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 declared in class java.awt.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

Fields declared in class java.util.EventObject

source

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 declared in class java.awt.AWTEvent

consume, getID, isConsumed, setSource, toString

Methods declared in class java.util.EventObject

getSource

Methods declared in class java.lang.Object

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

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