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ItemEvent (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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java.awt.event
Class ItemEvent

java.lang.Object
  java.util.EventObject
      java.awt.AWTEvent
          java.awt.event.ItemEvent

All Implemented Interfaces:

Serializable

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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".

Since:

1.1

See Also:

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

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Field Summary
static int	DESELECTED           This state-change-value indicates that a selected item was deselected.
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, 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 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, getID, isConsumed, setSource, toString

 

Methods inherited from class java.util.EventObject
getSource

 

Methods inherited from class java.lang.Object
clone, equals, finalize, 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.

See Also:

Constant Field Values

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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

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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

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SELECTED

public static final int SELECTED

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

See Also:

Constant Field Values

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DESELECTED

public static final int DESELECTED

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

See Also:

Constant Field Values

Constructor Detail

ItemEvent

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

Constructs an ItemEvent object.

Note that passing in an invalid id results in unspecified behavior. This method throws an IllegalArgumentException if source is null.

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

Throws:

IllegalArgumentException - if source is null

Method Detail

getItemSelectable

public ItemSelectable getItemSelectable()

Returns the originator of the event.

Returns:

the ItemSelectable object that originated the event.

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getItem

public Object getItem()

Returns the item affected by the event.

Returns:

the item (object) that was affected by the event

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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

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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

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