final long	HIERARCHY_EVENT_MASK	The event mask for selecting hierarchy events.
protected int	id	The event's id.
static final long	INPUT_METHOD_EVENT_MASK	The event mask for selecting input method events.
static final long	INVOCATION_EVENT_MASK	The event mask for selecting invocation events.
static final long	ITEM_EVENT_MASK	The event mask for selecting item events.
static final long	KEY_EVENT_MASK	The event mask for selecting key events.
static final long	MOUSE_EVENT_MASK	The event mask for selecting mouse events.
static final long	MOUSE_MOTION_EVENT_MASK	The event mask for selecting mouse motion events.
static final long	MOUSE_WHEEL_EVENT_MASK	The event mask for selecting mouse wheel events.
static final long	PAINT_EVENT_MASK	The event mask for selecting paint events.
static final int	RESERVED_ID_MAX	The maximum value for reserved AWT event IDs.
static final long	TEXT_EVENT_MASK	The event mask for selecting text events.
static final long	WINDOW_EVENT_MASK	The event mask for selecting window events.
static final long	WINDOW_FOCUS_EVENT_MASK	The event mask for selecting window focus events.
static final long	WINDOW_STATE_EVENT_MASK	The event mask for selecting window state events.

Fields inherited from class EventObject

source

Modifier and Type	Field	Description
protected Object	source	The object on which the Event initially occurred.

Constructor Summary

Constructors

Constructor	Description
ItemEvent(ItemSelectable source, int id, Object item, int stateChange)	Constructs an ItemEvent object.

Method Summary

Modifier and Type	Method	Description
Object	getItem()	Returns the item affected by the event.
ItemSelectable	getItemSelectable()	Returns the originator of the event.
int	getStateChange()	Returns the type of state change (selected or deselected).
String	paramString()	Returns a parameter string identifying this item event.

Methods inherited from class AWTEvent

consume, getID, isConsumed, setSource, toString

Modifier and Type	Method	Description
protected void	consume()	Consumes this event, if this event can be consumed.
int	getID()	Returns the event type.
protected boolean	isConsumed()	Returns whether this event has been consumed.
void	setSource(Object newSource)	Retargets an event to a new source.
String	toString()	Returns a String representation of this object.

Methods inherited from class EventObject

getSource

Modifier and Type	Method	Description
Object	getSource()	The object on which the Event initially occurred.

Methods inherited from class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Field Details

ITEM_FIRST

public static final int ITEM_FIRST

The first number in the range of ids used for item events.

See Also:

• Constant Field Values

ITEM_LAST

public static final int ITEM_LAST

The last number in the range of ids used for item events.

See Also:

• Constant Field Values

ITEM_STATE_CHANGED

public static final int ITEM_STATE_CHANGED

This event id indicates that an item's state changed.

See Also:

• Constant Field Values

SELECTED

public static final int SELECTED

This state-change value indicates that an item was selected.

See Also:

• Constant Field Values

DESELECTED

public static final int DESELECTED

This state-change-value indicates that a selected item was deselected.

See Also:

• Constant Field Values

Constructor Details

ItemEvent

public ItemEvent(ItemSelectable source,
 int id,
 Object item,
 int stateChange)

Constructs an ItemEvent object.

This method throws an IllegalArgumentException if source is null.

Parameters:

source - The ItemSelectable object that originated the event

id - The integer that identifies the event type. For information on allowable values, see the class description for ItemEvent

item - An object -- the item affected by the event

stateChange - An integer that indicates whether the item was selected or deselected. For information on allowable values, see the class description for ItemEvent

Throws:

IllegalArgumentException - if source is null

See Also:

• getItemSelectable()
• AWTEvent.getID()
• getStateChange()

Method Details

getItemSelectable

public ItemSelectable getItemSelectable()

Returns the originator of the event.

Returns:

the ItemSelectable object that originated the event.

getItem

public Object getItem()

Returns the item affected by the event.

Returns:

the item (object) that was affected by the event

getStateChange

public int getStateChange()

Returns the type of state change (selected or deselected).

Returns:

an integer that indicates whether the item was selected or deselected

See Also:

• SELECTED
• DESELECTED

paramString

public String paramString()

Returns a parameter string identifying this item event. This method is useful for event-logging and for debugging.

Overrides:

paramString in class AWTEvent

Returns:

a string identifying the event and its attributes