Java(TM) 2 Platform, Standard Edition, v1.2.2 API Specification: Class ItemEvent - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

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Java^TM 2 Platform
Standard Edition

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java.awt.event
Class ItemEvent

java.lang.Object
  |
  +--java.util.EventObject
        |
        +--java.awt.AWTEvent
              |
              +--java.awt.event.ItemEvent

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 de-selected. 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".

See Also:: ItemSelectable, ItemListener, Tutorial: Writing an Item Listener, Reference: The Java Class Libraries (update file), Serialized Form

Field Summary

static int DESELECTED
          This state-change-value indicates that a selected item was un-selected.

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

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

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

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

Fields inherited from class java.awt.AWTEvent

ACTION_EVENT_MASK, ADJUSTMENT_EVENT_MASK, COMPONENT_EVENT_MASK, consumed, CONTAINER_EVENT_MASK, FOCUS_EVENT_MASK, id, INPUT_METHOD_EVENT_MASK, ITEM_EVENT_MASK, KEY_EVENT_MASK, MOUSE_EVENT_MASK, MOUSE_MOTION_EVENT_MASK, RESERVED_ID_MAX, TEXT_EVENT_MASK, WINDOW_EVENT_MASK

Fields inherited from class java.util.EventObject

source

Constructor Summary

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

Method Summary

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 java.awt.AWTEvent

consume, finalize, getID, isConsumed, toString

Methods inherited from class java.util.EventObject

getSource

Methods inherited from class java.lang.Object

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

Field Detail

ITEM_FIRST

public static final int ITEM_FIRST

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

ITEM_LAST

public static final int ITEM_LAST

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

ITEM_STATE_CHANGED

public static final int ITEM_STATE_CHANGED

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

SELECTED

public static final int SELECTED

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

DESELECTED

public static final int DESELECTED

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

Constructor Detail

ItemEvent

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

Constructs an ItemEvent object.

Parameters:: source - the ItemSelectable object that originated the event; id - an integer that identifies the event type; item - an object -- the item affected by the event; stateChange - an integer that indicates whether the item was selected or deselected

Method Detail

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